Simplify intrinsic dimension APIs (#4283)

examples/layers/rendering/src/sector_layout.dart

@@ -454,38 +454,42 @@ class RenderBoxToRenderSectorAdapter extends RenderBox with RenderObjectWithChil
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
     if (child == null)
-      return super.getMinIntrinsicWidth(constraints);
+      return 0.0;
-    return getIntrinsicDimensions(constraints).width;
+    return getIntrinsicDimensions(height: height).width;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
     if (child == null)
-      return super.getMaxIntrinsicWidth(constraints);
+      return 0.0;
-    return getIntrinsicDimensions(constraints).width;
+    return getIntrinsicDimensions(height: height).width;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
     if (child == null)
-      return super.getMinIntrinsicHeight(constraints);
+      return 0.0;
-    return getIntrinsicDimensions(constraints).height;
+    return getIntrinsicDimensions(width: width).height;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
     if (child == null)
-      return super.getMaxIntrinsicHeight(constraints);
+      return 0.0;
-    return getIntrinsicDimensions(constraints).height;
+    return getIntrinsicDimensions(width: width).height;
   }
 
-  Size getIntrinsicDimensions(BoxConstraints constraints) {
+  Size getIntrinsicDimensions({
+    double width: double.INFINITY,
+    double height: double.INFINITY
+  }) {
     assert(child is RenderSector);
     assert(child.parentData is SectorParentData);
-    assert(constraints.maxWidth < double.INFINITY || constraints.maxHeight < double.INFINITY);
+    assert(width != null);
-    double maxChildDeltaRadius = math.min(constraints.maxWidth, constraints.maxHeight) / 2.0 - innerRadius;
+    assert(height != null);
+    double maxChildDeltaRadius = math.min(width, height) / 2.0 - innerRadius;
     SectorDimensions childDimensions = child.getIntrinsicDimensions(new SectorConstraints(maxDeltaRadius: maxChildDeltaRadius), innerRadius);
     double dimension = (innerRadius + childDimensions.deltaRadius) * 2.0;
     return constraints.constrain(new Size(dimension, dimension));

examples/layers/rendering/src/solid_color_box.dart

@@ -14,31 +14,23 @@ class RenderSolidColorBox extends RenderDecoratedBox {
         super(decoration: new BoxDecoration(backgroundColor: backgroundColor));
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return constraints.constrainHeight(
+    return desiredSize.width == double.INFINITY ? 0.0 : desiredSize.width;
-      this.desiredSize == Size.infinite ? 0.0 : desiredSize.width
-    );
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return constraints.constrainWidth(
+    return desiredSize.width == double.INFINITY ? 0.0 : desiredSize.width;
-      this.desiredSize == Size.infinite ? 0.0 : desiredSize.width
-    );
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return constraints.constrainHeight(
+    return desiredSize.height == double.INFINITY ? 0.0 : desiredSize.height;
-      this.desiredSize == Size.infinite ? 0.0 : desiredSize.height
-    );
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return constraints.constrainHeight(
+    return desiredSize.height == double.INFINITY ? 0.0 : desiredSize.height;
-      this.desiredSize == Size.infinite ? 0.0 : desiredSize.height
-    );
   }
 
   @override

packages/flutter/lib/src/material/tabs.dart

@@ -100,47 +100,40 @@ class _RenderTabBar extends RenderBox with
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    BoxConstraints widthConstraints =
-        new BoxConstraints(maxWidth: constraints.maxWidth, maxHeight: constraints.maxHeight);
-
     double maxWidth = 0.0;
     RenderBox child = firstChild;
     while (child != null) {
-      maxWidth = math.max(maxWidth, child.getMinIntrinsicWidth(widthConstraints));
+      maxWidth = math.max(maxWidth, child.getMinIntrinsicWidth(height));
       final _TabBarParentData childParentData = child.parentData;
       child = childParentData.nextSibling;
     }
-    double width = isScrollable ? maxWidth : maxWidth * childCount;
+    return isScrollable ? maxWidth : maxWidth * childCount;
-    return constraints.constrainWidth(width);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    BoxConstraints widthConstraints =
-        new BoxConstraints(maxWidth: constraints.maxWidth, maxHeight: constraints.maxHeight);
-
     double maxWidth = 0.0;
+    double totalWidth = 0.0;
     RenderBox child = firstChild;
     while (child != null) {
-      maxWidth = math.max(maxWidth, child.getMaxIntrinsicWidth(widthConstraints));
+      double childWidth = child.getMaxIntrinsicWidth(height);
+      maxWidth = math.max(maxWidth, childWidth);
+      totalWidth += childWidth;
       final _TabBarParentData childParentData = child.parentData;
       child = childParentData.nextSibling;
     }
-    double width = isScrollable ? maxWidth : maxWidth * childCount;
+    return isScrollable ? totalWidth : maxWidth * childCount;
-    return constraints.constrainWidth(width);
   }
 
   double get _tabHeight => textAndIcons ? _kTextAndIconTabHeight : _kTabHeight;
   double get _tabBarHeight => _tabHeight + _kTabIndicatorHeight;
 
-  double _getIntrinsicHeight(BoxConstraints constraints) => constraints.constrainHeight(_tabBarHeight);
+  @override
+  double getMinIntrinsicHeight(double width) => _tabBarHeight;
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) => _getIntrinsicHeight(constraints);
+  double getMaxIntrinsicHeight(double width) => _tabBarHeight;
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) => _getIntrinsicHeight(constraints);
 
   void layoutFixedWidthTabs() {
     double tabWidth = size.width / childCount;

packages/flutter/lib/src/rendering/block.dart

@@ -10,8 +10,7 @@ import 'object.dart';
 /// Parent data for use with [RenderBlockBase].
 class BlockParentData extends ContainerBoxParentDataMixin<RenderBox> { }
 
-typedef double _ChildSizingFunction(RenderBox child, BoxConstraints constraints);
+typedef double _ChildSizingFunction(RenderBox child);
-typedef double _Constrainer(double value);
 
 /// Implements the block layout algorithm.
 ///
@@ -158,102 +157,65 @@ class RenderBlock extends RenderBox
     description.add('mainAxis: $mainAxis');
   }
 
-  double _getIntrinsicCrossAxis(BoxConstraints constraints, _ChildSizingFunction childSize, _Constrainer constrainer) {
+  double _getIntrinsicCrossAxis(_ChildSizingFunction childSize) {
     double extent = 0.0;
-    BoxConstraints innerConstraints;
-    switch (mainAxis) {
-      case Axis.horizontal:
-        innerConstraints = constraints.heightConstraints();
-        break;
-      case Axis.vertical:
-        innerConstraints = constraints.widthConstraints();
-        break;
-    }
     RenderBox child = firstChild;
     while (child != null) {
-      extent = math.max(extent, childSize(child, innerConstraints));
+      extent = math.max(extent, childSize(child));
       final BlockParentData childParentData = child.parentData;
       child = childParentData.nextSibling;
     }
-    return constrainer(extent);
+    return extent;
   }
 
-  double _getIntrinsicMainAxis(BoxConstraints constraints, _Constrainer constrainer) {
+  double _getIntrinsicMainAxis(_ChildSizingFunction childSize) {
     double extent = 0.0;
-    BoxConstraints innerConstraints = _getInnerConstraints(constraints);
     RenderBox child = firstChild;
     while (child != null) {
-      switch (mainAxis) {
+      extent += childSize(child);
-        case Axis.horizontal:
-          extent += child.getMaxIntrinsicWidth(innerConstraints);
-          break;
-        case Axis.vertical:
-          extent += child.getMinIntrinsicHeight(innerConstraints);
-          break;
-      }
       final BlockParentData childParentData = child.parentData;
       child = childParentData.nextSibling;
     }
-    return constrainer(extent);
+    return extent;
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.horizontal:
-        return _getIntrinsicMainAxis(constraints, constraints.constrainWidth);
+        return _getIntrinsicMainAxis((RenderBox child) => child.getMinIntrinsicWidth(height));
       case Axis.vertical:
-        return _getIntrinsicCrossAxis(
+        return _getIntrinsicCrossAxis((RenderBox child) => child.getMinIntrinsicWidth(height));
-          constraints,
-          (RenderBox child, BoxConstraints innerConstraints) => child.getMinIntrinsicWidth(innerConstraints),
-          constraints.constrainWidth
-        );
     }
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.horizontal:
-        return _getIntrinsicMainAxis(constraints, constraints.constrainWidth);
+        return _getIntrinsicMainAxis((RenderBox child) => child.getMaxIntrinsicWidth(height));
       case Axis.vertical:
-        return _getIntrinsicCrossAxis(
+        return _getIntrinsicCrossAxis((RenderBox child) => child.getMaxIntrinsicWidth(height));
-          constraints,
-          (RenderBox child, BoxConstraints innerConstraints) => child.getMaxIntrinsicWidth(innerConstraints),
-          constraints.constrainWidth
-        );
     }
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.horizontal:
-        return _getIntrinsicCrossAxis(
+        return _getIntrinsicMainAxis((RenderBox child) => child.getMinIntrinsicHeight(width));
-          constraints,
-          (RenderBox child, BoxConstraints innerConstraints) => child.getMinIntrinsicHeight(innerConstraints),
-          constraints.constrainHeight
-        );
       case Axis.vertical:
-        return _getIntrinsicMainAxis(constraints, constraints.constrainHeight);
+        return _getIntrinsicCrossAxis((RenderBox child) => child.getMinIntrinsicHeight(width));
     }
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.horizontal:
-        return _getIntrinsicCrossAxis(
+        return _getIntrinsicMainAxis((RenderBox child) => child.getMaxIntrinsicHeight(width));
-          constraints,
-          (RenderBox child, BoxConstraints innerConstraints) => child.getMaxIntrinsicHeight(innerConstraints),
-          constraints.constrainHeight
-        );
       case Axis.vertical:
-        return _getIntrinsicMainAxis(constraints, constraints.constrainHeight);
+        return _getIntrinsicCrossAxis((RenderBox child) => child.getMaxIntrinsicHeight(width));
     }
   }
 

packages/flutter/lib/src/rendering/box.dart

@@ -83,6 +83,15 @@ class BoxConstraints extends Constraints {
       minHeight = height != null ? height : 0.0,
       maxHeight = height != null ? height : double.INFINITY;
 
+  /// Creates box constraints that require the given width or height, except if they are infinite.
+  const BoxConstraints.tightForFinite({
+    double width: double.INFINITY,
+    double height: double.INFINITY
+  }): minWidth = width != double.INFINITY ? width : 0.0,
+      maxWidth = width != double.INFINITY ? width : double.INFINITY,
+      minHeight = height != double.INFINITY ? height : 0.0,
+      maxHeight = height != double.INFINITY ? height : double.INFINITY;
+
   /// Creates box constraints that forbid sizes larger than the given size.
   BoxConstraints.loose(Size size)
     : minWidth = 0.0,
@@ -486,44 +495,164 @@ abstract class RenderBox extends RenderObject {
       child.parentData = new BoxParentData();
   }
 
-  /// Returns the minimum width that this box could be without failing to paint
+  /// Returns the minimum width that this box could be without failing to
-  /// its contents within itself.
+  /// correctly paint its contents within itself, without clipping.
+  ///
+  /// The height argument may give a specific height to assume. The given height
+  /// can be infinite, meaning that the intrinsic width in an unconstrained
+  /// environment is being requested. The given height should never be negative
+  /// or null.
   ///
   /// Override in subclasses that implement [performLayout].
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  ///
-    assert(constraints.debugAssertIsValid());
+  /// If the layout algorithm is independent of the context (e.g. it always
-    return constraints.constrainWidth(0.0);
+  /// tries to be a particular size), or if the layout algorithm is
+  /// width-in-height-out, or if the layout algorithm uses both the incoming
+  /// width and height constraints (e.g. it always sizes itself to
+  /// [BoxConstraints.biggest]), then the `height` argument should be ignored.
+  ///
+  /// If the layout algorithm is strictly height-in-width-out, or is
+  /// height-in-width-out when the width is unconstrained, then the height
+  /// argument is the height to use.
+  ///
+  /// This function should never return a negative or infinite value.
+  ///
+  /// ## Examples
+  ///
+  /// ### Text
+  ///
+  /// Text is the canonical example of a width-in-height-out algorithm. The
+  /// `height` argument is therefore ignored.
+  ///
+  /// Consider the string "Hello World" The _maximum_ intrinsic width (as
+  /// returned from [getMaxIntrinsicWidth]) would be the width of the string
+  /// with no line breaks.
+  ///
+  /// The minimum intrinsic width would be the width of the widest word, "Hello"
+  /// or "World". If the text is rendered in an even narrower width, however, it
+  /// might still not overflow. For example, maybe the rendering would put a
+  /// line-break half-way through the words, as in "Hel⁞lo⁞Wor⁞ld". However,
+  /// this wouldn't be a _correct_ rendering, and [getMinIntrinsicWidth] is
+  /// supposed to render the minimum width that the box could be without failing
+  /// to _correctly_ paint the contents within itself.
+  ///
+  /// The minimum intrinsic _height_ for a given width smaller than the minimum
+  /// intrinsic width could therefore be greater than the minimum intrinsic
+  /// height for the minimum intrinsic width.
+  ///
+  /// ### Viewports (e.g. scrolling lists)
+  ///
+  /// Some render boxes are intended to clip their children. For example, the
+  /// render box for a scrolling list might always size itself to its parents'
+  /// size (or rather, to the maximum incoming constraints), regardless of the
+  /// children's sizes, and then clip the children and position them based on
+  /// the current scroll offset.
+  ///
+  /// The intrinsic dimensions in these cases still depend on the children, even
+  /// though the layout algorithm sizes the box in a way independent of the
+  /// children. It is the size that is needed to paint the box's contents (in
+  /// this case, the children) _without clipping_ that matters.
+  ///
+  /// In many cases, viewports do not have efficient access to all the children,
+  /// and therefore cannot actually return a valid answer. In this case, when
+  /// [RenderObject.debugCheckingIntrinsics] is false and asserts are enabled,
+  /// the intrinsic functions should throw; in other cases, they should return
+  /// 0.0. See [RenderVirtualViewport.debugThrowIfNotCheckingIntrinsics].
+  ///
+  /// ### Aspect-ratio-driven boxes
+  ///
+  /// Some boxes always return a fixed size based on the constraints. For these
+  /// boxes, the intrinsic functions should return the appropriate size when the
+  /// incoming `height` or `width` argument is finite, treating that as a tight
+  /// constraint in the respective direction and treating the other direction's
+  /// constraints as unbounded. This is because the definitions of
+  /// [getMinIntrinsicWidth] and [getMinIntrinsicHeight] are in terms of what
+  /// the dimensions _could be_, and such boxes can only be one size in such
+  /// cases.
+  ///
+  /// When the incoming argument is not finite, then they should return the
+  /// actual intrinsic dimensions based on the contents, as any other box would.
+  double getMinIntrinsicWidth(double height) {
+    return 0.0;
   }
 
   /// Returns the smallest width beyond which increasing the width never
-  /// decreases the preferred height.
+  /// decreases the preferred height. The preferred height is the value that
+  /// would be returned by [getMinIntrinsicHeight] for that width.
   ///
   /// Override in subclasses that implement [performLayout].
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  ///
-    assert(constraints.debugAssertIsValid());
+  /// If the layout algorithm is strictly height-in-width-out, or is
-    return constraints.constrainWidth(0.0);
+  /// height-in-width-out when the width is unconstrained, then this should
+  /// return the same value as [getMinIntrinsicWidth] for the same height.
+  ///
+  /// Otherwise, the height argument should be ignored, and the returned value
+  /// should be equal to or bigger than the value returned by
+  /// [getMinIntrinsicWidth].
+  ///
+  /// The value returned by this method might not match the size that the object
+  /// would actually take. For example, a [RenderBox] subclass that always
+  /// exactly sizes itself using [BoxConstraints.biggest] might well size itself
+  /// bigger than its max intrinsic size.
+  ///
+  /// This function should never return a negative or infinite value.
+  ///
+  /// See also examples in the definition of [getMinIntrinsicWidth].
+  double getMaxIntrinsicWidth(double height) {
+    return 0.0;
   }
 
-  /// Return the minimum height that this box could be without failing to paint
+  /// Returns the minimum height that this box could be without failing to
-  /// its contents within itself.
+  /// correctly paint its contents within itself, without clipping.
+  ///
+  /// The width argument may give a specific width to assume. The given width
+  /// can be infinite, meaning that the intrinsic height in an unconstrained
+  /// environment is being requested. The given width should never be negative
+  /// or null.
   ///
   /// Override in subclasses that implement [performLayout].
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  ///
-    assert(constraints.debugAssertIsValid());
+  /// If the layout algorithm is independent of the context (e.g. it always
-    return constraints.constrainHeight(0.0);
+  /// tries to be a particular size), or if the layout algorithm is
+  /// height-in-width-out, or if the layout algorithm uses both the incoming
+  /// height and width constraints (e.g. it always sizes itself to
+  /// [BoxConstraints.biggest]), then the `width` argument should be ignored.
+  ///
+  /// If the layout algorithm is strictly width-in-height-out, or is
+  /// width-in-height-out when the height is unconstrained, then the width
+  /// argument is the width to use.
+  ///
+  /// This function should never return a negative or infinite value.
+  ///
+  /// See also examples in the definition of [getMinIntrinsicWidth].
+  double getMinIntrinsicHeight(double width) {
+    return 0.0;
   }
 
   /// Returns the smallest height beyond which increasing the height never
-  /// decreases the preferred width.
+  /// decreases the preferred width. The preferred width is the value that
-  ///
+  /// would be returned by [getMinIntrinsicWidth] for that height.
-  /// If the layout algorithm used is width-in-height-out, i.e. the height
-  /// depends on the width and not vice versa, then this will return the same
-  /// as getMinIntrinsicHeight().
   ///
   /// Override in subclasses that implement [performLayout].
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  ///
-    assert(constraints.debugAssertIsValid());
+  /// If the layout algorithm is strictly width-in-height-out, or is
-    return constraints.constrainHeight(0.0);
+  /// width-in-height-out when the height is unconstrained, then this should
+  /// return the same value as [getMinIntrinsicHeight] for the same width.
+  ///
+  /// Otherwise, the width argument should be ignored, and the returned value
+  /// should be equal to or bigger than the value returned by
+  /// [getMinIntrinsicHeight].
+  ///
+  /// The value returned by this method might not match the size that the object
+  /// would actually take. For example, a [RenderBox] subclass that always
+  /// exactly sizes itself using [BoxConstraints.biggest] might well size itself
+  /// bigger than its max intrinsic size.
+  ///
+  /// This function should never return a negative or infinite value.
+  ///
+  /// See also examples in the definition of [getMinIntrinsicWidth].
+  double getMaxIntrinsicHeight(double width) {
+    return 0.0;
   }
 
   /// Whether this render object has undergone layout and has a [size].
@@ -766,40 +895,47 @@ abstract class RenderBox extends RenderObject {
         );
       }
       if (_debugNeedsIntrinsicSizeCheck || debugCheckIntrinsicSizes) {
-        // verify that the intrinsics are also within the constraints
+        // verify that the intrinsics are sane
         assert(!RenderObject.debugCheckingIntrinsics);
         RenderObject.debugCheckingIntrinsics = true;
-        double intrinsic;
         StringBuffer failures = new StringBuffer();
         int failureCount = 0;
-        intrinsic = getMinIntrinsicWidth(constraints);
+
-        if (intrinsic != constraints.constrainWidth(intrinsic)) {
+        double testIntrinsic(double function(double extent), String name, double constraint) {
-          failures.writeln(' * getMinIntrinsicWidth() -- returned: w=$intrinsic');
+          final double result = function(constraint);
+          if (result < 0) {
+            failures.writeln(' * $name($constraint) returned a negative value: $result');
+            failureCount += 1;
+          }
+          if (!result.isFinite) {
+            failures.writeln(' * $name($constraint) returned a non-finite value: $result');
+            failureCount += 1;
+          }
+          return result;
+        }
+
+        final double minIntrinsicWidth = testIntrinsic(getMinIntrinsicWidth, 'getMinIntrinsicWidth', constraints.maxWidth);
+        final double maxIntrinsicWidth = testIntrinsic(getMaxIntrinsicWidth, 'getMaxIntrinsicWidth', constraints.maxWidth);
+        if (minIntrinsicWidth > maxIntrinsicWidth) {
+          failures.writeln(' * getMinIntrinsicWidth(${constraints.maxWidth}) returned a larger value ($minIntrinsicWidth) than getMaxIntrinsicWidth(${constraints.maxWidth}) ($maxIntrinsicWidth)');
           failureCount += 1;
         }
-        intrinsic = getMaxIntrinsicWidth(constraints);
+        final double minIntrinsicHeight = testIntrinsic(getMinIntrinsicHeight, 'getMinIntrinsicHeight', constraints.maxHeight);
-        if (intrinsic != constraints.constrainWidth(intrinsic)) {
+        final double maxIntrinsicHeight = testIntrinsic(getMaxIntrinsicHeight, 'getMaxIntrinsicHeight', constraints.maxHeight);
-          failures.writeln(' * getMaxIntrinsicWidth() -- returned: w=$intrinsic');
+        if (minIntrinsicHeight > maxIntrinsicHeight) {
-          failureCount += 1;
+          failures.writeln(' * getMinIntrinsicHeight(${constraints.maxHeight}) returned a larger value ($minIntrinsicHeight) than getMaxIntrinsicHeight(${constraints.maxHeight}) ($maxIntrinsicHeight)');
-        }
-        intrinsic = getMinIntrinsicHeight(constraints);
-        if (intrinsic != constraints.constrainHeight(intrinsic)) {
-          failures.writeln(' * getMinIntrinsicHeight() -- returned: h=$intrinsic');
-          failureCount += 1;
-        }
-        intrinsic = getMaxIntrinsicHeight(constraints);
-        if (intrinsic != constraints.constrainHeight(intrinsic)) {
-          failures.writeln(' * getMaxIntrinsicHeight() -- returned: h=$intrinsic');
           failureCount += 1;
         }
+
+        // TODO(ianh): Test that values are internally consistent in more ways than the above.
+
         RenderObject.debugCheckingIntrinsics = false;
         _debugNeedsIntrinsicSizeCheck = false;
         if (failures.isNotEmpty) {
           assert(failureCount > 0);
           throw new FlutterError(
-            'The intrinsic dimension methods of the $runtimeType class returned values that violate the given constraints.\n'
+            'The intrinsic dimension methods of the $runtimeType class returned values that violate the intrinsic protocol contract.\n'
-            'The constraints were: $constraints\n'
+            'The following ${failureCount > 1 ? "failures" : "failure"} was detected:\n'
-            'The following method${failureCount > 1 ? "s" : ""} returned values outside of those constraints:\n'
             '$failures'
             'If you are not writing your own RenderBox subclass, then this is not\n'
             'your fault. Contact support: https://github.com/flutter/flutter/issues/new'

packages/flutter/lib/src/rendering/custom_layout.dart

@@ -239,24 +239,40 @@ class RenderCustomMultiChildLayoutBox extends RenderBox
     return constraints.constrain(_delegate.getSize(constraints));
   }
 
+  // TODO(ianh): It's a bit dubious to be using the getSize function from the delegate to
+  // figure out the intrinsic dimensions. We really should either not support intrinsics,
+  // or we should expose intrinsic delegate callbacks and throw if they're not implemented.
+
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return _getSize(constraints).width;
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return _getSize(constraints).width;
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return _getSize(constraints).height;
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return _getSize(constraints).height;
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override

packages/flutter/lib/src/rendering/editable_line.dart

@@ -192,27 +192,13 @@ class RenderEditableLine extends RenderBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _preferredHeight;
-    return constraints.constrainWidth(0.0);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _preferredHeight;
-    return constraints.constrainWidth(0.0);
-  }
-
-  @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.constrainHeight(_preferredHeight);
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.constrainHeight(_preferredHeight);
   }
 
   @override

packages/flutter/lib/src/rendering/error.dart

@@ -54,23 +54,13 @@ class RenderErrorBox extends RenderBox {
   ui.Paragraph _paragraph;
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return constraints.constrainWidth(0.0);
+    return _kMaxWidth;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return constraints.constrainWidth(_kMaxWidth);
+    return _kMaxHeight;
-  }
-
-  @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
-    return constraints.constrainHeight(0.0);
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    return constraints.constrainHeight(_kMaxHeight);
   }
 
   @override

packages/flutter/lib/src/rendering/flex.dart

@@ -71,7 +71,7 @@ enum CrossAxisAlignment {
   baseline,
 }
 
-typedef double _ChildSizingFunction(RenderBox child, BoxConstraints constraints);
+typedef double _ChildSizingFunction(RenderBox child, double extent);
 
 /// Implements the flex layout algorithm
 ///
@@ -156,25 +156,15 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
       child.parentData = new FlexParentData();
   }
 
-  double _getIntrinsicSize({ BoxConstraints constraints,
+  double _getIntrinsicSize({
-                             FlexDirection sizingDirection,
+    FlexDirection sizingDirection,
-                             _ChildSizingFunction childSize }) {
+    double extent, // the extent in the direction that isn't the sizing direction
-    assert(constraints.debugAssertIsValid());
+    _ChildSizingFunction childSize // a method to find the size in the sizing direction
-    // http://www.w3.org/TR/2015/WD-css-flexbox-1-20150514/#intrinsic-sizes
+  }) {
     if (_direction == sizingDirection) {
       // INTRINSIC MAIN SIZE
       // Intrinsic main size is the smallest size the flex container can take
       // while maintaining the min/max-content contributions of its flex items.
-      BoxConstraints childConstraints;
-      switch(_direction) {
-        case FlexDirection.horizontal:
-          childConstraints = new BoxConstraints(maxHeight: constraints.maxHeight);
-          break;
-        case FlexDirection.vertical:
-          childConstraints = new BoxConstraints(maxWidth: constraints.maxWidth);
-          break;
-      }
-
       double totalFlex = 0.0;
       double inflexibleSpace = 0.0;
       double maxFlexFractionSoFar = 0.0;
@@ -183,47 +173,24 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
         int flex = _getFlex(child);
         totalFlex += flex;
         if (flex > 0) {
-          double flexFraction = childSize(child, childConstraints) / _getFlex(child);
+          double flexFraction = childSize(child, extent) / _getFlex(child);
           maxFlexFractionSoFar = math.max(maxFlexFractionSoFar, flexFraction);
         } else {
-          inflexibleSpace += childSize(child, childConstraints);
+          inflexibleSpace += childSize(child, extent);
         }
         final FlexParentData childParentData = child.parentData;
         child = childParentData.nextSibling;
       }
-      double mainSize = maxFlexFractionSoFar * totalFlex + inflexibleSpace;
+      return maxFlexFractionSoFar * totalFlex + inflexibleSpace;
-
-      // Ensure that we don't violate the given constraints with our result
-      switch(_direction) {
-        case FlexDirection.horizontal:
-          return constraints.constrainWidth(mainSize);
-        case FlexDirection.vertical:
-          return constraints.constrainHeight(mainSize);
-      }
     } else {
       // INTRINSIC CROSS SIZE
-      // The spec wants us to perform layout into the given available main-axis
+      // Intrinsic cross size is the max of the intrinsic cross sizes of the
-      // space and return the cross size. That's too expensive, so instead we
+      // children, after the flexible children are fit into the available space,
-      // size inflexible children according to their max intrinsic size in the
+      // with the children sized using their max intrinsic dimensions.
-      // main direction and use those constraints to determine their max
+      // TODO(ianh): Support baseline alignment.
-      // intrinsic size in the cross direction. We don't care if the caller
-      // asked for max or min -- the answer is always computed using the
-      // max size in the main direction.
 
-      double availableMainSpace;
+      // Get inflexible space using the max intrinsic dimensions of fixed children in the main direction.
-      BoxConstraints childConstraints;
+      double availableMainSpace = extent;
-      switch(_direction) {
-        case FlexDirection.horizontal:
-          childConstraints = new BoxConstraints(maxHeight: constraints.maxHeight);
-          availableMainSpace = constraints.maxWidth;
-          break;
-        case FlexDirection.vertical:
-          childConstraints = new BoxConstraints(maxWidth: constraints.maxWidth);
-          availableMainSpace = constraints.maxHeight;
-          break;
-      }
-
-      // Get inflexible space using the max in the main direction
       int totalFlex = 0;
       double inflexibleSpace = 0.0;
       double maxCrossSize = 0.0;
@@ -236,16 +203,12 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
         if (flex == 0) {
           switch (_direction) {
               case FlexDirection.horizontal:
-                mainSize = child.getMaxIntrinsicWidth(childConstraints);
+                mainSize = child.getMaxIntrinsicWidth(double.INFINITY);
-                BoxConstraints widthConstraints =
+                crossSize = childSize(child, mainSize);
-                  new BoxConstraints(minWidth: mainSize, maxWidth: mainSize);
-                crossSize = child.getMaxIntrinsicHeight(widthConstraints);
                 break;
               case FlexDirection.vertical:
-                mainSize = child.getMaxIntrinsicHeight(childConstraints);
+                mainSize = child.getMaxIntrinsicHeight(double.INFINITY);
-                BoxConstraints heightConstraints =
+                crossSize = childSize(child, mainSize);
-                  new BoxConstraints(minWidth: mainSize, maxWidth: mainSize);
-                crossSize = child.getMaxIntrinsicWidth(heightConstraints);
                 break;
           }
           inflexibleSpace += mainSize;
@@ -255,79 +218,59 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
         child = childParentData.nextSibling;
       }
 
-      // Determine the spacePerFlex by allocating the remaining available space
+      // Determine the spacePerFlex by allocating the remaining available space.
       // When you're overconstrained spacePerFlex can be negative.
       double spacePerFlex = math.max(0.0,
           (availableMainSpace - inflexibleSpace) / totalFlex);
 
-      // Size remaining items, find the maximum cross size
+      // Size remaining (flexible) items, find the maximum cross size.
       child = firstChild;
       while (child != null) {
         int flex = _getFlex(child);
-        if (flex > 0) {
+        if (flex > 0)
-          double childMainSize = spacePerFlex * flex;
+          maxCrossSize = math.max(maxCrossSize, childSize(child, spacePerFlex * flex));
-          double crossSize;
-          switch (_direction) {
-            case FlexDirection.horizontal:
-              BoxConstraints childConstraints =
-                new BoxConstraints(minWidth: childMainSize, maxWidth: childMainSize);
-              crossSize = child.getMaxIntrinsicHeight(childConstraints);
-              break;
-            case FlexDirection.vertical:
-              BoxConstraints childConstraints =
-                new BoxConstraints(minHeight: childMainSize, maxHeight: childMainSize);
-              crossSize = child.getMaxIntrinsicWidth(childConstraints);
-              break;
-          }
-          maxCrossSize = math.max(maxCrossSize, crossSize);
-        }
         final FlexParentData childParentData = child.parentData;
         child = childParentData.nextSibling;
       }
 
-      // Ensure that we don't violate the given constraints with our result
+      return maxCrossSize;
-      switch(_direction) {
-        case FlexDirection.horizontal:
-          return constraints.constrainHeight(maxCrossSize);
-        case FlexDirection.vertical:
-          return constraints.constrainWidth(maxCrossSize);
-      }
     }
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
     return _getIntrinsicSize(
-      constraints: constraints,
       sizingDirection: FlexDirection.horizontal,
-      childSize: (RenderBox child, BoxConstraints innerConstraints) => child.getMinIntrinsicWidth(innerConstraints)
+      extent: height,
+      childSize: (RenderBox child, double extent) => child.getMinIntrinsicWidth(extent)
     );
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
     return _getIntrinsicSize(
-      constraints: constraints,
       sizingDirection: FlexDirection.horizontal,
-      childSize: (RenderBox child, BoxConstraints innerConstraints) => child.getMaxIntrinsicWidth(innerConstraints)
+      extent: height,
+      childSize: (RenderBox child, double extent) => child.getMaxIntrinsicWidth(extent)
     );
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
     return _getIntrinsicSize(
-      constraints: constraints,
       sizingDirection: FlexDirection.vertical,
-      childSize: (RenderBox child, BoxConstraints innerConstraints) => child.getMinIntrinsicHeight(innerConstraints)
+      extent: width,
+      childSize: (RenderBox child, double extent) => child.getMinIntrinsicHeight(extent)
     );
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
     return _getIntrinsicSize(
-      constraints: constraints,
       sizingDirection: FlexDirection.vertical,
-      childSize: (RenderBox child, BoxConstraints innerConstraints) => child.getMaxIntrinsicHeight(innerConstraints));
+      extent: width,
+      childSize: (RenderBox child, double extent) => child.getMaxIntrinsicHeight(extent)
+    );
   }
 
   @override
@@ -352,8 +295,6 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
 
   @override
   void performLayout() {
-    // Originally based on http://www.w3.org/TR/css-flexbox-1/ Section 9.7 Resolving Flexible Lengths
-
     // Determine used flex factor, size inflexible items, calculate free space.
     int totalFlex = 0;
     int totalChildren = 0;

packages/flutter/lib/src/rendering/flow.dart

@@ -240,24 +240,40 @@ class RenderFlow extends RenderBox
   @override
   bool get isRepaintBoundary => true;
 
+  // TODO(ianh): It's a bit dubious to be using the getSize function from the delegate to
+  // figure out the intrinsic dimensions. We really should either not support intrinsics,
+  // or we should expose intrinsic delegate callbacks and throw if they're not implemented.
+
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return _getSize(constraints).width;
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return _getSize(constraints).width;
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return _getSize(constraints).height;
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return _getSize(constraints).height;
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override

packages/flutter/lib/src/rendering/grid.dart

@@ -181,26 +181,34 @@ abstract class GridDelegate {
 
   /// Returns the minimum width that this grid could be without failing to paint
   /// its contents within itself.
-  double getMinIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  ///
-    return constraints.constrainWidth(_getGridSize(constraints, childCount).width);
+  /// For more details, see [RenderBox.getMinIntrinsicWidth].
+  double getMinIntrinsicWidth(double height, int childCount) {
+    return _getGridSize(new BoxConstraints.tightForFinite(height: height), childCount).width;
   }
 
   /// Returns the smallest width beyond which increasing the width never
   /// decreases the preferred height.
-  double getMaxIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  ///
-    return constraints.constrainWidth(_getGridSize(constraints, childCount).width);
+  /// For more details, see [RenderBox.getMaxIntrinsicWidth].
+  double getMaxIntrinsicWidth(double height, int childCount) {
+    return _getGridSize(new BoxConstraints.tightForFinite(height: height), childCount).width;
   }
 
   /// Return the minimum height that this grid could be without failing to paint
   /// its contents within itself.
-  double getMinIntrinsicHeight(BoxConstraints constraints, int childCount) {
+  ///
-    return constraints.constrainHeight(_getGridSize(constraints, childCount).height);
+  /// For more details, see [RenderBox.getMinIntrinsicHeight].
+  double getMinIntrinsicHeight(double width, int childCount) {
+    return _getGridSize(new BoxConstraints.tightForFinite(width: width), childCount).height;
   }
 
   /// Returns the smallest height beyond which increasing the height never
   /// decreases the preferred width.
-  double getMaxIntrinsicHeight(BoxConstraints constraints, int childCount) {
+  ///
-    return constraints.constrainHeight(_getGridSize(constraints, childCount).height);
+  /// For more details, see [RenderBox.getMaxIntrinsicHeight].
+  double getMaxIntrinsicHeight(double width, int childCount) {
+    return _getGridSize(new BoxConstraints.tightForFinite(width: width), childCount).height;
   }
 }
 
@@ -293,13 +301,13 @@ class FixedColumnCountGridDelegate extends GridDelegateWithInOrderChildPlacement
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  double getMinIntrinsicWidth(double height, int childCount) {
-    return constraints.constrainWidth(0.0);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  double getMaxIntrinsicWidth(double height, int childCount) {
-    return constraints.constrainWidth(0.0);
+    return 0.0;
   }
 }
 
@@ -359,13 +367,13 @@ class MaxTileWidthGridDelegate extends GridDelegateWithInOrderChildPlacement {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  double getMinIntrinsicWidth(double height, int childCount) {
-    return constraints.constrainWidth(0.0);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints, int childCount) {
+  double getMaxIntrinsicWidth(double height, int childCount) {
-    return constraints.constrainWidth(maxTileWidth * childCount);
+    return maxTileWidth * childCount;
   }
 }
 
@@ -470,27 +478,23 @@ class RenderGrid extends RenderVirtualViewport<GridParentData> {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _delegate.getMinIntrinsicWidth(height, virtualChildCount);
-    return _delegate.getMinIntrinsicWidth(constraints, virtualChildCount);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _delegate.getMaxIntrinsicWidth(height, virtualChildCount);
-    return _delegate.getMaxIntrinsicWidth(constraints, virtualChildCount);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _delegate.getMinIntrinsicHeight(width, virtualChildCount);
-    return _delegate.getMinIntrinsicHeight(constraints, virtualChildCount);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _delegate.getMaxIntrinsicHeight(width, virtualChildCount);
-    return _delegate.getMaxIntrinsicHeight(constraints, virtualChildCount);
   }
 
   @override

packages/flutter/lib/src/rendering/image.dart

@@ -205,31 +205,27 @@ class RenderImage extends RenderBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (_width == null && _height == null)
-      return constraints.constrainWidth(0.0);
+      return 0.0;
-    return _sizeForConstraints(constraints).width;
+    return _sizeForConstraints(new BoxConstraints.tightForFinite(height: height)).width;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _sizeForConstraints(new BoxConstraints.tightForFinite(height: height)).width;
-    return _sizeForConstraints(constraints).width;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (_width == null && _height == null)
-      return constraints.constrainHeight(0.0);
+      return 0.0;
-    return _sizeForConstraints(constraints).height;
+    return _sizeForConstraints(new BoxConstraints.tightForFinite(width: width)).height;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _sizeForConstraints(new BoxConstraints.tightForFinite(width: width)).height;
-    return _sizeForConstraints(constraints).height;
   }
 
   @override

packages/flutter/lib/src/rendering/list.dart

@@ -87,7 +87,7 @@ class RenderList extends RenderVirtualViewport<ListParentData> {
   double get _preferredExtent {
     if (itemExtent == null)
       return double.INFINITY;
-    int count = virtualChildCount;
+    final int count = virtualChildCount;
     if (count == null)
       return double.INFINITY;
     double extent = itemExtent * count;
@@ -96,44 +96,52 @@ class RenderList extends RenderVirtualViewport<ListParentData> {
     return extent;
   }
 
-  double _getIntrinsicWidth(BoxConstraints constraints) {
+  double _getIntrinsicWidth() {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.vertical:
-        return constraints.constrainWidth(0.0);
+        assert(debugThrowIfNotCheckingIntrinsics());
+        return 0.0;
       case Axis.horizontal:
-        return constraints.constrainWidth(_preferredExtent);
+        final double width = _preferredExtent;
+        if (width.isFinite)
+          return width;
+        assert(debugThrowIfNotCheckingIntrinsics());
+        return 0.0;
     }
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return _getIntrinsicWidth(constraints);
+    return _getIntrinsicWidth();
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return _getIntrinsicWidth(constraints);
+    return _getIntrinsicWidth();
   }
 
-  double _getIntrinsicHeight(BoxConstraints constraints) {
+  double _getIntrinsicHeight() {
-    assert(constraints.debugAssertIsValid());
     switch (mainAxis) {
       case Axis.vertical:
-        return constraints.constrainHeight(_preferredExtent);
+        final double height = _preferredExtent;
+        if (height.isFinite)
+          return height;
+        assert(debugThrowIfNotCheckingIntrinsics());
+        return 0.0;
       case Axis.horizontal:
-        return constraints.constrainHeight(0.0);
+        assert(debugThrowIfNotCheckingIntrinsics());
+        return 0.0;
     }
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return _getIntrinsicHeight(constraints);
+    return _getIntrinsicHeight();
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return _getIntrinsicHeight(constraints);
+    return _getIntrinsicHeight();
   }
 
   @override

packages/flutter/lib/src/rendering/overflow.dart

@@ -14,18 +14,6 @@ class RenderOffStage extends RenderBox with RenderObjectWithChildMixin<RenderBox
     this.child = child;
   }
 
-  @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) => constraints.minWidth;
-
-  @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) => constraints.minWidth;
-
-  @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) => constraints.minHeight;
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) => constraints.minHeight;
-
   @override
   bool get sizedByParent => true;
 

packages/flutter/lib/src/rendering/paragraph.dart

@@ -87,45 +87,43 @@ class RenderParagraph extends RenderBox {
     markNeedsPaint();
   }
 
-  void _layoutText(BoxConstraints constraints) {
+  void _layoutText({ double minWidth: 0.0, double maxWidth: double.INFINITY }) {
-    assert(constraints != null);
+    _textPainter.layout(minWidth: minWidth, maxWidth: _softWrap ? maxWidth : double.INFINITY);
-    assert(constraints.debugAssertIsValid());
-    _textPainter.layout(minWidth: constraints.minWidth, maxWidth: _softWrap ? constraints.maxWidth : double.INFINITY);
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    _layoutText(constraints);
+    _layoutText();
-    return constraints.constrainWidth(_textPainter.minIntrinsicWidth);
+    return _textPainter.minIntrinsicWidth;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    _layoutText(constraints);
+    _layoutText();
-    return constraints.constrainWidth(_textPainter.maxIntrinsicWidth);
+    return _textPainter.maxIntrinsicWidth;
   }
 
-  double _getIntrinsicHeight(BoxConstraints constraints) {
+  double _getIntrinsicHeight(double width) {
-    _layoutText(constraints);
+    _layoutText(minWidth: width, maxWidth: width);
-    return constraints.constrainHeight(_textPainter.height);
+    return _textPainter.height;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _getIntrinsicHeight(width);
-    return _getIntrinsicHeight(constraints);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _getIntrinsicHeight(width);
-    return _getIntrinsicHeight(constraints);
   }
 
   @override
   double computeDistanceToActualBaseline(TextBaseline baseline) {
     assert(!needsLayout);
-    _layoutText(constraints);
+    assert(constraints != null);
+    assert(constraints.debugAssertIsValid());
+    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
     return _textPainter.computeDistanceToActualBaseline(baseline);
   }
 
@@ -136,7 +134,7 @@ class RenderParagraph extends RenderBox {
   void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
     if (event is! PointerDownEvent)
       return;
-    _layoutText(constraints);
+    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
     Offset offset = entry.localPosition.toOffset();
     TextPosition position = _textPainter.getPositionForOffset(offset);
     TextSpan span = _textPainter.text.getSpanForPosition(position);
@@ -149,7 +147,7 @@ class RenderParagraph extends RenderBox {
 
   @override
   void performLayout() {
-    _layoutText(constraints);
+    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
     size = constraints.constrain(_textPainter.size);
 
     final bool didOverflowWidth = size.width < _textPainter.width;
@@ -200,7 +198,7 @@ class RenderParagraph extends RenderBox {
     //
     // If you remove this call, make sure that changing the textAlign still
     // works properly.
-    _layoutText(constraints);
+    _layoutText(minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
     final Canvas canvas = context.canvas;
     if (_hasVisualOverflow) {
       final Rect bounds = offset & size;

packages/flutter/lib/src/rendering/performance_overlay.dart

@@ -97,13 +97,13 @@ class RenderPerformanceOverlay extends RenderBox {
   bool get alwaysNeedsCompositing => true;
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return constraints.constrainWidth(0.0);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return constraints.constrainWidth(0.0);
+    return 0.0;
   }
 
   double get _intrinsicHeight {
@@ -119,13 +119,13 @@ class RenderPerformanceOverlay extends RenderBox {
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return constraints.constrainHeight(_intrinsicHeight);
+    return _intrinsicHeight;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return constraints.constrainHeight(_intrinsicHeight);
+    return _intrinsicHeight;
   }
 
   @override

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -42,35 +42,31 @@ class RenderProxyBox extends RenderBox with RenderObjectWithChildMixin<RenderBox
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMinIntrinsicWidth(constraints);
+      return child.getMinIntrinsicWidth(height);
-    return super.getMinIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMaxIntrinsicWidth(constraints);
+      return child.getMaxIntrinsicWidth(height);
-    return super.getMaxIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMinIntrinsicHeight(constraints);
+      return child.getMinIntrinsicHeight(width);
-    return super.getMinIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMaxIntrinsicHeight(constraints);
+      return child.getMaxIntrinsicHeight(width);
-    return super.getMaxIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
@@ -199,35 +195,35 @@ class RenderConstrainedBox extends RenderProxyBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double width = super.getMinIntrinsicWidth(height);
-    if (child != null)
+    if (_additionalConstraints.hasBoundedWidth)
-      return child.getMinIntrinsicWidth(_additionalConstraints.enforce(constraints));
+      return _additionalConstraints.constrainWidth(width);
-    return _additionalConstraints.enforce(constraints).constrainWidth(0.0);
+    return width;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double width = super.getMaxIntrinsicWidth(height);
-    if (child != null)
+    if (_additionalConstraints.hasBoundedWidth)
-      return child.getMaxIntrinsicWidth(_additionalConstraints.enforce(constraints));
+      return _additionalConstraints.constrainWidth(width);
-    return _additionalConstraints.enforce(constraints).constrainWidth(0.0);
+    return width;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double height = super.getMinIntrinsicHeight(width);
-    if (child != null)
+    if (_additionalConstraints.hasBoundedHeight)
-      return child.getMinIntrinsicHeight(_additionalConstraints.enforce(constraints));
+      return _additionalConstraints.constrainHeight(height);
-    return _additionalConstraints.enforce(constraints).constrainHeight(0.0);
+    return height;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double height = super.getMaxIntrinsicHeight(width);
-    if (child != null)
+    if (_additionalConstraints.hasBoundedHeight)
-      return child.getMaxIntrinsicHeight(_additionalConstraints.enforce(constraints));
+      return _additionalConstraints.constrainHeight(height);
-    return _additionalConstraints.enforce(constraints).constrainHeight(0.0);
+    return height;
   }
 
   @override
@@ -309,38 +305,6 @@ class RenderLimitedBox extends RenderProxyBox {
     );
   }
 
-  @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    if (child != null)
-      return child.getMinIntrinsicWidth(_limitConstraints(constraints));
-    return _limitConstraints(constraints).constrainWidth(0.0);
-  }
-
-  @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    if (child != null)
-      return child.getMaxIntrinsicWidth(_limitConstraints(constraints));
-    return _limitConstraints(constraints).constrainWidth(0.0);
-  }
-
-  @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    if (child != null)
-      return child.getMinIntrinsicHeight(_limitConstraints(constraints));
-    return _limitConstraints(constraints).constrainHeight(0.0);
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    if (child != null)
-      return child.getMaxIntrinsicHeight(_limitConstraints(constraints));
-    return _limitConstraints(constraints).constrainHeight(0.0);
-  }
-
   @override
   void performLayout() {
     if (child != null) {
@@ -417,27 +381,39 @@ class RenderAspectRatio extends RenderProxyBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    if (height.isFinite)
-    return constraints.minWidth;
+      return height * _aspectRatio;
+    if (child != null)
+      return child.getMinIntrinsicWidth(height);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    if (height.isFinite)
-    return constraints.constrainWidth(constraints.maxHeight * aspectRatio);
+      return height * _aspectRatio;
+    if (child != null)
+      return child.getMaxIntrinsicWidth(height);
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    if (width.isFinite)
-    return constraints.minHeight;
+      return width / _aspectRatio;
+    if (child != null)
+      return child.getMinIntrinsicHeight(width);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    if (width.isFinite)
-    return constraints.constrainHeight(constraints.maxWidth / aspectRatio);
+      return width / _aspectRatio;
+    if (child != null)
+      return child.getMaxIntrinsicHeight(width);
+    return 0.0;
   }
 
   Size _applyAspectRatio(BoxConstraints constraints) {
@@ -563,53 +539,50 @@ class RenderIntrinsicWidth extends RenderProxyBox {
     assert(child != null);
     if (constraints.hasTightWidth)
       return constraints;
-    double width = child.getMaxIntrinsicWidth(constraints);
+    final double width = child.getMaxIntrinsicWidth(constraints.maxHeight);
     assert(width == constraints.constrainWidth(width));
     return constraints.tighten(width: _applyStep(width, _stepWidth));
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return getMaxIntrinsicWidth(height);
-    return getMaxIntrinsicWidth(constraints);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child == null)
-      return constraints.constrainWidth(0.0);
+      return 0.0;
-    double childResult = child.getMaxIntrinsicWidth(constraints);
+    double childResult = child.getMaxIntrinsicWidth(height);
     assert(!childResult.isInfinite);
-    return constraints.constrainWidth(_applyStep(childResult, _stepWidth));
+    return _applyStep(childResult, _stepWidth);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child == null)
-      return constraints.constrainHeight(0.0);
+      return 0.0;
-    double childResult = child.getMinIntrinsicHeight(_getInnerConstraints(constraints));
+    double childResult = child.getMinIntrinsicHeight(_getInnerConstraints(new BoxConstraints.tightForFinite(width: width)).maxWidth);
-    assert(!childResult.isInfinite);
+    assert(childResult.isFinite);
-    return constraints.constrainHeight(_applyStep(childResult, _stepHeight));
+    return _applyStep(childResult, _stepHeight);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child == null)
-      return constraints.constrainHeight(0.0);
+      return 0.0;
-    double childResult = child.getMaxIntrinsicHeight(_getInnerConstraints(constraints));
+    double childResult = child.getMaxIntrinsicHeight(_getInnerConstraints(new BoxConstraints.tightForFinite(width: width)).maxWidth);
-    assert(!childResult.isInfinite);
+    assert(childResult.isFinite);
-    return constraints.constrainHeight(_applyStep(childResult, _stepHeight));
+    return _applyStep(childResult, _stepHeight);
   }
 
   @override
   void performLayout() {
     if (child != null) {
       BoxConstraints childConstraints = _getInnerConstraints(constraints);
+      assert(childConstraints.hasTightWidth);
       if (_stepHeight != null)
-        childConstraints.tighten(height: getMaxIntrinsicHeight(childConstraints));
+        childConstraints.tighten(height: getMaxIntrinsicHeight(childConstraints.maxWidth));
       child.layout(childConstraints, parentUsesSize: true);
       size = child.size;
     } else {
@@ -642,39 +615,28 @@ class RenderIntrinsicHeight extends RenderProxyBox {
     assert(child != null);
     if (constraints.hasTightHeight)
       return constraints;
-    double height = child.getMaxIntrinsicHeight(constraints);
+    final double height = child.getMaxIntrinsicHeight(constraints.maxWidth);
     assert(height == constraints.constrainHeight(height));
     return constraints.tighten(height: height);
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child == null)
-      return constraints.constrainWidth(0.0);
+      return 0.0;
-    return child.getMinIntrinsicWidth(_getInnerConstraints(constraints));
+    return child.getMinIntrinsicWidth(_getInnerConstraints(new BoxConstraints.tightForFinite(height: height)).maxHeight);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child == null)
-      return constraints.constrainWidth(0.0);
+      return 0.0;
-    return child.getMaxIntrinsicWidth(_getInnerConstraints(constraints));
+    return child.getMaxIntrinsicWidth(_getInnerConstraints(new BoxConstraints.tightForFinite(height: height)).maxHeight);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return getMaxIntrinsicHeight(width);
-    return getMaxIntrinsicHeight(constraints);
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    if (child == null)
-      return constraints.constrainHeight(0.0);
-    return child.getMaxIntrinsicHeight(constraints);
   }
 
   @override

packages/flutter/lib/src/rendering/rotated_box.dart

@@ -43,35 +43,31 @@ class RenderRotatedBox extends RenderBox with RenderObjectWithChildMixin<RenderB
   bool get _isVertical => quarterTurns % 2 == 1;
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    if (child == null)
-    if (child != null)
+      return 0.0;
-      return _isVertical ? child.getMinIntrinsicHeight(constraints.flipped) : child.getMinIntrinsicWidth(constraints);
+    return _isVertical ? child.getMinIntrinsicHeight(height) : child.getMinIntrinsicWidth(height);
-    return super.getMinIntrinsicWidth(constraints);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    if (child == null)
-    if (child != null)
+      return 0.0;
-      return _isVertical ? child.getMaxIntrinsicHeight(constraints.flipped) : child.getMaxIntrinsicWidth(constraints);
+    return _isVertical ? child.getMaxIntrinsicHeight(height) : child.getMaxIntrinsicWidth(height);
-    return super.getMaxIntrinsicWidth(constraints);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    if (child == null)
-    if (child != null)
+      return 0.0;
-      return _isVertical ? child.getMinIntrinsicWidth(constraints.flipped) : child.getMinIntrinsicHeight(constraints);
+    return _isVertical ? child.getMinIntrinsicWidth(width) : child.getMinIntrinsicHeight(width);
-    return super.getMinIntrinsicHeight(constraints);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    if (child == null)
-    if (child != null)
+      return 0.0;
-      return _isVertical ? child.getMaxIntrinsicWidth(constraints.flipped) : child.getMaxIntrinsicHeight(constraints);
+    return _isVertical ? child.getMaxIntrinsicWidth(width) : child.getMaxIntrinsicHeight(width);
-    return super.getMaxIntrinsicHeight(constraints);
   }
 
   Matrix4 _paintTransform;

packages/flutter/lib/src/rendering/shifted_box.dart

@@ -17,35 +17,31 @@ abstract class RenderShiftedBox extends RenderBox with RenderObjectWithChildMixi
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMinIntrinsicWidth(constraints);
+      return child.getMinIntrinsicWidth(height);
-    return super.getMinIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMaxIntrinsicWidth(constraints);
+      return child.getMaxIntrinsicWidth(height);
-    return super.getMaxIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMinIntrinsicHeight(constraints);
+      return child.getMinIntrinsicHeight(width);
-    return super.getMinIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return child.getMaxIntrinsicHeight(constraints);
+      return child.getMaxIntrinsicHeight(width);
-    return super.getMaxIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
@@ -115,39 +111,39 @@ class RenderPadding extends RenderShiftedBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double totalHorizontalPadding = padding.left + padding.right;
-    double totalPadding = padding.left + padding.right;
+    final double totalVerticalPadding = padding.top + padding.bottom;
-    if (child != null)
+    if (child != null) // next line relies on double.INFINITY absorption
-      return constraints.constrainWidth(child.getMinIntrinsicWidth(constraints.deflate(padding)) + totalPadding);
+      return child.getMinIntrinsicWidth(height - totalVerticalPadding) + totalHorizontalPadding;
-    return constraints.constrainWidth(totalPadding);
+    return totalHorizontalPadding;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double totalHorizontalPadding = padding.left + padding.right;
-    double totalPadding = padding.left + padding.right;
+    final double totalVerticalPadding = padding.top + padding.bottom;
-    if (child != null)
+    if (child != null) // next line relies on double.INFINITY absorption
-      return constraints.constrainWidth(child.getMaxIntrinsicWidth(constraints.deflate(padding)) + totalPadding);
+      return child.getMaxIntrinsicWidth(height - totalVerticalPadding) + totalHorizontalPadding;
-    return constraints.constrainWidth(totalPadding);
+    return totalHorizontalPadding;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double totalHorizontalPadding = padding.left + padding.right;
-    double totalPadding = padding.top + padding.bottom;
+    final double totalVerticalPadding = padding.top + padding.bottom;
-    if (child != null)
+    if (child != null) // next line relies on double.INFINITY absorption
-      return constraints.constrainHeight(child.getMinIntrinsicHeight(constraints.deflate(padding)) + totalPadding);
+      return child.getMinIntrinsicHeight(width - totalHorizontalPadding) + totalVerticalPadding;
-    return constraints.constrainHeight(totalPadding);
+    return totalVerticalPadding;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double totalHorizontalPadding = padding.left + padding.right;
-    double totalPadding = padding.top + padding.bottom;
+    final double totalVerticalPadding = padding.top + padding.bottom;
-    if (child != null)
+    if (child != null) // next line relies on double.INFINITY absorption
-      return constraints.constrainHeight(child.getMaxIntrinsicHeight(constraints.deflate(padding)) + totalPadding);
+      return child.getMaxIntrinsicHeight(width - totalHorizontalPadding) + totalVerticalPadding;
-    return constraints.constrainHeight(totalPadding);
+    return totalVerticalPadding;
   }
 
   @override
@@ -502,30 +498,6 @@ class RenderConstrainedOverflowBox extends RenderAligningShiftedBox {
     );
   }
 
-  @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.minWidth;
-  }
-
-  @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.minWidth;
-  }
-
-  @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.minHeight;
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return constraints.minHeight;
-  }
-
   @override
   bool get sizedByParent => true;
 
@@ -579,27 +551,23 @@ class RenderSizedOverflowBox extends RenderAligningShiftedBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _requestedSize.width;
-    return constraints.constrainWidth(_requestedSize.width);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _requestedSize.width;
-    return constraints.constrainWidth(_requestedSize.width);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _requestedSize.height;
-    return constraints.constrainHeight(_requestedSize.height);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _requestedSize.height;
-    return constraints.constrainHeight(_requestedSize.height);
   }
 
   @override
@@ -699,35 +667,51 @@ class RenderFractionallySizedOverflowBox extends RenderAligningShiftedBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    double result;
-    if (child != null)
+    if (child == null) {
-      return constraints.constrainWidth(child.getMinIntrinsicWidth(_getInnerConstraints(constraints)));
+      result = super.getMinIntrinsicWidth(height);
-    return constraints.constrainWidth(_getInnerConstraints(constraints).constrainWidth(0.0));
+    } else { // the following line relies on double.INFINITY absorption
+      result = child.getMinIntrinsicWidth(height * (_heightFactor ?? 1.0));
+    }
+    assert(result.isFinite);
+    return result / (_widthFactor ?? 1.0);
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    double result;
-    if (child != null)
+    if (child == null) {
-      return constraints.constrainWidth(child.getMaxIntrinsicWidth(_getInnerConstraints(constraints)));
+      result = super.getMaxIntrinsicWidth(height);
-    return constraints.constrainWidth(_getInnerConstraints(constraints).constrainWidth(0.0));
+    } else { // the following line relies on double.INFINITY absorption
+      result = child.getMaxIntrinsicWidth(height * (_heightFactor ?? 1.0));
+    }
+    assert(result.isFinite);
+    return result / (_widthFactor ?? 1.0);
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    double result;
-    if (child != null)
+    if (child == null) {
-      return constraints.constrainHeight(child.getMinIntrinsicHeight(_getInnerConstraints(constraints)));
+      result = super.getMinIntrinsicHeight(width);
-    return constraints.constrainHeight(_getInnerConstraints(constraints).constrainHeight(0.0));
+    } else { // the following line relies on double.INFINITY absorption
+      result = child.getMinIntrinsicHeight(width * (_widthFactor ?? 1.0));
+    }
+    assert(result.isFinite);
+    return result / (_heightFactor ?? 1.0);
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    double result;
-    if (child != null)
+    if (child == null) {
-      return constraints.constrainHeight(child.getMaxIntrinsicHeight(_getInnerConstraints(constraints)));
+      result = super.getMaxIntrinsicHeight(width);
-    return constraints.constrainHeight(_getInnerConstraints(constraints).constrainHeight(0.0));
+    } else { // the following line relies on double.INFINITY absorption
+      result = child.getMaxIntrinsicHeight(width * (_widthFactor ?? 1.0));
+    }
+    assert(result.isFinite);
+    return result / (_heightFactor ?? 1.0);
   }
 
   @override
@@ -797,28 +781,40 @@ class RenderCustomSingleChildLayoutBox extends RenderShiftedBox {
     return constraints.constrain(_delegate.getSize(constraints));
   }
 
+  // TODO(ianh): It's a bit dubious to be using the getSize function from the delegate to
+  // figure out the intrinsic dimensions. We really should either not support intrinsics,
+  // or we should expose intrinsic delegate callbacks and throw if they're not implemented.
+
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
-    return _getSize(constraints).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    final double width = _getSize(new BoxConstraints.tightForFinite(height: height)).width;
-    return _getSize(constraints).width;
+    if (width.isFinite)
+      return width;
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
-    return _getSize(constraints).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    final double height = _getSize(new BoxConstraints.tightForFinite(width: width)).height;
-    return _getSize(constraints).height;
+    if (height.isFinite)
+      return height;
+    return 0.0;
   }
 
   @override

packages/flutter/lib/src/rendering/stack.dart

@@ -224,78 +224,37 @@ abstract class RenderStackBase extends RenderBox
     }
   }
 
-  @override
+  double _getIntrinsicDimension(double mainChildSizeGetter(RenderBox child)) {
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+    double extent = 0.0;
-    assert(constraints.debugAssertIsValid());
-    double width = constraints.minWidth;
     RenderBox child = firstChild;
     while (child != null) {
       final StackParentData childParentData = child.parentData;
       if (!childParentData.isPositioned)
-        width = math.max(width, child.getMinIntrinsicWidth(constraints));
+        extent = math.max(extent, mainChildSizeGetter(child));
       assert(child.parentData == childParentData);
       child = childParentData.nextSibling;
     }
-    assert(width == constraints.constrainWidth(width));
+    return extent;
-    return width;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _getIntrinsicDimension((RenderBox child) => child.getMinIntrinsicWidth(height));
-    bool hasNonPositionedChildren = false;
-    double width = constraints.minWidth;
-    RenderBox child = firstChild;
-    while (child != null) {
-      final StackParentData childParentData = child.parentData;
-      if (!childParentData.isPositioned) {
-        hasNonPositionedChildren = true;
-        width = math.max(width, child.getMaxIntrinsicWidth(constraints));
-      }
-      assert(child.parentData == childParentData);
-      child = childParentData.nextSibling;
-    }
-    if (!hasNonPositionedChildren)
-      return constraints.constrainWidth();
-    assert(width == constraints.constrainWidth(width));
-    return width;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    return _getIntrinsicDimension((RenderBox child) => child.getMaxIntrinsicWidth(height));
-    double height = constraints.minHeight;
-    RenderBox child = firstChild;
-    while (child != null) {
-      final StackParentData childParentData = child.parentData;
-      if (!childParentData.isPositioned)
-        height = math.max(height, child.getMinIntrinsicHeight(constraints));
-      assert(child.parentData == childParentData);
-      child = childParentData.nextSibling;
-    }
-    assert(height == constraints.constrainHeight(height));
-    return height;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    return _getIntrinsicDimension((RenderBox child) => child.getMinIntrinsicHeight(width));
-    bool hasNonPositionedChildren = false;
+  }
-    double height = constraints.minHeight;
+
-    RenderBox child = firstChild;
+  @override
-    while (child != null) {
+  double getMaxIntrinsicHeight(double width) {
-      final StackParentData childParentData = child.parentData;
+    return _getIntrinsicDimension((RenderBox child) => child.getMaxIntrinsicHeight(width));
-      if (!childParentData.isPositioned) {
-        hasNonPositionedChildren = true;
-        height = math.max(height, child.getMaxIntrinsicHeight(constraints));
-      }
-      assert(child.parentData == childParentData);
-      child = childParentData.nextSibling;
-    }
-    if (!hasNonPositionedChildren)
-      return constraints.constrainHeight();
-    assert(height == constraints.constrainHeight(height));
-    return height;
   }
 
   @override

packages/flutter/lib/src/rendering/table.dart

@@ -82,7 +82,7 @@ class IntrinsicColumnWidth extends TableColumnWidth {
   double minIntrinsicWidth(Iterable<RenderBox> cells, double containerWidth) {
     double result = 0.0;
     for (RenderBox cell in cells)
-      result = math.max(result, cell.getMinIntrinsicWidth(const BoxConstraints()));
+      result = math.max(result, cell.getMinIntrinsicWidth(double.INFINITY));
     return result;
   }
 
@@ -90,7 +90,7 @@ class IntrinsicColumnWidth extends TableColumnWidth {
   double maxIntrinsicWidth(Iterable<RenderBox> cells, double containerWidth) {
     double result = 0.0;
     for (RenderBox cell in cells)
-      result = math.max(result, cell.getMaxIntrinsicWidth(const BoxConstraints()));
+      result = math.max(result, cell.getMaxIntrinsicWidth(double.INFINITY));
     return result;
   }
 
@@ -689,36 +689,33 @@ class RenderTable extends RenderBox {
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     assert(_children.length == rows * columns);
     double totalMinWidth = 0.0;
     for (int x = 0; x < columns; x += 1) {
       TableColumnWidth columnWidth = _columnWidths[x] ?? defaultColumnWidth;
       Iterable<RenderBox> columnCells = column(x);
-      totalMinWidth += columnWidth.minIntrinsicWidth(columnCells, constraints.maxWidth);
+      totalMinWidth += columnWidth.minIntrinsicWidth(columnCells, double.INFINITY);
     }
-    return constraints.constrainWidth(totalMinWidth);
+    return totalMinWidth;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     assert(_children.length == rows * columns);
     double totalMaxWidth = 0.0;
     for (int x = 0; x < columns; x += 1) {
       TableColumnWidth columnWidth = _columnWidths[x] ?? defaultColumnWidth;
       Iterable<RenderBox> columnCells = column(x);
-      totalMaxWidth += columnWidth.maxIntrinsicWidth(columnCells, constraints.maxWidth);
+      totalMaxWidth += columnWidth.maxIntrinsicWidth(columnCells, double.INFINITY);
     }
-    return constraints.constrainWidth(totalMaxWidth);
+    return totalMaxWidth;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
     // winner of the 2016 world's most expensive intrinsic dimension function award
     // honorable mention, most likely to improve if taught about memoization award
-    assert(constraints.debugAssertIsValid());
     assert(_children.length == rows * columns);
     final List<double> widths = _computeColumnWidths(constraints);
     double rowTop = 0.0;
@@ -728,16 +725,16 @@ class RenderTable extends RenderBox {
         final int xy = x + y * columns;
         RenderBox child = _children[xy];
         if (child != null)
-          rowHeight = math.max(rowHeight, child.getMaxIntrinsicHeight(new BoxConstraints.tightFor(width: widths[x])));
+          rowHeight = math.max(rowHeight, child.getMaxIntrinsicHeight(widths[x]));
       }
       rowTop += rowHeight;
     }
-    return constraints.constrainHeight(rowTop);
+    return rowTop;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return getMinIntrinsicHeight(constraints);
+    return getMinIntrinsicHeight(width);
   }
 
   double _baselineDistance;

packages/flutter/lib/src/rendering/viewport.dart

@@ -218,35 +218,31 @@ class RenderViewport extends RenderViewportBase with RenderObjectWithChildMixin<
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return constraints.constrainWidth(child.getMinIntrinsicWidth(_getInnerConstraints(constraints)));
+      return child.getMinIntrinsicWidth(height);
-    return super.getMinIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return constraints.constrainWidth(child.getMaxIntrinsicWidth(_getInnerConstraints(constraints)));
+      return child.getMaxIntrinsicWidth(height);
-    return super.getMaxIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return constraints.constrainHeight(child.getMinIntrinsicHeight(_getInnerConstraints(constraints)));
+      return child.getMinIntrinsicHeight(width);
-    return super.getMinIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
     if (child != null)
-      return constraints.constrainHeight(child.getMaxIntrinsicHeight(_getInnerConstraints(constraints)));
+      return child.getMaxIntrinsicHeight(width);
-    return super.getMaxIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   // We don't override computeDistanceToActualBaseline(), because we
@@ -353,6 +349,51 @@ abstract class RenderVirtualViewport<T extends ContainerBoxParentDataMixin<Rende
     markNeedsLayout();
   }
 
+  /// Throws an exception if asserts are enabled, unless the
+  /// [RenderObject.debugCheckingIntrinsics] flag is set.
+  ///
+  /// This is a convenience function for subclasses to call from their
+  /// intrinsic-sizing functions if they don't have a good way to generate the
+  /// numbers.
+  bool debugThrowIfNotCheckingIntrinsics() {
+    assert(() {
+      if (!RenderObject.debugCheckingIntrinsics) {
+        throw new FlutterError(
+          'RenderVirtualViewport does not support returning intrinsic dimensions.\n'
+          'Calculating the intrinsic dimensions would require walking the entire '
+          'child list, which cannot reliably and efficiently be done for render '
+          'objects that potentially generate their child list during layout.'
+        );
+      }
+      return true;
+    });
+    return true;
+  }
+
+  @override
+  double getMinIntrinsicWidth(double height) {
+    assert(debugThrowIfNotCheckingIntrinsics);
+    return 0.0;
+  }
+
+  @override
+  double getMaxIntrinsicWidth(double height) {
+    assert(debugThrowIfNotCheckingIntrinsics);
+    return 0.0;
+  }
+
+  @override
+  double getMinIntrinsicHeight(double width) {
+    assert(debugThrowIfNotCheckingIntrinsics);
+    return 0.0;
+  }
+
+  @override
+  double getMaxIntrinsicHeight(double width) {
+    assert(debugThrowIfNotCheckingIntrinsics);
+    return 0.0;
+  }
+
   @override
   bool hitTestChildren(HitTestResult result, { Point position }) {
     return defaultHitTestChildren(result, position: position + -_effectivePaintOffset);

packages/flutter/lib/src/widgets/layout_builder.dart

@@ -44,32 +44,42 @@ class _RenderLayoutBuilder extends RenderBox with RenderObjectWithChildMixin<Ren
     markNeedsLayout();
   }
 
-  double getIntrinsicWidth(BoxConstraints constraints) => constraints.constrainWidth();
+  bool _debugThrowIfNotCheckingIntrinsics() {
-
+    assert(() {
-  double getIntrinsicHeight(BoxConstraints constraints) => constraints.constrainHeight();
+      if (!RenderObject.debugCheckingIntrinsics) {
-
+        throw new FlutterError(
-  @override
+          'LayoutBuilder does not support returning intrinsic dimensions.\n'
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+          'Calculating the intrinsic dimensions would require running the layout callback speculatively, '
-    assert(constraints.debugAssertIsValid());
+          'which might mutate the live render object tree.'
-    return getIntrinsicWidth(constraints);
+        );
+      }
+      return true;
+    });
+    return true;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicHeight(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicHeight(constraints);
+    return 0.0;
+  }
+
+  @override
+  double getMaxIntrinsicHeight(double width) {
+    assert(_debugThrowIfNotCheckingIntrinsics());
+    return 0.0;
   }
 
   @override
@@ -85,7 +95,7 @@ class _RenderLayoutBuilder extends RenderBox with RenderObjectWithChildMixin<Ren
     if (callback != null)
       invokeLayoutCallback(callback);
     if (child != null)
-      child.layout(constraints.loosen(), parentUsesSize: false);
+      child.layout(constraints.loosen());
   }
 
   @override

packages/flutter/lib/src/widgets/lazy_block.dart

@@ -368,48 +368,28 @@ class _RenderLazyBlock extends RenderVirtualViewport<_LazyBlockParentData> {
     return true;
   }
 
-  double getIntrinsicWidth(BoxConstraints constraints) {
+  @override
-    switch (mainAxis) {
+  double getMinIntrinsicWidth(double height) {
-      case Axis.horizontal:
+    assert(_debugThrowIfNotCheckingIntrinsics());
-        return constraints.constrainWidth(0.0);
+    return 0.0;
-      case Axis.vertical:
-        assert(_debugThrowIfNotCheckingIntrinsics());
-        return constraints.constrainWidth(0.0);
-    }
   }
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicWidth(constraints);
+    return 0.0;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicWidth(constraints);
+    return 0.0;
-  }
-
-  double getIntrinsicHeight(BoxConstraints constraints) {
-    switch (mainAxis) {
-      case Axis.horizontal:
-        return constraints.constrainHeight(0.0);
-      case Axis.vertical:
-        assert(_debugThrowIfNotCheckingIntrinsics());
-        return constraints.constrainHeight(0.0);
-    }
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    assert(constraints.debugAssertIsValid());
+    assert(_debugThrowIfNotCheckingIntrinsics());
-    return getIntrinsicHeight(constraints);
+    return 0.0;
-  }
-
-  @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
-    assert(constraints.debugAssertIsValid());
-    return getIntrinsicHeight(constraints);
   }
 
   @override

packages/flutter/test/rendering/aspect_ratio_test.dart

@@ -4,21 +4,96 @@
 
 import 'package:flutter/rendering.dart';
 import 'package:test/test.dart';
+import 'rendering_tester.dart';
 
 void main() {
-  test('Intrinsic sizing', () {
+  test('Intrinsic sizing 2.0', () {
     RenderAspectRatio box = new RenderAspectRatio(aspectRatio: 2.0);
 
-    BoxConstraints constraints = new BoxConstraints.loose(new Size(200.0, 200.0));
+    expect(box.getMinIntrinsicWidth(200.0), 400.0);
-    expect(box.getMinIntrinsicWidth(constraints), equals(0.0));
+    expect(box.getMinIntrinsicWidth(400.0), 800.0);
-    expect(box.getMaxIntrinsicWidth(constraints), equals(200.0));
-    expect(box.getMinIntrinsicHeight(constraints), equals(0.0));
-    expect(box.getMaxIntrinsicHeight(constraints), equals(100.0));
 
-    constraints = new BoxConstraints(maxHeight: 400.0);
+    expect(box.getMaxIntrinsicWidth(200.0), 400.0);
-    expect(box.getMinIntrinsicWidth(constraints), equals(0.0));
+    expect(box.getMaxIntrinsicWidth(400.0), 800.0);
-    expect(box.getMaxIntrinsicWidth(constraints), equals(800.0));
+
-    expect(box.getMinIntrinsicHeight(constraints), equals(0.0));
+    expect(box.getMinIntrinsicHeight(200.0), 100.0);
-    expect(box.getMaxIntrinsicHeight(constraints), equals(400.0));
+    expect(box.getMinIntrinsicHeight(400.0), 200.0);
+
+    expect(box.getMaxIntrinsicHeight(200.0), 100.0);
+    expect(box.getMaxIntrinsicHeight(400.0), 200.0);
+
+    expect(box.getMinIntrinsicWidth(double.INFINITY), 0.0);
+    expect(box.getMaxIntrinsicWidth(double.INFINITY), 0.0);
+    expect(box.getMinIntrinsicHeight(double.INFINITY), 0.0);
+    expect(box.getMaxIntrinsicHeight(double.INFINITY), 0.0);
+  });
+
+  test('Intrinsic sizing 0.5', () {
+    RenderAspectRatio box = new RenderAspectRatio(aspectRatio: 0.5);
+
+    expect(box.getMinIntrinsicWidth(200.0), 100.0);
+    expect(box.getMinIntrinsicWidth(400.0), 200.0);
+
+    expect(box.getMaxIntrinsicWidth(200.0), 100.0);
+    expect(box.getMaxIntrinsicWidth(400.0), 200.0);
+
+    expect(box.getMinIntrinsicHeight(200.0), 400.0);
+    expect(box.getMinIntrinsicHeight(400.0), 800.0);
+
+    expect(box.getMaxIntrinsicHeight(200.0), 400.0);
+    expect(box.getMaxIntrinsicHeight(400.0), 800.0);
+
+    expect(box.getMinIntrinsicWidth(double.INFINITY), 0.0);
+    expect(box.getMaxIntrinsicWidth(double.INFINITY), 0.0);
+    expect(box.getMinIntrinsicHeight(double.INFINITY), 0.0);
+    expect(box.getMaxIntrinsicHeight(double.INFINITY), 0.0);
+  });
+
+  test('Intrinsic sizing 2.0', () {
+    RenderAspectRatio box = new RenderAspectRatio(
+      aspectRatio: 2.0,
+      child: new RenderSizedBox(const Size(90.0, 70.0))
+    );
+
+    expect(box.getMinIntrinsicWidth(200.0), 400.0);
+    expect(box.getMinIntrinsicWidth(400.0), 800.0);
+
+    expect(box.getMaxIntrinsicWidth(200.0), 400.0);
+    expect(box.getMaxIntrinsicWidth(400.0), 800.0);
+
+    expect(box.getMinIntrinsicHeight(200.0), 100.0);
+    expect(box.getMinIntrinsicHeight(400.0), 200.0);
+
+    expect(box.getMaxIntrinsicHeight(200.0), 100.0);
+    expect(box.getMaxIntrinsicHeight(400.0), 200.0);
+
+    expect(box.getMinIntrinsicWidth(double.INFINITY), 90.0);
+    expect(box.getMaxIntrinsicWidth(double.INFINITY), 90.0);
+    expect(box.getMinIntrinsicHeight(double.INFINITY), 70.0);
+    expect(box.getMaxIntrinsicHeight(double.INFINITY), 70.0);
+  });
+
+  test('Intrinsic sizing 0.5', () {
+    RenderAspectRatio box = new RenderAspectRatio(
+      aspectRatio: 0.5,
+      child: new RenderSizedBox(const Size(90.0, 70.0))
+    );
+
+    expect(box.getMinIntrinsicWidth(200.0), 100.0);
+    expect(box.getMinIntrinsicWidth(400.0), 200.0);
+
+    expect(box.getMaxIntrinsicWidth(200.0), 100.0);
+    expect(box.getMaxIntrinsicWidth(400.0), 200.0);
+
+    expect(box.getMinIntrinsicHeight(200.0), 400.0);
+    expect(box.getMinIntrinsicHeight(400.0), 800.0);
+
+    expect(box.getMaxIntrinsicHeight(200.0), 400.0);
+    expect(box.getMaxIntrinsicHeight(400.0), 800.0);
+
+    expect(box.getMinIntrinsicWidth(double.INFINITY), 90.0);
+    expect(box.getMaxIntrinsicWidth(double.INFINITY), 90.0);
+    expect(box.getMinIntrinsicHeight(double.INFINITY), 70.0);
+    expect(box.getMaxIntrinsicHeight(double.INFINITY), 70.0);
   });
 }

packages/flutter/test/rendering/block_test.dart

@@ -1,70 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'package:flutter/rendering.dart';
-import 'package:test/test.dart';
-
-void main() {
-  test('block intrinsics', () {
-    RenderParagraph paragraph = new RenderParagraph(
-      new TextSpan(
-        style: new TextStyle(height: 1.0),
-        text: 'Hello World'
-      )
-    );
-    const BoxConstraints unconstrained = const BoxConstraints();
-    double textWidth = paragraph.getMaxIntrinsicWidth(unconstrained);
-    double oneLineTextHeight = paragraph.getMinIntrinsicHeight(unconstrained);
-    final BoxConstraints constrained = new BoxConstraints(maxWidth: textWidth * 0.9);
-    double wrappedTextWidth = paragraph.getMinIntrinsicWidth(unconstrained);
-    double twoLinesTextHeight = paragraph.getMinIntrinsicHeight(constrained);
-
-    // controls
-    expect(wrappedTextWidth, lessThan(textWidth));
-    expect(paragraph.getMinIntrinsicWidth(unconstrained), equals(wrappedTextWidth));
-    expect(paragraph.getMaxIntrinsicWidth(constrained), equals(constrained.maxWidth));
-
-    expect(oneLineTextHeight, lessThan(twoLinesTextHeight));
-    expect(twoLinesTextHeight, lessThan(oneLineTextHeight * 3.0));
-    expect(paragraph.getMaxIntrinsicHeight(unconstrained), equals(oneLineTextHeight));
-    expect(paragraph.getMaxIntrinsicHeight(constrained), equals(twoLinesTextHeight));
-
-    // test setup
-    RenderBlock testBlock = new RenderBlock(
-      children: <RenderBox>[
-        paragraph,
-      ]
-    );
-    final BoxConstraints empty = new BoxConstraints.tight(Size.zero);
-
-    // vertical block
-    expect(testBlock.getMinIntrinsicWidth(unconstrained), equals(wrappedTextWidth));
-    expect(testBlock.getMinIntrinsicWidth(constrained), equals(wrappedTextWidth));
-    expect(testBlock.getMaxIntrinsicWidth(unconstrained), equals(textWidth));
-    expect(testBlock.getMaxIntrinsicWidth(constrained), equals(constrained.maxWidth));
-    expect(testBlock.getMinIntrinsicHeight(unconstrained), equals(oneLineTextHeight));
-    expect(testBlock.getMinIntrinsicHeight(constrained), equals(twoLinesTextHeight));
-    expect(testBlock.getMaxIntrinsicHeight(unconstrained), equals(oneLineTextHeight));
-    expect(testBlock.getMaxIntrinsicHeight(constrained), equals(twoLinesTextHeight));
-    expect(testBlock.getMinIntrinsicWidth(empty), equals(0.0));
-    expect(testBlock.getMaxIntrinsicWidth(empty), equals(0.0));
-    expect(testBlock.getMinIntrinsicHeight(empty), equals(0.0));
-    expect(testBlock.getMaxIntrinsicHeight(empty), equals(0.0));
-
-    // horizontal block
-    testBlock.mainAxis = Axis.horizontal;
-    expect(testBlock.getMinIntrinsicWidth(unconstrained), equals(textWidth));
-    expect(testBlock.getMinIntrinsicWidth(constrained), equals(constrained.maxWidth));
-    expect(testBlock.getMaxIntrinsicWidth(unconstrained), equals(textWidth));
-    expect(testBlock.getMaxIntrinsicWidth(constrained), equals(constrained.maxWidth));
-    expect(testBlock.getMinIntrinsicHeight(unconstrained), equals(oneLineTextHeight));
-    expect(testBlock.getMinIntrinsicHeight(constrained), equals(oneLineTextHeight));
-    expect(testBlock.getMaxIntrinsicHeight(unconstrained), equals(oneLineTextHeight));
-    expect(testBlock.getMaxIntrinsicHeight(constrained), equals(oneLineTextHeight));
-    expect(testBlock.getMinIntrinsicWidth(empty), equals(0.0));
-    expect(testBlock.getMaxIntrinsicWidth(empty), equals(0.0));
-    expect(testBlock.getMinIntrinsicHeight(empty), equals(0.0));
-    expect(testBlock.getMaxIntrinsicHeight(empty), equals(0.0));
-  });
-}

packages/flutter/test/rendering/flex_test.dart

@@ -35,10 +35,10 @@ void main() {
     BoxConstraints viewport = new BoxConstraints(maxHeight: 100.0, maxWidth: 100.0);
     layout(flex, constraints: viewport);
     expect(flexible.size.height, equals(0.0));
-    expect(flex.getMinIntrinsicHeight(viewport), equals(100.0));
+    expect(flex.getMinIntrinsicHeight(100.0), equals(200.0));
-    expect(flex.getMaxIntrinsicHeight(viewport), equals(100.0));
+    expect(flex.getMaxIntrinsicHeight(100.0), equals(200.0));
-    expect(flex.getMinIntrinsicWidth(viewport), equals(100.0));
+    expect(flex.getMinIntrinsicWidth(100.0), equals(0.0));
-    expect(flex.getMaxIntrinsicWidth(viewport), equals(100.0));
+    expect(flex.getMaxIntrinsicWidth(100.0), equals(0.0));
   });
 
   test('Horizontal Overflow', () {
@@ -57,10 +57,10 @@ void main() {
     BoxConstraints viewport = new BoxConstraints(maxHeight: 100.0, maxWidth: 100.0);
     layout(flex, constraints: viewport);
     expect(flexible.size.width, equals(0.0));
-    expect(flex.getMinIntrinsicHeight(viewport), equals(100.0));
+    expect(flex.getMinIntrinsicHeight(100.0), equals(0.0));
-    expect(flex.getMaxIntrinsicHeight(viewport), equals(100.0));
+    expect(flex.getMaxIntrinsicHeight(100.0), equals(0.0));
-    expect(flex.getMinIntrinsicWidth(viewport), equals(100.0));
+    expect(flex.getMinIntrinsicWidth(100.0), equals(200.0));
-    expect(flex.getMaxIntrinsicWidth(viewport), equals(100.0));
+    expect(flex.getMaxIntrinsicWidth(100.0), equals(200.0));
   });
 
   test('Vertical Flipped Constraints', () {
@@ -72,7 +72,7 @@ void main() {
     );
     BoxConstraints viewport = new BoxConstraints(maxHeight: 200.0, maxWidth: 1000.0);
     layout(flex, constraints: viewport);
-    expect(flex.getMaxIntrinsicWidth(viewport) , equals(1000.0));
+    expect(flex.getMaxIntrinsicWidth(200.0), equals(0.0));
   });
 
   // We can't right a horizontal version of the above test due to

packages/flutter/test/rendering/intrinsic_width_test.dart

@@ -7,29 +7,30 @@ import 'package:test/test.dart';
 
 import 'rendering_tester.dart';
 
+// before using this, consider using RenderSizedBox from rendering_tester.dart
 class RenderTestBox extends RenderBox {
   RenderTestBox(this._intrinsicDimensions);
 
   final BoxConstraints _intrinsicDimensions;
 
   @override
-  double getMinIntrinsicWidth(BoxConstraints constraints) {
+  double getMinIntrinsicWidth(double height) {
-    return constraints.constrainWidth(_intrinsicDimensions.minWidth);
+    return _intrinsicDimensions.minWidth;
   }
 
   @override
-  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+  double getMaxIntrinsicWidth(double height) {
-    return constraints.constrainWidth(_intrinsicDimensions.maxWidth);
+    return _intrinsicDimensions.maxWidth;
   }
 
   @override
-  double getMinIntrinsicHeight(BoxConstraints constraints) {
+  double getMinIntrinsicHeight(double width) {
-    return constraints.constrainHeight(_intrinsicDimensions.minHeight);
+    return _intrinsicDimensions.minHeight;
   }
 
   @override
-  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+  double getMaxIntrinsicHeight(double width) {
-    return constraints.constrainHeight(_intrinsicDimensions.maxHeight);
+    return _intrinsicDimensions.maxHeight;
   }
 
   @override

packages/flutter/test/rendering/paragraph_intrinsics_test.dart

@@ -0,0 +1,68 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/rendering.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('block and paragraph intrinsics', () {
+    final RenderParagraph paragraph = new RenderParagraph(
+      new TextSpan(
+        style: new TextStyle(height: 1.0),
+        text: 'Hello World'
+      )
+    );
+    final RenderBlock testBlock = new RenderBlock(
+      children: <RenderBox>[
+        paragraph,
+      ]
+    );
+
+    final double textWidth = paragraph.getMaxIntrinsicWidth(double.INFINITY);
+    final double oneLineTextHeight = paragraph.getMinIntrinsicHeight(double.INFINITY);
+    final double constrainedWidth = textWidth * 0.9;
+    final double wrappedTextWidth = paragraph.getMinIntrinsicWidth(double.INFINITY);
+    final double twoLinesTextHeight = paragraph.getMinIntrinsicHeight(constrainedWidth);
+    final double manyLinesTextHeight = paragraph.getMinIntrinsicHeight(0.0);
+
+    // paragraph
+    expect(wrappedTextWidth, greaterThan(0.0));
+    expect(wrappedTextWidth, lessThan(textWidth));
+    expect(oneLineTextHeight, lessThan(twoLinesTextHeight));
+    expect(twoLinesTextHeight, lessThan(oneLineTextHeight * 3.0));
+    expect(manyLinesTextHeight, greaterThan(twoLinesTextHeight));
+    expect(paragraph.getMaxIntrinsicHeight(double.INFINITY), equals(oneLineTextHeight));
+    expect(paragraph.getMaxIntrinsicHeight(constrainedWidth), equals(twoLinesTextHeight));
+    expect(paragraph.getMaxIntrinsicHeight(0.0), equals(manyLinesTextHeight));
+
+    // vertical block (same expectations)
+    expect(testBlock.getMinIntrinsicWidth(double.INFINITY), equals(wrappedTextWidth));
+    expect(testBlock.getMaxIntrinsicWidth(double.INFINITY), equals(textWidth));
+    expect(testBlock.getMinIntrinsicHeight(double.INFINITY), equals(oneLineTextHeight));
+    expect(testBlock.getMinIntrinsicHeight(constrainedWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(double.INFINITY), equals(oneLineTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(constrainedWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMinIntrinsicWidth(0.0), equals(wrappedTextWidth));
+    expect(testBlock.getMaxIntrinsicWidth(0.0), equals(textWidth));
+    expect(testBlock.getMinIntrinsicHeight(wrappedTextWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(wrappedTextWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMinIntrinsicHeight(0.0), equals(manyLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(0.0), equals(manyLinesTextHeight));
+
+    // horizontal block (same expectations again)
+    testBlock.mainAxis = Axis.horizontal;
+    expect(testBlock.getMinIntrinsicWidth(double.INFINITY), equals(wrappedTextWidth));
+    expect(testBlock.getMaxIntrinsicWidth(double.INFINITY), equals(textWidth));
+    expect(testBlock.getMinIntrinsicHeight(double.INFINITY), equals(oneLineTextHeight));
+    expect(testBlock.getMinIntrinsicHeight(constrainedWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(double.INFINITY), equals(oneLineTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(constrainedWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMinIntrinsicWidth(0.0), equals(wrappedTextWidth));
+    expect(testBlock.getMaxIntrinsicWidth(0.0), equals(textWidth));
+    expect(testBlock.getMinIntrinsicHeight(wrappedTextWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(wrappedTextWidth), equals(twoLinesTextHeight));
+    expect(testBlock.getMinIntrinsicHeight(0.0), equals(manyLinesTextHeight));
+    expect(testBlock.getMaxIntrinsicHeight(0.0), equals(manyLinesTextHeight));
+  });
+}

packages/flutter/test/rendering/rendering_tester.dart

@@ -91,7 +91,33 @@ class RenderSizedBox extends RenderBox {
   final Size _size;
 
   @override
-  void performLayout() {
+  double getMinIntrinsicWidth(double height) {
+    return _size.width;
+  }
+
+  @override
+  double getMaxIntrinsicWidth(double height) {
+    return _size.width;
+  }
+
+  @override
+  double getMinIntrinsicHeight(double width) {
+    return _size.height;
+  }
+
+  @override
+  double getMaxIntrinsicHeight(double width) {
+    return _size.height;
+  }
+
+  @override
+  bool get sizedByParent => true;
+
+  @override
+  void performResize() {
     size = constraints.constrain(_size);
   }
+
+  @override
+  void performLayout() { }
 }