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

// Copyright 2014 The Flutter 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 'box.dart';
import 'object.dart';

export 'package:flutter/foundation.dart' show debugPrint;

// Any changes to this file should be reflected in the debugAssertAllRenderVarsUnset()
// function below.

const HSVColor _kDebugDefaultRepaintColor = HSVColor.fromAHSV(0.4, 60.0, 1.0, 1.0);

/// Causes each RenderBox to paint a box around its bounds, and some extra
/// boxes, such as [RenderPadding], to draw construction lines.
///
/// The edges of the boxes are painted as a one-pixel-thick `const Color(0xFF00FFFF)` outline.
///
/// Spacing is painted as a solid `const Color(0x90909090)` area.
///
/// Padding is filled in solid `const Color(0x900090FF)`, with the inner edge
/// outlined in `const Color(0xFF0090FF)`, using [debugPaintPadding].
bool debugPaintSizeEnabled = false;

/// Causes each RenderBox to paint a line at each of its baselines.
bool debugPaintBaselinesEnabled = false;

/// Causes each Layer to paint a box around its bounds.
bool debugPaintLayerBordersEnabled = false;

/// Causes objects like [RenderPointerListener] to flash while they are being
/// tapped. This can be useful to see how large the hit box is, e.g. when
/// debugging buttons that are harder to hit than expected.
///
/// For details on how to support this in your [RenderBox] subclass, see
/// [RenderBox.debugHandleEvent].
bool debugPaintPointersEnabled = false;

/// Overlay a rotating set of colors when repainting layers in debug mode.
///
/// See also:
///
///  * [RepaintBoundary], which can be used to contain repaints when unchanged
///    areas are being excessively repainted.
bool debugRepaintRainbowEnabled = false;

/// Overlay a rotating set of colors when repainting text in debug mode.
bool debugRepaintTextRainbowEnabled = false;

/// The current color to overlay when repainting a layer.
///
/// This is used by painting debug code that implements
/// [debugRepaintRainbowEnabled] or [debugRepaintTextRainbowEnabled].
///
/// The value is incremented by [RenderView.compositeFrame] if either of those
/// flags is enabled.
HSVColor debugCurrentRepaintColor = _kDebugDefaultRepaintColor;

/// Log the call stacks that mark render objects as needing layout.
///
/// For sanity, this only logs the stack traces of cases where an object is
/// added to the list of nodes needing layout. This avoids printing multiple
/// redundant stack traces as a single [RenderObject.markNeedsLayout] call walks
/// up the tree.
bool debugPrintMarkNeedsLayoutStacks = false;

/// Log the call stacks that mark render objects as needing paint.
bool debugPrintMarkNeedsPaintStacks = false;

/// Log the dirty render objects that are laid out each frame.
///
/// Combined with [debugPrintBeginFrameBanner], this allows you to distinguish
/// layouts triggered by the initial mounting of a render tree (e.g. in a call
/// to [runApp]) from the regular layouts triggered by the pipeline.
///
/// Combined with [debugPrintMarkNeedsLayoutStacks], this lets you watch a
/// render object's dirty/clean lifecycle.
///
/// See also:
///
///  * [debugProfileLayoutsEnabled], which does something similar for layout
///    but using the timeline view.
///  * [debugProfilePaintsEnabled], which does something similar for painting
///    but using the timeline view.
///  * [debugPrintRebuildDirtyWidgets], which does something similar for widgets
///    being rebuilt.
///  * The discussion at [RendererBinding.drawFrame].
bool debugPrintLayouts = false;

/// Check the intrinsic sizes of each [RenderBox] during layout.
///
/// By default this is turned off since these checks are expensive. If you are
/// implementing your own children of [RenderBox] with custom intrinsics, turn
/// this on in your unit tests for additional validations.
bool debugCheckIntrinsicSizes = false;

/// Adds [Timeline] events for every [RenderObject] layout.
///
/// The timing information this flag exposes is not representative of the actual
/// cost of layout, because the overhead of adding timeline events is
/// significant relative to the time each object takes to lay out. However, it
/// can expose unexpected layout behavior in the timeline.
///
/// In debug builds, additional information is included in the trace (such as
/// the properties of render objects being laid out). Collecting this data is
/// expensive and further makes these traces non-representative of actual
/// performance. This data is omitted in profile builds.
///
/// For more information about performance debugging in Flutter, see
/// <https://docs.flutter.dev/perf/ui-performance>.
///
/// See also:
///
///  * [debugPrintLayouts], which does something similar for layout but using
///    console output.
///  * [debugProfileBuildsEnabled], which does something similar for widgets
///    being rebuilt.
///  * [debugProfilePaintsEnabled], which does something similar for painting.
///  * [debugEnhanceLayoutTimelineArguments], which enhances the trace with
///    debugging information related to [RenderObject] layouts.
bool debugProfileLayoutsEnabled = false;

/// Adds [Timeline] events for every [RenderObject] painted.
///
/// The timing information this flag exposes is not representative of actual
/// paints, because the overhead of adding timeline events is significant
/// relative to the time each object takes to paint. However, it can expose
/// unexpected painting in the timeline.
///
/// In debug builds, additional information is included in the trace (such as
/// the properties of render objects being painted). Collecting this data is
/// expensive and further makes these traces non-representative of actual
/// performance. This data is omitted in profile builds.
///
/// For more information about performance debugging in Flutter, see
/// <https://docs.flutter.dev/perf/ui-performance>.
///
/// See also:
///
///  * [debugProfileBuildsEnabled], which does something similar for widgets
///    being rebuilt, and [debugPrintRebuildDirtyWidgets], its console
///    equivalent.
///  * [debugProfileLayoutsEnabled], which does something similar for layout,
///    and [debugPrintLayouts], its console equivalent.
///  * The discussion at [RendererBinding.drawFrame].
///  * [RepaintBoundary], which can be used to contain repaints when unchanged
///    areas are being excessively repainted.
///  * [debugEnhancePaintTimelineArguments], which enhances the trace with
///    debugging information related to [RenderObject] paints.
bool debugProfilePaintsEnabled = false;

/// Adds debugging information to [Timeline] events related to [RenderObject]
/// layouts.
///
/// This flag will only add [Timeline] event arguments for debug builds.
/// Additional arguments will be added for the "LAYOUT" timeline event and for
/// all [RenderObject] layout [Timeline] events, which are the events that are
/// added when [debugProfileLayoutsEnabled] is true. The debugging information
/// that will be added in trace arguments includes stats around [RenderObject]
/// dirty states and [RenderObject] diagnostic information (i.e. [RenderObject]
/// properties).
///
/// See also:
///
///  * [debugProfileLayoutsEnabled], which adds [Timeline] events for every
///    [RenderObject] layout.
///  * [debugEnhancePaintTimelineArguments], which does something similar for
///    events related to [RenderObject] paints.
///  * [debugEnhanceBuildTimelineArguments], which does something similar for
///    events related to [Widget] builds.
bool debugEnhanceLayoutTimelineArguments = false;

/// Adds debugging information to [Timeline] events related to [RenderObject]
/// paints.
///
/// This flag will only add [Timeline] event arguments for debug builds.
/// Additional arguments will be added for the "PAINT" timeline event and for
/// all [RenderObject] paint [Timeline] events, which are the [Timeline] events
/// that are added when [debugProfilePaintsEnabled] is true. The debugging
/// information that will be added in trace arguments includes stats around
/// [RenderObject] dirty states and [RenderObject] diagnostic information
/// (i.e. [RenderObject] properties).
///
/// See also:
///
///  * [debugProfilePaintsEnabled], which adds [Timeline] events for every
///    [RenderObject] paint.
///  * [debugEnhanceLayoutTimelineArguments], which does something similar for
///    events related to [RenderObject] layouts.
///  * [debugEnhanceBuildTimelineArguments], which does something similar for
///    events related to [Widget] builds.
bool debugEnhancePaintTimelineArguments = false;

/// Signature for [debugOnProfilePaint] implementations.
typedef ProfilePaintCallback = void Function(RenderObject renderObject);

/// Callback invoked for every [RenderObject] painted each frame.
///
/// This callback is only invoked in debug builds.
///
/// See also:
///
///  * [debugProfilePaintsEnabled], which does something similar but adds
///    [dart:developer.Timeline] events instead of invoking a callback.
///  * [debugOnRebuildDirtyWidget], which does something similar for widgets
///    being built.
///  * [WidgetInspectorService], which uses the [debugOnProfilePaint]
///    callback to generate aggregate profile statistics describing what paints
///    occurred when the `ext.flutter.inspector.trackRepaintWidgets` service
///    extension is enabled.
ProfilePaintCallback? debugOnProfilePaint;

/// Setting to true will cause all clipping effects from the layer tree to be
/// ignored.
///
/// Can be used to debug whether objects being clipped are painting excessively
/// in clipped areas. Can also be used to check whether excessive use of
/// clipping is affecting performance.
///
/// This will not reduce the number of [Layer] objects created; the compositing
/// strategy is unaffected. It merely causes the clipping layers to be skipped
/// when building the scene.
bool debugDisableClipLayers = false;

/// Setting to true will cause all physical modeling effects from the layer
/// tree, such as shadows from elevations, to be ignored.
///
/// Can be used to check whether excessive use of physical models is affecting
/// performance.
///
/// This will not reduce the number of [Layer] objects created; the compositing
/// strategy is unaffected. It merely causes the physical shape layers to be
/// skipped when building the scene.
bool debugDisablePhysicalShapeLayers = false;

/// Setting to true will cause all opacity effects from the layer tree to be
/// ignored.
///
/// An optimization to not paint the child at all when opacity is 0 will still
/// remain.
///
/// Can be used to check whether excessive use of opacity effects is affecting
/// performance.
///
/// This will not reduce the number of [Layer] objects created; the compositing
/// strategy is unaffected. It merely causes the opacity layers to be skipped
/// when building the scene.
bool debugDisableOpacityLayers = false;

void _debugDrawDoubleRect(Canvas canvas, Rect outerRect, Rect innerRect, Color color) {
  final Path path = Path()
    ..fillType = PathFillType.evenOdd
    ..addRect(outerRect)
    ..addRect(innerRect);
  final Paint paint = Paint()
    ..color = color;
  canvas.drawPath(path, paint);
}

/// Paint a diagram showing the given area as padding.
///
/// The `innerRect` argument represents the position of the child, if any.
///
/// When `innerRect` is null, the method draws the entire `outerRect` in a
/// grayish color representing _spacing_.
///
/// When `innerRect` is non-null, the method draws the padding region around the
/// `innerRect` in a tealish color, with a solid outline around the inner
/// region.
///
/// This method is used by [RenderPadding.debugPaintSize] when
/// [debugPaintSizeEnabled] is true.
void debugPaintPadding(Canvas canvas, Rect outerRect, Rect? innerRect, { double outlineWidth = 2.0 }) {
  assert(() {
    if (innerRect != null && !innerRect.isEmpty) {
      _debugDrawDoubleRect(canvas, outerRect, innerRect, const Color(0x900090FF));
      _debugDrawDoubleRect(canvas, innerRect.inflate(outlineWidth).intersect(outerRect), innerRect, const Color(0xFF0090FF));
    } else {
      final Paint paint = Paint()
        ..color = const Color(0x90909090);
      canvas.drawRect(outerRect, paint);
    }
    return true;
  }());
}

/// Returns true if none of the rendering library debug variables have been changed.
///
/// This function is used by the test framework to ensure that debug variables
/// haven't been inadvertently changed.
///
/// See [the rendering library](rendering/rendering-library.html) for a complete
/// list.
///
/// The `debugCheckIntrinsicSizesOverride` argument can be provided to override
/// the expected value for [debugCheckIntrinsicSizes]. (This exists because the
/// test framework itself overrides this value in some cases.)
bool debugAssertAllRenderVarsUnset(String reason, { bool debugCheckIntrinsicSizesOverride = false }) {
  assert(() {
    if (debugPaintSizeEnabled ||
        debugPaintBaselinesEnabled ||
        debugPaintLayerBordersEnabled ||
        debugPaintPointersEnabled ||
        debugRepaintRainbowEnabled ||
        debugRepaintTextRainbowEnabled ||
        debugCurrentRepaintColor != _kDebugDefaultRepaintColor ||
        debugPrintMarkNeedsLayoutStacks ||
        debugPrintMarkNeedsPaintStacks ||
        debugPrintLayouts ||
        debugCheckIntrinsicSizes != debugCheckIntrinsicSizesOverride ||
        debugProfileLayoutsEnabled ||
        debugProfilePaintsEnabled ||
        debugOnProfilePaint != null ||
        debugDisableClipLayers ||
        debugDisablePhysicalShapeLayers ||
        debugDisableOpacityLayers) {
      throw FlutterError(reason);
    }
    return true;
  }());
  return true;
}

/// Returns true if the given [Axis] is bounded within the given
/// [BoxConstraints] in both the main and cross axis, throwing an exception
/// otherwise.
///
/// This is used by viewports during `performLayout` and `computeDryLayout`
/// because bounded constraints are required in order to layout their children.
bool debugCheckHasBoundedAxis(Axis axis, BoxConstraints constraints) {
  assert(() {
    if (!constraints.hasBoundedHeight || !constraints.hasBoundedWidth) {
      switch (axis) {
        case Axis.vertical:
          if (!constraints.hasBoundedHeight) {
            throw FlutterError.fromParts(<DiagnosticsNode>[
              ErrorSummary('Vertical viewport was given unbounded height.'),
              ErrorDescription(
                'Viewports expand in the scrolling direction to fill their container. '
                'In this case, a vertical viewport was given an unlimited amount of '
                'vertical space in which to expand. This situation typically happens '
                'when a scrollable widget is nested inside another scrollable widget.',
              ),
              ErrorHint(
                'If this widget is always nested in a scrollable widget there '
                'is no need to use a viewport because there will always be enough '
                'vertical space for the children. In this case, consider using a '
                'Column or Wrap instead. Otherwise, consider using a '
                'CustomScrollView to concatenate arbitrary slivers into a '
                'single scrollable.',
              ),
            ]);
          }
          if (!constraints.hasBoundedWidth) {
            throw FlutterError(
              'Vertical viewport was given unbounded width.\n'
              'Viewports expand in the cross axis to fill their container and '
              'constrain their children to match their extent in the cross axis. '
              'In this case, a vertical viewport was given an unlimited amount of '
              'horizontal space in which to expand.',
            );
          }
        case Axis.horizontal:
          if (!constraints.hasBoundedWidth) {
            throw FlutterError.fromParts(<DiagnosticsNode>[
              ErrorSummary('Horizontal viewport was given unbounded width.'),
              ErrorDescription(
                'Viewports expand in the scrolling direction to fill their container. '
                'In this case, a horizontal viewport was given an unlimited amount of '
                'horizontal space in which to expand. This situation typically happens '
                'when a scrollable widget is nested inside another scrollable widget.',
              ),
              ErrorHint(
                'If this widget is always nested in a scrollable widget there '
                'is no need to use a viewport because there will always be enough '
                'horizontal space for the children. In this case, consider using a '
                'Row or Wrap instead. Otherwise, consider using a '
                'CustomScrollView to concatenate arbitrary slivers into a '
                'single scrollable.',
              ),
            ]);
          }
          if (!constraints.hasBoundedHeight) {
            throw FlutterError(
              'Horizontal viewport was given unbounded height.\n'
              'Viewports expand in the cross axis to fill their container and '
              'constrain their children to match their extent in the cross axis. '
              'In this case, a horizontal viewport was given an unlimited amount of '
              'vertical space in which to expand.',
            );
          }
      }
    }
    return true;
  }());
  return true;
}