firka/flutter
firka/flutter
4
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #763 from abarth/scroll_gravity

Browse Source 
Cleanup how we manage scrollOffset in Scrollable
This commit is contained in:
Adam Barth 2015-08-21 17:06:13 -07:00
commit dc7137b0ba
3 changed files with 71 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
packages/flutter/lib/animation/scroll_behavior.dart
View File

@ -17,32 +17,33 @@ abstract class ScrollBehavior {
class BoundedBehavior extends ScrollBehavior {
BoundedBehavior({ double contentsSize: 0.0, double containerSize: 0.0 })
: _contentsSize = contentsSize,
_containerSize = containerSize;
: _contentsExtents = contentsSize,
_containerExtents = containerSize;
double _contentsSize;
double get contentsSize => _contentsSize;
void set contentsSize (double value) {
if (_contentsSize != value) {
_contentsSize = value;
// TODO(ianh) now what? what if we have a simulation ongoing?
}
}
double _contentsExtents;
double get contentsExtents => _contentsExtents;
double _containerSize;
double get containerSize => _containerSize;
void set containerSize (double value) {
if (_containerSize != value) {
_containerSize = value;
// TODO(ianh) now what? what if we have a simulation ongoing?
}
double _containerExtents;
double get containerExtents => _containerExtents;
/// Returns the new scrollOffset.
double updateExtents({
double contentsExtents,
double containerExtents,
double scrollOffset: 0.0
}) {
if (contentsExtents != null)
_contentsExtents = contentsExtents;
if (containerExtents != null)
_containerExtents = containerExtents;
return scrollOffset.clamp(minScrollOffset, maxScrollOffset);
}
final double minScrollOffset = 0.0;
double get maxScrollOffset => math.max(0.0, _contentsSize - _containerSize);
double get maxScrollOffset => math.max(0.0, _contentsExtents - _containerExtents);
double applyCurve(double scrollOffset, double scrollDelta) {
return (scrollOffset + scrollDelta).clamp(0.0, maxScrollOffset);
return (scrollOffset + scrollDelta).clamp(minScrollOffset, maxScrollOffset);
}
}
@ -80,7 +81,7 @@ class OverscrollBehavior extends BoundedBehavior {
}
class OverscrollWhenScrollableBehavior extends OverscrollBehavior {
bool get isScrollable => contentsSize > containerSize;
bool get isScrollable => contentsExtents > containerExtents;
Simulation release(double position, double velocity) {
if (isScrollable || position < minScrollOffset || position > maxScrollOffset)

98
packages/flutter/lib/widgets/scrollable.dart
View File

@ -22,7 +22,6 @@ import 'package:sky/widgets/scrollable.dart';
export 'package:sky/widgets/mixed_viewport.dart' show MixedViewportLayoutState;
// The GestureEvent velocity properties are pixels/second, config min,max limits are pixels/ms
const double _kMillisecondsPerSecond = 1000.0;
const double _kMinFlingVelocity = -config.kMaxFlingVelocity * _kMillisecondsPerSecond;
@ -48,11 +47,11 @@ abstract class Scrollable extends StatefulComponent {
ValueAnimation<double> _toOffsetAnimation; // Started by scrollTo()
void initState() {
_toEndAnimation = new AnimatedSimulation(_tickScrollOffset);
_toEndAnimation = new AnimatedSimulation(_setScrollOffset);
_toOffsetAnimation = new ValueAnimation<double>()
..addListener(() {
AnimatedValue<double> offset = _toOffsetAnimation.variable;
scrollTo(offset.value);
_setScrollOffset(offset.value);
});
}
@ -93,8 +92,7 @@ abstract class Scrollable extends StatefulComponent {
}
Future _startToOffsetAnimation(double newScrollOffset, Duration duration, Curve curve) {
_stopToEndAnimation();
_stopToOffsetAnimation();
_stopAnimations();
_toOffsetAnimation
..variable = new AnimatedValue<double>(scrollOffset,
end: newScrollOffset,
@ -105,47 +103,46 @@ abstract class Scrollable extends StatefulComponent {
return _toOffsetAnimation.play();
}
void _stopToOffsetAnimation() {
void _stopAnimations() {
if (_toOffsetAnimation.isAnimating)
_toOffsetAnimation.stop();
if (_toEndAnimation.isAnimating)
_toEndAnimation.stop();
}
void _startToEndAnimation({ double velocity: 0.0 }) {
_stopToEndAnimation();
_stopToOffsetAnimation();
_stopAnimations();
Simulation simulation = scrollBehavior.release(scrollOffset, velocity);
if (simulation != null)
_toEndAnimation.start(simulation);
}
void _stopToEndAnimation() {
_toEndAnimation.stop();
void didUnmount() {
_stopAnimations();
super.didUnmount();
}
void didUnmount() {
_stopToEndAnimation();
_stopToOffsetAnimation();
super.didUnmount();
void _setScrollOffset(double newScrollOffset) {
if (_scrollOffset == newScrollOffset)
return;
setState(() {
_scrollOffset = newScrollOffset;
});
if (_listeners.length > 0)
_notifyListeners();
}
Future scrollTo(double newScrollOffset, { Duration duration, Curve curve: ease }) {
if (newScrollOffset == _scrollOffset)
return new Future.value();
Future result;
if (duration == null) {
setState(() {
_scrollOffset = newScrollOffset;
});
result = new Future.value();
} else {
result = _startToOffsetAnimation(newScrollOffset, duration, curve);
_stopAnimations();
_setScrollOffset(newScrollOffset);
return new Future.value();
}
if (_listeners.length > 0)
_notifyListeners();
return result;
return _startToOffsetAnimation(newScrollOffset, duration, curve);
}
Future scrollBy(double scrollDelta, { Duration duration, Curve curve }) {
@ -157,10 +154,6 @@ abstract class Scrollable extends StatefulComponent {
_startToEndAnimation();
}
void _tickScrollOffset(double value) {
scrollTo(value);
}
// Return the event's velocity in pixels/second.
double _eventVelocity(sky.GestureEvent event) {
double velocity = scrollDirection == ScrollDirection.horizontal
@ -170,8 +163,7 @@ abstract class Scrollable extends StatefulComponent {
}
EventDisposition _handlePointerDown(_) {
_stopToEndAnimation();
_stopToOffsetAnimation();
_stopAnimations();
return EventDisposition.processed;
}
@ -293,10 +285,10 @@ class ScrollableViewport extends Scrollable {
_updateScrollBehaviour();
}
void _updateScrollBehaviour() {
scrollBehavior.contentsSize = _childSize;
scrollBehavior.containerSize = _viewportSize;
if (scrollOffset > scrollBehavior.maxScrollOffset)
settleScrollOffset();
scrollTo(scrollBehavior.updateExtents(
contentsExtents: _childSize,
containerExtents: _viewportSize,
scrollOffset: scrollOffset));
}
Widget buildContent() {
@ -375,6 +367,11 @@ abstract class ScrollableWidgetList extends Scrollable {
itemExtent = source.itemExtent;
super.syncFields(source); // update scrollDirection
if (itemCount != _previousItemCount) {
scrollBehaviorUpdateNeeded = true;
_previousItemCount = itemCount;
}
if (scrollBehaviorUpdateNeeded)
_updateScrollBehavior();
}
@ -416,17 +413,14 @@ abstract class ScrollableWidgetList extends Scrollable {
}
void _updateScrollBehavior() {
scrollBehavior.containerSize = _containerExtent;
double contentsExtent = itemExtent * itemCount;
if (padding != null)
contentsExtent += _leadingPadding + _trailingPadding;
scrollBehavior.contentsSize = contentsExtent;
}
void _updateScrollOffset() {
if (scrollOffset > scrollBehavior.maxScrollOffset)
settleScrollOffset();
scrollTo(scrollBehavior.updateExtents(
contentsExtents: contentsExtent,
containerExtents: _containerExtent,
scrollOffset: scrollOffset));
}
Offset _toOffset(double value) {
@ -439,7 +433,6 @@ abstract class ScrollableWidgetList extends Scrollable {
if (itemCount != _previousItemCount) {
_previousItemCount = itemCount;
_updateScrollBehavior();
_updateScrollOffset();
}
double paddedScrollOffset = scrollOffset;
@ -643,18 +636,19 @@ class ScrollableMixedWidgetList extends Scrollable {
OverscrollBehavior get scrollBehavior => super.scrollBehavior;
void _handleSizeChanged(Size newSize) {
scrollBehavior.containerSize = newSize.height;
scrollBy(scrollBehavior.updateExtents(
containerExtents: newSize.height,
scrollOffset: scrollOffset
));
}
void _handleLayoutChanged() {
if (layoutState.didReachLastChild) {
scrollBehavior.contentsSize = layoutState.contentsSize;
if (_contentsChanged && scrollOffset > scrollBehavior.maxScrollOffset) {
_contentsChanged = false;
settleScrollOffset();
}
} else {
scrollBehavior.contentsSize = double.INFINITY;
double newScrollOffset = scrollBehavior.updateExtents(
contentsExtents: layoutState.didReachLastChild ? layoutState.contentsSize : double.INFINITY,
scrollOffset: scrollOffset);
if (_contentsChanged) {
_contentsChanged = false;
scrollTo(newScrollOffset);
}
}

7
packages/flutter/lib/widgets/tabs.dart
View File

@ -460,7 +460,7 @@ class TabBar extends Scrollable {
}
double _centeredTabScrollOffset(int tabIndex) {
double viewportWidth = scrollBehavior.containerSize;
double viewportWidth = scrollBehavior.containerExtents;
return (_tabRect(tabIndex).left + _tabWidths[tabIndex] / 2.0 - viewportWidth / 2.0)
.clamp(scrollBehavior.minScrollOffset, scrollBehavior.maxScrollOffset);
}
@ -495,8 +495,9 @@ class TabBar extends Scrollable {
setState(() {
_tabBarSize = tabBarSize;
_tabWidths = tabWidths;
scrollBehavior.containerSize = _tabBarSize.width;
scrollBehavior.contentsSize = _tabWidths.reduce((sum, width) => sum + width);
scrollBehavior.updateExtents(
containerExtents: _tabBarSize.width,
contentsExtents: _tabWidths.reduce((sum, width) => sum + width));
});
}