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Handle changes to scrollDirection in ScrollableList et al
Changed the pageable_list.dart example: tapping on the toolbar changes the scroll direction. This exposed some problems: - Scrollable.syncFields() didn't update scrollDirection - Viewport updated its RenderObject fields in the wrong order - FixedHeightScrollable scrollDirection changes didn't update the scrollBehavior There may be similar problems with VariableHeightList and ScrollableViewport. I will fix those in a separate CL.
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72807ef8ec
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@ -24,13 +24,14 @@ class CardModel {
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Key get key => new Key.fromObjectIdentity(this);
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}
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class TestApp extends App {
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class PageableListApp extends App {
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static const TextStyle cardLabelStyle =
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const TextStyle(color: white, fontSize: 18.0, fontWeight: bold);
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List<CardModel> cardModels;
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Size pageSize = new Size(200.0, 200.0);
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ScrollDirection scrollDirection = ScrollDirection.horizontal;
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void initState() {
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List<Size> cardSizes = [
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@ -55,6 +56,15 @@ class TestApp extends App {
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});
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}
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EventDisposition handleToolbarTap(_) {
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setState(() {
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scrollDirection = (scrollDirection == ScrollDirection.vertical)
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? ScrollDirection.horizontal
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: ScrollDirection.vertical;
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});
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return EventDisposition.processed;
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}
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Widget buildCard(CardModel cardModel) {
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Widget card = new Card(
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color: cardModel.color,
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@ -65,9 +75,14 @@ class TestApp extends App {
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child: new Center(child: new Text(cardModel.label, style: cardLabelStyle))
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)
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);
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BoxConstraints constraints = (scrollDirection == ScrollDirection.vertical)
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? new BoxConstraints.tightFor(height: pageSize.height)
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: new BoxConstraints.tightFor(width: pageSize.width);
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return new Container(
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key: cardModel.key,
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width: pageSize.width,
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constraints: constraints,
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child: new Center(child: card)
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);
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}
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@ -76,8 +91,10 @@ class TestApp extends App {
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Widget list = new PageableList<CardModel>(
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items: cardModels,
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itemBuilder: buildCard,
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scrollDirection: ScrollDirection.horizontal,
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itemExtent: pageSize.width
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scrollDirection: scrollDirection,
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itemExtent: (scrollDirection == ScrollDirection.vertical)
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? pageSize.height
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: pageSize.width
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);
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return new IconTheme(
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@ -91,7 +108,10 @@ class TestApp extends App {
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child: new TaskDescription(
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label: 'PageableList',
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child: new Scaffold(
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toolbar: new ToolBar(center: new Text('PageableList Demo')),
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toolbar: new Listener(
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onGestureTap: handleToolbarTap,
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child: new ToolBar(center: new Text('PageableList: ${scrollDirection}'))
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),
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body: new SizeObserver(
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callback: updatePageSize,
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child: new Container(
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@ -107,5 +127,5 @@ class TestApp extends App {
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}
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void main() {
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runApp(new TestApp());
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runApp(new PageableListApp());
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}
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@ -285,21 +285,22 @@ class Baseline extends OneChildRenderObjectWrapper {
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class Viewport extends OneChildRenderObjectWrapper {
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Viewport({
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Key key,
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this.scrollOffset: Offset.zero,
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this.scrollDirection: ScrollDirection.vertical,
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this.scrollOffset: Offset.zero,
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Widget child
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}) : super(key: key, child: child);
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final Offset scrollOffset;
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final ScrollDirection scrollDirection;
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final Offset scrollOffset;
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RenderViewport createNode() => new RenderViewport(scrollOffset: scrollOffset, scrollDirection: scrollDirection);
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RenderViewport createNode() => new RenderViewport(scrollDirection: scrollDirection, scrollOffset: scrollOffset);
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RenderViewport get renderObject => super.renderObject;
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void syncRenderObject(Viewport old) {
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super.syncRenderObject(old);
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renderObject.scrollOffset = scrollOffset;
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// Order dependency: RenderViewport validates scrollOffset based on scrollDirection.
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renderObject.scrollDirection = scrollDirection;
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renderObject.scrollOffset = scrollOffset;
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}
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}
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@ -57,7 +57,7 @@ abstract class Scrollable extends StatefulComponent {
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}
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void syncFields(Scrollable source) {
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scrollDirection == source.scrollDirection;
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scrollDirection = source.scrollDirection;
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}
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double _scrollOffset = 0.0;
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@ -358,6 +358,7 @@ abstract class FixedHeightScrollable extends Scrollable {
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EdgeDims padding;
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double itemExtent;
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Size containerSize = Size.zero;
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/// Subclasses must implement `get itemCount` to tell FixedHeightScrollable
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/// how many items there are in the list.
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@ -365,22 +366,32 @@ abstract class FixedHeightScrollable extends Scrollable {
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int _previousItemCount;
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void syncFields(FixedHeightScrollable source) {
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if (padding != source.padding || itemExtent != source.itemExtent) {
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padding = source.padding;
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itemExtent = source.itemExtent;
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_updateContentsExtent();
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}
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super.syncFields(source);
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bool scrollBehaviorUpdateNeeded =
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padding != source.padding ||
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itemExtent != source.itemExtent ||
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scrollDirection != source.scrollDirection;
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padding = source.padding;
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itemExtent = source.itemExtent;
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super.syncFields(source); // update scrollDirection
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if (scrollBehaviorUpdateNeeded)
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_updateScrollBehavior();
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}
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ScrollBehavior createScrollBehavior() => new OverscrollBehavior();
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OverscrollBehavior get scrollBehavior => super.scrollBehavior;
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double _containerExtent;
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double get _containerExtent {
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return scrollDirection == ScrollDirection.vertical
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? containerSize.height
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: containerSize.width;
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}
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void _handleSizeChanged(Size newSize) {
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setState(() {
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_containerExtent = scrollDirection == ScrollDirection.vertical ? newSize.height : newSize.width;
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scrollBehavior.containerSize = _containerExtent;
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containerSize = newSize;
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_updateScrollBehavior();
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});
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}
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@ -404,7 +415,9 @@ abstract class FixedHeightScrollable extends Scrollable {
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return new EdgeDims.only(top: padding.top, bottom: padding.bottom);
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}
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void _updateContentsExtent() {
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void _updateScrollBehavior() {
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scrollBehavior.containerSize = _containerExtent;
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double contentsExtent = itemExtent * itemCount;
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if (padding != null)
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contentsExtent += _leadingPadding + _trailingPadding;
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@ -425,7 +438,7 @@ abstract class FixedHeightScrollable extends Scrollable {
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Widget buildContent() {
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if (itemCount != _previousItemCount) {
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_previousItemCount = itemCount;
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_updateContentsExtent();
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_updateScrollBehavior();
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_updateScrollOffset();
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}
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