firka/flutter
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Fix assert in Stocks app

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When paging a scrollable list, we were trying to read the render object's size
at a time when we're not allowed to read it. Instead, encode the information
into the repaint limit, which is more correct (and faster) anyway.
This commit is contained in:
Adam Barth 2016-01-06 10:44:19 -08:00
parent c4faad115d
commit d2a1389ed0
3 changed files with 3 additions and 12 deletions
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2
packages/flutter/lib/src/widgets/scrollable_grid.dart
View File

@ -142,7 +142,7 @@ class _GridViewportElement extends VirtualViewportElement<GridViewport> {
_materializedChildBase = (materializedRowBase * _specification.columnCount).clamp(0, renderObject.virtualChildCount);
_materializedChildCount = (materializedRowLimit * _specification.columnCount).clamp(0, renderObject.virtualChildCount) - _materializedChildBase;
_repaintOffsetBase = _specification.rowOffsets[materializedRowBase];
_repaintOffsetLimit = _specification.rowOffsets[materializedRowLimit];
_repaintOffsetLimit = _specification.rowOffsets[materializedRowLimit] - containerExtent;
super.layout(constraints);

2
packages/flutter/lib/src/widgets/scrollable_list.dart
View File

@ -170,7 +170,7 @@ class _ListViewportElement extends VirtualViewportElement<ListViewport> {
_materializedChildCount = materializedChildLimit - _materializedChildBase;
_repaintOffsetBase = _materializedChildBase * widget.itemExtent;
_repaintOffsetLimit = materializedChildLimit * widget.itemExtent;
_repaintOffsetLimit = materializedChildLimit * widget.itemExtent - containerExtent;
super.layout(constraints);

11
packages/flutter/lib/src/widgets/virtual_viewport.dart
View File

@ -69,15 +69,6 @@ abstract class VirtualViewportElement<T extends VirtualViewport> extends RenderO
}
}
double get _containerExtent {
switch (widget.scrollDirection) {
case ScrollDirection.vertical:
return renderObject.size.height;
case ScrollDirection.horizontal:
return renderObject.size.width;
}
}
void updateRenderObject() {
renderObject.virtualChildCount = widget.children.length;
@ -89,7 +80,7 @@ abstract class VirtualViewportElement<T extends VirtualViewport> extends RenderO
if (!renderObject.needsLayout) {
if (repaintOffsetBase != null && widget.startOffset < repaintOffsetBase)
renderObject.markNeedsLayout();
else if (repaintOffsetLimit != null && widget.startOffset + _containerExtent > repaintOffsetLimit)
else if (repaintOffsetLimit != null && widget.startOffset > repaintOffsetLimit)
renderObject.markNeedsLayout();
}
}