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Merge pull request #494 from abarth/integer_scrolling

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RenderViewport should use integer device pixels
This commit is contained in:
Adam Barth 2015-08-07 09:52:14 -07:00
commit fb512aa604
1 changed files with 12 additions and 3 deletions
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15
packages/flutter/lib/rendering/box.dart
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@ -1238,15 +1238,24 @@ class RenderViewport extends RenderBox with RenderObjectWithChildMixin<RenderBox
}
}
Offset get _scrollOffsetRoundedToIntegerDevicePixels {
double devicePixelRatio = sky.view.devicePixelRatio;
int dxInDevicePixels = (scrollOffset.dx * devicePixelRatio).round();
int dyInDevicePixels = (scrollOffset.dy * devicePixelRatio).round();
return new Offset(dxInDevicePixels / devicePixelRatio,
dyInDevicePixels / devicePixelRatio);
}
void paint(PaintingCanvas canvas, Offset offset) {
if (child != null) {
Offset roundedScrollOffset = _scrollOffsetRoundedToIntegerDevicePixels;
bool _needsClip = offset < Offset.zero ||
!(offset & size).contains(((offset - scrollOffset) & child.size).bottomRight);
!(offset & size).contains(((offset - roundedScrollOffset) & child.size).bottomRight);
if (_needsClip) {
canvas.save();
canvas.clipRect(offset & size);
}
canvas.paintChild(child, (offset - scrollOffset).toPoint());
canvas.paintChild(child, (offset - roundedScrollOffset).toPoint());
if (_needsClip)
canvas.restore();
}
@ -1256,7 +1265,7 @@ class RenderViewport extends RenderBox with RenderObjectWithChildMixin<RenderBox
if (child != null) {
assert(child.parentData is BoxParentData);
Rect childBounds = child.parentData.position & child.size;
Point transformedPosition = position + scrollOffset;
Point transformedPosition = position + _scrollOffsetRoundedToIntegerDevicePixels;
if (childBounds.contains(transformedPosition))
child.hitTest(result, position: transformedPosition);
}