Subpixel layout: -webkit-flex pushes content off of-by-one pixel.

• Component: Layout and Rendering
• Status: ASSIGNED ---

[zalan]

LayoutTests/css3/flexbox/image-percent-max-height.html

[zalan]

The flexbox layout ends up with different value for the available space (compared to the default layout flow) -> centering the content results in different x pos.

[zalan]

this double rounding is probably unnecessary. The reason why it works when subpixel is off is in that case both layout paths round, one is explicitly while the other is implicitly (due to using only integral px positions).

diff --git a/Source/WebCore/rendering/RenderReplaced.cpp b/Source/WebCore/rendering/RenderReplaced.cpp
index d81b6cb..c0dc7a4 100644
--- a/Source/WebCore/rendering/RenderReplaced.cpp
+++ b/Source/WebCore/rendering/RenderReplaced.cpp
@@ -388,7 +388,7 @@ LayoutUnit RenderReplaced::computeReplacedLogicalWidth(ShouldComputePreferred sh
             // of 'width' is: (used height) * (intrinsic ratio)
             if (intrinsicRatio && ((heightIsAuto && !hasIntrinsicWidth && hasIntrinsicHeight) || !heightIsAuto)) {
                 LayoutUnit logicalHeight = computeReplacedLogicalHeight();
-                return computeReplacedLogicalWidthRespectingMinMaxWidth(roundToInt(round(logicalHeight * intrinsicRatio)), shouldComputePreferred);
+                return computeReplacedLogicalWidthRespectingMinMaxWidth(logicalHeight * intrinsicRatio, shouldComputePreferred);
             }

[zalan]

<rdar://problem/15855716>

[Jonathan Bedard]

This is only an issue in simulators, this test passes on device.  Moved the expectation in <https://trac.webkit.org/changeset/217757/webkit>.

[Rob Buis]

Created attachment 425009 [details]
Patch