Changeset 201907 in webkit

Timestamp:

Jun 9, 2016 10:27:11 PM (8 years ago)

Author:

Alan Bujtas

Message:

Hairline borders do not show up on 3x displays.
​https://bugs.webkit.org/show_bug.cgi?id=158604
<rdar://problem/26511679>

Reviewed by Simon Fraser.

On a 3x display, when we convert a 1/3px hairline border from float
to LayoutUnit and pixel floor the result, we end up with a 0px width border.
It's because float to LayoutUnit is lossy and since the current kFixedPointDenominator % 3 != 0,
flooring LayoutUnit(1/3px) ends up being 0px. (float: 1/3 -> LayoutUnit: (1/3 - 1/kFixedPointDenominator) -> floor: 0)
This patch eliminates the (unnecessary) float -> LayoutUnit - float conversion on border width.

Source/WebCore:

Test: fast/borders/hidpi-3x-input-hairline-border.html

• rendering/BorderEdge.cpp:

(WebCore::BorderEdge::BorderEdge):

• rendering/BorderEdge.h:

LayoutTests:

• fast/borders/hidpi-3x-input-hairline-border-expected-mismatch.html: Added.
• fast/borders/hidpi-3x-input-hairline-border.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/borders/hidpi-3x-input-hairline-border-expected-mismatch.html (added)
• LayoutTests/fast/borders/hidpi-3x-input-hairline-border.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/BorderEdge.cpp (modified) (2 diffs)
• Source/WebCore/rendering/BorderEdge.h (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2016-06-09  Zalan Bujtas  <zalan@apple.com>
+
+        Hairline borders do not show up on 3x displays.
+        https://bugs.webkit.org/show_bug.cgi?id=158604
+        <rdar://problem/26511679>
+
+        Reviewed by Simon Fraser.
+
+        On a 3x display, when we convert a 1/3px hairline border from float
+        to LayoutUnit and pixel floor the result, we end up with a 0px width border.
+        It's because float to LayoutUnit is lossy and since the current kFixedPointDenominator % 3 != 0,
+        flooring LayoutUnit(1/3px) ends up being 0px. (float: 1/3 -> LayoutUnit: (1/3 - 1/kFixedPointDenominator) -> floor: 0)
+        This patch eliminates the (unnecessary) float -> LayoutUnit - float conversion on border width.   
+
+        * fast/borders/hidpi-3x-input-hairline-border-expected-mismatch.html: Added.
+        * fast/borders/hidpi-3x-input-hairline-border.html: Added.
+
 2016-06-09  Commit Queue  <commit-queue@webkit.org>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2016-06-09  Zalan Bujtas  <zalan@apple.com>
+
+        Hairline borders do not show up on 3x displays.
+        https://bugs.webkit.org/show_bug.cgi?id=158604
+        <rdar://problem/26511679>
+
+        Reviewed by Simon Fraser.
+
+        On a 3x display, when we convert a 1/3px hairline border from float
+        to LayoutUnit and pixel floor the result, we end up with a 0px width border.
+        It's because float to LayoutUnit is lossy and since the current kFixedPointDenominator % 3 != 0,
+        flooring LayoutUnit(1/3px) ends up being 0px. (float: 1/3 -> LayoutUnit: (1/3 - 1/kFixedPointDenominator) -> floor: 0)
+        This patch eliminates the (unnecessary) float -> LayoutUnit - float conversion on border width.   
+
+        Test: fast/borders/hidpi-3x-input-hairline-border.html
+
+        * rendering/BorderEdge.cpp:
+        (WebCore::BorderEdge::BorderEdge):
+        * rendering/BorderEdge.h:
+
 2016-06-09  Commit Queue  <commit-queue@webkit.org>
 

trunk/Source/WebCore/rendering/BorderEdge.cpp

@@ -34 +34 @@
 namespace WebCore {
 
-BorderEdge::BorderEdge(LayoutUnit edgeWidth, Color edgeColor, EBorderStyle edgeStyle, bool edgeIsTransparent, bool edgeIsPresent, float devicePixelRatio)
+BorderEdge::BorderEdge(float edgeWidth, Color edgeColor, EBorderStyle edgeStyle, bool edgeIsTransparent, bool edgeIsPresent, float devicePixelRatio)
     : m_width(edgeWidth)
     , m_color(edgeColor)
@@ -44 +44 @@
     if (edgeStyle == DOUBLE && edgeWidth  < borderWidthInDevicePixel(3))
         m_style = SOLID;
-    m_flooredToDevicePixelWidth = floorToDevicePixel(edgeWidth, devicePixelRatio);
+    m_flooredToDevicePixelWidth = floorf(edgeWidth * devicePixelRatio) / devicePixelRatio;
 }
 

trunk/Source/WebCore/rendering/BorderEdge.h

@@ -47 +47 @@
 
     BorderEdge() = default;
-    BorderEdge(LayoutUnit edgeWidth, Color edgeColor, EBorderStyle edgeStyle, bool edgeIsTransparent, bool edgeIsPresent, float devicePixelRatio);
+    BorderEdge(float edgeWidth, Color edgeColor, EBorderStyle edgeStyle, bool edgeIsTransparent, bool edgeIsPresent, float devicePixelRatio);
 
     static void getBorderEdgeInfo(BorderEdge edges[], const RenderStyle&, float deviceScaleFactor, bool includeLogicalLeftEdge = true, bool includeLogicalRightEdge = true);