Changeset 244277 in webkit

Timestamp:

Apr 15, 2019 11:56:52 AM (5 years ago)

Author:

Chris Dumez

Message:

Regression(r237903) Speedometer 2 is 1-2% regressed on iOS
​https://bugs.webkit.org/show_bug.cgi?id=196841
<rdar://problem/45957016>

Reviewed by Myles C. Maxfield.

Speedometer 2 content does not use the text-underline-offset and text-decoration-thickness
features that were added in r237903 so I looked for behavior changes in the context of
Speedometer from r237903. I found that RenderStyle::changeAffectsVisualOverflow() started
returning true a lot more often after r237903. The reason is that r237903 dropped the
visualOverflowForDecorations() checks in this method and started returning true a lot
more as a result.

To restore previous behavior, this patch adds back the visualOverflowForDecorations() checks
that were dropped in r237903. I have verified that with this patch,
RenderStyle::changeAffectsVisualOverflow() returns true as many times as it used to before
r237903.

• rendering/style/RenderStyle.cpp:

(WebCore::RenderStyle::changeAffectsVisualOverflow const):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• rendering/style/RenderStyle.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-04-15  Chris Dumez  <cdumez@apple.com>
+
+        Regression(r237903) Speedometer 2 is 1-2% regressed on iOS
+        https://bugs.webkit.org/show_bug.cgi?id=196841
+        <rdar://problem/45957016>
+
+        Reviewed by Myles C. Maxfield.
+
+        Speedometer 2 content does not use the text-underline-offset and text-decoration-thickness
+        features that were added in r237903 so I looked for behavior changes in the context of
+        Speedometer from r237903. I found that RenderStyle::changeAffectsVisualOverflow() started
+        returning true a lot more often after r237903. The reason is that r237903 dropped the
+        visualOverflowForDecorations() checks in this method and started returning true a lot
+        more as a result.
+
+        To restore previous behavior, this patch adds back the visualOverflowForDecorations() checks
+        that were dropped in r237903. I have verified that with this patch,
+        RenderStyle::changeAffectsVisualOverflow() returns true as many times as it used to before
+        r237903.
+
+        * rendering/style/RenderStyle.cpp:
+        (WebCore::RenderStyle::changeAffectsVisualOverflow const):
+
 2019-04-15  Said Abou-Hallawa  <said@apple.com>
 

trunk/Source/WebCore/rendering/style/RenderStyle.cpp

@@ -543 +543 @@
         || m_rareInheritedData->textUnderlineOffset != other.m_rareInheritedData->textUnderlineOffset
         || m_rareInheritedData->textUnderlinePosition != other.m_rareInheritedData->textUnderlinePosition) {
-        return true;
+        // Underlines are always drawn outside of their textbox bounds when text-underline-position: under;
+        // is specified. We can take an early out here.
+        if (textUnderlinePosition() == TextUnderlinePosition::Under || other.textUnderlinePosition() == TextUnderlinePosition::Under)
+            return true;
+        return visualOverflowForDecorations(*this, nullptr) != visualOverflowForDecorations(other, nullptr);
     }