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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/214816">214816</a></dd>
<dt>Author</dt> <dd>carlosgc@webkit.org</dd>
<dt>Date</dt> <dd>2017-04-03 10:32:26 -0700 (Mon, 03 Apr 2017)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/214726">r214726</a> - Long Arabic text in ContentEditable with css white-space=pre hangs Safari
https://bugs.webkit.org/show_bug.cgi?id=170245
Reviewed by Myles C. Maxfield.
While searching for mid-word break, we measure the text by codepoints in a loop until the accumulated width > available width.
When we see that the accumulated width for the individual codepoints overflows, we join the codepoints and re-measure them.
These 2 widths could be considerably different for number of reasons (ligatures is a prime example). When we figure that
the run still fits, we go back to the main loop (since we are not supposed to wrap the line here) and take the next codepoint.
However this time we start the measurement from the last whitespace, so we end up remeasuring a potentially long chuck of text
until we hit the wrapping point. This is way too expensive.
This patch changes the logic so that we just go back to measuring individual codepoints until we hit the constrain again.
Covered by existing tests.
* rendering/line/BreakingContext.h:
(WebCore::BreakingContext::handleText): canUseSimpleFontCodePath() is just to mitigate the potential risk of regression and
complex text is more likely to fall into this category.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#releasesWebKitGTKwebkit216SourceWebCoreChangeLog">releases/WebKitGTK/webkit-2.16/Source/WebCore/ChangeLog</a></li>
<li><a href="#releasesWebKitGTKwebkit216SourceWebCorerenderinglineBreakingContexth">releases/WebKitGTK/webkit-2.16/Source/WebCore/rendering/line/BreakingContext.h</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="releasesWebKitGTKwebkit216SourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.16/Source/WebCore/ChangeLog (214815 => 214816)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.16/Source/WebCore/ChangeLog 2017-04-03 17:29:09 UTC (rev 214815)
+++ releases/WebKitGTK/webkit-2.16/Source/WebCore/ChangeLog 2017-04-03 17:32:26 UTC (rev 214816)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2017-04-01 Zalan Bujtas <zalan@apple.com>
+
+ Long Arabic text in ContentEditable with css white-space=pre hangs Safari
+ https://bugs.webkit.org/show_bug.cgi?id=170245
+
+ Reviewed by Myles C. Maxfield.
+
+ While searching for mid-word break, we measure the text by codepoints in a loop until the accumulated width > available width.
+ When we see that the accumulated width for the individual codepoints overflows, we join the codepoints and re-measure them.
+ These 2 widths could be considerably different for number of reasons (ligatures is a prime example). When we figure that
+ the run still fits, we go back to the main loop (since we are not supposed to wrap the line here) and take the next codepoint.
+ However this time we start the measurement from the last whitespace, so we end up remeasuring a potentially long chuck of text
+ until we hit the wrapping point. This is way too expensive.
+ This patch changes the logic so that we just go back to measuring individual codepoints until we hit the constrain again.
+
+ Covered by existing tests.
+
+ * rendering/line/BreakingContext.h:
+ (WebCore::BreakingContext::handleText): canUseSimpleFontCodePath() is just to mitigate the potential risk of regression and
+ complex text is more likely to fall into this category.
+
</ins><span class="cx"> 2017-03-30 Eric Carlson <eric.carlson@apple.com>
</span><span class="cx">
</span><span class="cx"> [Crash] WebCore::AudioBuffer::AudioBuffer don't checking illegal value
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit216SourceWebCorerenderinglineBreakingContexth"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.16/Source/WebCore/rendering/line/BreakingContext.h (214815 => 214816)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.16/Source/WebCore/rendering/line/BreakingContext.h 2017-04-03 17:29:09 UTC (rev 214815)
+++ releases/WebKitGTK/webkit-2.16/Source/WebCore/rendering/line/BreakingContext.h 2017-04-03 17:32:26 UTC (rev 214816)
</span><span class="lines">@@ -794,7 +794,8 @@
</span><span class="cx"> float lastSpaceWordSpacing = 0;
</span><span class="cx"> float wordSpacingForWordMeasurement = 0;
</span><span class="cx">
</span><del>- float wrapW = m_width.uncommittedWidth() + inlineLogicalWidth(m_current.renderer(), !m_appliedStartWidth, true);
</del><ins>+ float wrapWidthOffset = m_width.uncommittedWidth() + inlineLogicalWidth(m_current.renderer(), !m_appliedStartWidth, true);
+ float wrapW = wrapWidthOffset;
</ins><span class="cx"> float charWidth = 0;
</span><span class="cx"> bool breakNBSP = m_autoWrap && m_currentStyle->nbspMode() == SPACE;
</span><span class="cx"> // Auto-wrapping text should wrap in the middle of a word only if it could not wrap before the word,
</span><span class="lines">@@ -1028,7 +1029,8 @@
</span><span class="cx">
</span><span class="cx"> if (m_autoWrap && betweenWords) {
</span><span class="cx"> commitLineBreakAtCurrentWidth(renderObject, m_current.offset(), m_current.nextBreakablePosition());
</span><del>- wrapW = 0;
</del><ins>+ wrapWidthOffset = 0;
+ wrapW = wrapWidthOffset;
</ins><span class="cx"> // Auto-wrapping text should not wrap in the middle of a word once it has had an
</span><span class="cx"> // opportunity to break after a word.
</span><span class="cx"> breakWords = false;
</span><span class="lines">@@ -1060,7 +1062,12 @@
</span><span class="cx"> m_trailingObjects.updateWhitespaceCollapsingTransitionsForTrailingBoxes(m_lineWhitespaceCollapsingState, InlineIterator(), TrailingObjects::DoNotCollapseFirstSpace);
</span><span class="cx"> }
</span><span class="cx"> }
</span><del>-
</del><ins>+ // Measuring the width of complex text character-by-character, rather than measuring it all together,
+ // could produce considerably different width values.
+ if (!renderText.canUseSimpleFontCodePath() && midWordBreak && m_width.fitsOnLine()) {
+ midWordBreak = false;
+ wrapW = wrapWidthOffset + additionalTempWidth;
+ }
</ins><span class="cx"> isLineEmpty = m_lineInfo.isEmpty();
</span><span class="cx"> } else {
</span><span class="cx"> if (m_ignoringSpaces) {
</span></span></pre>
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