<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>[170746] trunk/Source/WebCore</title>
</head>
<body>

<style type="text/css"><!--
#msg dl.meta { border: 1px #006 solid; background: #369; padding: 6px; color: #fff; }
#msg dl.meta dt { float: left; width: 6em; font-weight: bold; }
#msg dt:after { content:':';}
#msg dl, #msg dt, #msg ul, #msg li, #header, #footer, #logmsg { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt;  }
#msg dl a { font-weight: bold}
#msg dl a:link    { color:#fc3; }
#msg dl a:active  { color:#ff0; }
#msg dl a:visited { color:#cc6; }
h3 { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt; font-weight: bold; }
#msg pre { overflow: auto; background: #ffc; border: 1px #fa0 solid; padding: 6px; }
#logmsg { background: #ffc; border: 1px #fa0 solid; padding: 1em 1em 0 1em; }
#logmsg p, #logmsg pre, #logmsg blockquote { margin: 0 0 1em 0; }
#logmsg p, #logmsg li, #logmsg dt, #logmsg dd { line-height: 14pt; }
#logmsg h1, #logmsg h2, #logmsg h3, #logmsg h4, #logmsg h5, #logmsg h6 { margin: .5em 0; }
#logmsg h1:first-child, #logmsg h2:first-child, #logmsg h3:first-child, #logmsg h4:first-child, #logmsg h5:first-child, #logmsg h6:first-child { margin-top: 0; }
#logmsg ul, #logmsg ol { padding: 0; list-style-position: inside; margin: 0 0 0 1em; }
#logmsg ul { text-indent: -1em; padding-left: 1em; }#logmsg ol { text-indent: -1.5em; padding-left: 1.5em; }
#logmsg > ul, #logmsg > ol { margin: 0 0 1em 0; }
#logmsg pre { background: #eee; padding: 1em; }
#logmsg blockquote { border: 1px solid #fa0; border-left-width: 10px; padding: 1em 1em 0 1em; background: white;}
#logmsg dl { margin: 0; }
#logmsg dt { font-weight: bold; }
#logmsg dd { margin: 0; padding: 0 0 0.5em 0; }
#logmsg dd:before { content:'\00bb';}
#logmsg table { border-spacing: 0px; border-collapse: collapse; border-top: 4px solid #fa0; border-bottom: 1px solid #fa0; background: #fff; }
#logmsg table th { text-align: left; font-weight: normal; padding: 0.2em 0.5em; border-top: 1px dotted #fa0; }
#logmsg table td { text-align: right; border-top: 1px dotted #fa0; padding: 0.2em 0.5em; }
#logmsg table thead th { text-align: center; border-bottom: 1px solid #fa0; }
#logmsg table th.Corner { text-align: left; }
#logmsg hr { border: none 0; border-top: 2px dashed #fa0; height: 1px; }
#header, #footer { color: #fff; background: #636; border: 1px #300 solid; padding: 6px; }
#patch { width: 100%; }
#patch h4 {font-family: verdana,arial,helvetica,sans-serif;font-size:10pt;padding:8px;background:#369;color:#fff;margin:0;}
#patch .propset h4, #patch .binary h4 {margin:0;}
#patch pre {padding:0;line-height:1.2em;margin:0;}
#patch .diff {width:100%;background:#eee;padding: 0 0 10px 0;overflow:auto;}
#patch .propset .diff, #patch .binary .diff  {padding:10px 0;}
#patch span {display:block;padding:0 10px;}
#patch .modfile, #patch .addfile, #patch .delfile, #patch .propset, #patch .binary, #patch .copfile {border:1px solid #ccc;margin:10px 0;}
#patch ins {background:#dfd;text-decoration:none;display:block;padding:0 10px;}
#patch del {background:#fdd;text-decoration:none;display:block;padding:0 10px;}
#patch .lines, .info {color:#888;background:#fff;}
--></style>
<div id="msg">
<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/170746">170746</a></dd>
<dt>Author</dt> <dd>jhoneycutt@apple.com</dd>
<dt>Date</dt> <dd>2014-07-02 21:25:27 -0700 (Wed, 02 Jul 2014)</dd>
</dl>

<h3>Log Message</h3>
<pre>Removing an element with CSS -webkit-overflow-scrolling: touch breaks
subsequent touch events

&lt;https://bugs.webkit.org/show_bug.cgi?id=134584&gt;
&lt;rdar://problem/17202021&gt;

This issue is caused by the order of teardown for RenderLayers.

RenderLayer clears its m_backing in its destructor, calling the
RenderLayerBacking destructor. The RenderLayerBacking destructor calls
RenderLayerCompositor::willRemoveScrollingLayer(), which tries to
access the RenderLayer's backing that has already been cleared. This
causes us to skip the call to ChromeClient::removeScrollingLayer(),
resulting in a stale view that can block touch events.

Reviewed by Simon Fraser.

* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::updateScrollingLayers):
When calling willRemoveScrollingLayerWithBacking(), pass both the layer
and the RenderLayerBacking.

* rendering/RenderLayerCompositor.cpp:
(WebCore::RenderLayerCompositor::willRemoveScrollingLayerWithBacking):
Renamed. Use the passed RenderLayerBacking, as the RenderLayer's
backing might have already been cleared.
(WebCore::RenderLayerCompositor::willRemoveScrollingLayer): Deleted.

* rendering/RenderLayerCompositor.h:
Renamed willRemoveScrollingLayer() to
willRemoveScrollingLayerWithBacking() and added a parameter.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayerBackingcpp">trunk/Source/WebCore/rendering/RenderLayerBacking.cpp</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayerCompositorcpp">trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayerCompositorh">trunk/Source/WebCore/rendering/RenderLayerCompositor.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (170745 => 170746)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog        2014-07-03 04:03:32 UTC (rev 170745)
+++ trunk/Source/WebCore/ChangeLog        2014-07-03 04:25:27 UTC (rev 170746)
</span><span class="lines">@@ -1,3 +1,37 @@
</span><ins>+2014-07-02  Jon Honeycutt  &lt;jhoneycutt@apple.com&gt;
+
+        Removing an element with CSS -webkit-overflow-scrolling: touch breaks
+        subsequent touch events
+
+        &lt;https://bugs.webkit.org/show_bug.cgi?id=134584&gt;
+        &lt;rdar://problem/17202021&gt;
+
+        This issue is caused by the order of teardown for RenderLayers.
+
+        RenderLayer clears its m_backing in its destructor, calling the
+        RenderLayerBacking destructor. The RenderLayerBacking destructor calls
+        RenderLayerCompositor::willRemoveScrollingLayer(), which tries to
+        access the RenderLayer's backing that has already been cleared. This
+        causes us to skip the call to ChromeClient::removeScrollingLayer(),
+        resulting in a stale view that can block touch events.
+
+        Reviewed by Simon Fraser.
+
+        * rendering/RenderLayerBacking.cpp:
+        (WebCore::RenderLayerBacking::updateScrollingLayers):
+        When calling willRemoveScrollingLayerWithBacking(), pass both the layer
+        and the RenderLayerBacking.
+
+        * rendering/RenderLayerCompositor.cpp:
+        (WebCore::RenderLayerCompositor::willRemoveScrollingLayerWithBacking):
+        Renamed. Use the passed RenderLayerBacking, as the RenderLayer's
+        backing might have already been cleared.
+        (WebCore::RenderLayerCompositor::willRemoveScrollingLayer): Deleted.
+
+        * rendering/RenderLayerCompositor.h:
+        Renamed willRemoveScrollingLayer() to
+        willRemoveScrollingLayerWithBacking() and added a parameter.
+
</ins><span class="cx"> 2014-07-01  Mark Rowe  &lt;mrowe@apple.com&gt;
</span><span class="cx"> 
</span><span class="cx">         Ensure that the WebKit bundle version in the user agent string continues to match the current format.
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayerBackingcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayerBacking.cpp (170745 => 170746)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayerBacking.cpp        2014-07-03 04:03:32 UTC (rev 170745)
+++ trunk/Source/WebCore/rendering/RenderLayerBacking.cpp        2014-07-03 04:25:27 UTC (rev 170746)
</span><span class="lines">@@ -1429,7 +1429,7 @@
</span><span class="cx">         m_scrollingContentsLayer-&gt;setPaintingPhase(paintPhase);
</span><span class="cx">         m_scrollingLayer-&gt;addChild(m_scrollingContentsLayer.get());
</span><span class="cx">     } else {
</span><del>-        compositor().willRemoveScrollingLayer(m_owningLayer);
</del><ins>+        compositor().willRemoveScrollingLayerWithBacking(m_owningLayer, *this);
</ins><span class="cx"> 
</span><span class="cx">         willDestroyLayer(m_scrollingLayer.get());
</span><span class="cx">         willDestroyLayer(m_scrollingContentsLayer.get());
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayerCompositorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp (170745 => 170746)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp        2014-07-03 04:03:32 UTC (rev 170745)
+++ trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp        2014-07-03 04:25:27 UTC (rev 170746)
</span><span class="lines">@@ -3833,13 +3833,10 @@
</span><span class="cx"> }
</span><span class="cx"> #endif
</span><span class="cx"> 
</span><del>-void RenderLayerCompositor::willRemoveScrollingLayer(RenderLayer&amp; layer)
</del><ins>+void RenderLayerCompositor::willRemoveScrollingLayerWithBacking(RenderLayer&amp; layer, RenderLayerBacking&amp; backing)
</ins><span class="cx"> {
</span><span class="cx">     if (ScrollingCoordinator* scrollingCoordinator = this-&gt;scrollingCoordinator()) {
</span><del>-        RenderLayerBacking* backing = layer.backing();
-    
-        if (backing)
-            backing-&gt;detachFromScrollingCoordinator();
</del><ins>+        backing.detachFromScrollingCoordinator();
</ins><span class="cx"> 
</span><span class="cx">         // For Coordinated Graphics.
</span><span class="cx">         scrollingCoordinator-&gt;scrollableAreaScrollLayerDidChange(&amp;layer);
</span><span class="lines">@@ -3850,12 +3847,12 @@
</span><span class="cx">     m_scrollingLayersNeedingUpdate.remove(&amp;layer);
</span><span class="cx">     m_scrollingLayers.remove(&amp;layer);
</span><span class="cx"> 
</span><del>-    if (m_renderView.document().inPageCache() || !layer.backing())
</del><ins>+    if (m_renderView.document().inPageCache())
</ins><span class="cx">         return;
</span><span class="cx"> 
</span><span class="cx">     if (ChromeClient* client = this-&gt;chromeClient()) {
</span><del>-        PlatformLayer* scrollingLayer = layer.backing()-&gt;scrollingLayer()-&gt;platformLayer();
-        PlatformLayer* contentsLayer = layer.backing()-&gt;scrollingContentsLayer()-&gt;platformLayer();
</del><ins>+        PlatformLayer* scrollingLayer = backing.scrollingLayer()-&gt;platformLayer();
+        PlatformLayer* contentsLayer = backing.scrollingContentsLayer()-&gt;platformLayer();
</ins><span class="cx">         client-&gt;removeScrollingLayer(layer.renderer().element(), scrollingLayer, contentsLayer);
</span><span class="cx">     }
</span><span class="cx"> #endif
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayerCompositorh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayerCompositor.h (170745 => 170746)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayerCompositor.h        2014-07-03 04:03:32 UTC (rev 170745)
+++ trunk/Source/WebCore/rendering/RenderLayerCompositor.h        2014-07-03 04:25:27 UTC (rev 170746)
</span><span class="lines">@@ -275,7 +275,7 @@
</span><span class="cx">     void updateScrollCoordinatedStatus(RenderLayer&amp;);
</span><span class="cx">     void removeFromScrollCoordinatedLayers(RenderLayer&amp;);
</span><span class="cx"> 
</span><del>-    void willRemoveScrollingLayer(RenderLayer&amp;);
</del><ins>+    void willRemoveScrollingLayerWithBacking(RenderLayer&amp;, RenderLayerBacking&amp;);
</ins><span class="cx">     void didAddScrollingLayer(RenderLayer&amp;);
</span><span class="cx"> 
</span><span class="cx"> #if PLATFORM(IOS)
</span></span></pre>
</div>
</div>

</body>
</html>