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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/175085">175085</a></dd>
<dt>Author</dt> <dd>simon.fraser@apple.com</dd>
<dt>Date</dt> <dd>2014-10-22 23:15:44 -0700 (Wed, 22 Oct 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>[iOS] Toggling overflow:scroll to hidden on element with -webkit-overflow-scrolling:touch can cause children to disappear
https://bugs.webkit.org/show_bug.cgi?id=137999
rdar://problem/18425550
Reviewed by Zalan Bujtas.
Source/WebCore:
When toggling overflow from scroll to hidden on an element with -webkit-overflow-scrolling:touch,
we'd fail to do a compositing layer rebuild, which caused various issues like unparented
descendants, and misplaced and unrepainted content.
This happened because we'd get to RenderLayerBacking::updateConfiguration() via styleChanged
with the view needing layout, so never hit the updateScrollingLayers() code, and the subsequent
updateCompositingLayers() would be a no-op.
Fix by explicitly triggering a layer rebuild when style changes such that the touch-scrollability
of an element changes, as we do for changes in clip.
Test: compositing/scrolling/touch-scroll-to-clip.html
* rendering/RenderLayerCompositor.cpp:
(WebCore::isScrollableOverflow):
(WebCore::styleHasTouchScrolling):
(WebCore::styleChangeRequiresLayerRebuild):
LayoutTests:
Test that toggles overflow on a touch scrolling div, and dumps layers.
* compositing/scrolling/touch-scroll-to-clip-expected.txt: Added.
* compositing/scrolling/touch-scroll-to-clip.html: Added.
* platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt: Added.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayerCompositorcpp">trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li>trunk/LayoutTests/compositing/scrolling/</li>
<li><a href="#trunkLayoutTestscompositingscrollingtouchscrolltoclipexpectedtxt">trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip-expected.txt</a></li>
<li><a href="#trunkLayoutTestscompositingscrollingtouchscrolltocliphtml">trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip.html</a></li>
<li>trunk/LayoutTests/platform/ios-simulator/compositing/scrolling/</li>
<li><a href="#trunkLayoutTestsplatformiossimulatorcompositingscrollingtouchscrolltoclipexpectedtxt">trunk/LayoutTests/platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (175084 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog 2014-10-23 04:32:27 UTC (rev 175084)
+++ trunk/LayoutTests/ChangeLog 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -1,3 +1,17 @@
</span><ins>+2014-10-22 Simon Fraser <simon.fraser@apple.com>
+
+ [iOS] Toggling overflow:scroll to hidden on element with -webkit-overflow-scrolling:touch can cause children to disappear
+ https://bugs.webkit.org/show_bug.cgi?id=137999
+ rdar://problem/18425550
+
+ Reviewed by Zalan Bujtas.
+
+ Test that toggles overflow on a touch scrolling div, and dumps layers.
+
+ * compositing/scrolling/touch-scroll-to-clip-expected.txt: Added.
+ * compositing/scrolling/touch-scroll-to-clip.html: Added.
+ * platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt: Added.
+
</ins><span class="cx"> 2014-10-22 Byungseon Shin <sun.shin@lge.com>
</span><span class="cx">
</span><span class="cx"> String(new Date(Mar 30 2014 01:00:00)) is wrong in CET
</span></span></pre></div>
<a id="trunkLayoutTestscompositingscrollingtouchscrolltoclipexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip-expected.txt (0 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip-expected.txt (rev 0)
+++ trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip-expected.txt 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -0,0 +1,30 @@
</span><ins>+(GraphicsLayer
+ (anchor 0.00 0.00)
+ (bounds 800.00 600.00)
+ (children 1
+ (GraphicsLayer
+ (bounds 800.00 600.00)
+ (contentsOpaque 1)
+ (children 1
+ (GraphicsLayer
+ (position 8.00 8.00)
+ (bounds 320.00 440.00)
+ (children 1
+ (GraphicsLayer
+ (position 20.00 20.00)
+ (bounds 280.00 400.00)
+ (children 1
+ (GraphicsLayer
+ (anchor 0.50 0.50)
+ (bounds 265.00 500.00)
+ (contentsOpaque 1)
+ )
+ )
+ )
+ )
+ )
+ )
+ )
+ )
+)
+
</ins></span></pre></div>
<a id="trunkLayoutTestscompositingscrollingtouchscrolltocliphtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip.html (0 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip.html (rev 0)
+++ trunk/LayoutTests/compositing/scrolling/touch-scroll-to-clip.html 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -0,0 +1,64 @@
</span><ins>+<!DOCTYPE html>
+
+<html>
+<head>
+ <meta name="viewport" content="initial-scale=1.0">
+ <style>
+ html {
+ -webkit-overflow-scrolling: touch;
+ }
+ .container {
+ position: relative;
+ z-index: 0;
+ border: 20px solid black;
+ height: 400px;
+ width: 280px;
+ overflow: scroll;
+ }
+
+ .composited {
+ -webkit-transform: translateZ(0);
+ width: 100%;
+ height: 500px;
+ background-color: silver;
+ }
+
+ .container.no-scroll {
+ overflow: hidden;
+ border: 20px solid red;
+ }
+ </style>
+ <script>
+ if (window.testRunner) {
+ testRunner.waitUntilDone();
+ testRunner.dumpAsText();
+ }
+
+ function startTest()
+ {
+ document.body.offsetWidth;
+ window.setTimeout(function() {
+ var scroller = document.getElementById('scroller');
+ scroller.classList.toggle('no-scroll');
+
+ if (window.internals)
+ document.getElementById('layer-tree').innerText = window.internals.layerTreeAsText(document);
+
+ if (window.testRunner)
+ window.testRunner.notifyDone();
+
+ }, 0);
+ }
+ window.addEventListener('load', startTest, false);
+ </script>
+</head>
+<body>
+
+ <div id="scroller" class="container">
+ <div class="composited">
+ </div>
+ </div>
+<pre id="layer-tree">Layer tree goes here</pre>
+
+</body>
+</html>
</ins></span></pre></div>
<a id="trunkLayoutTestsplatformiossimulatorcompositingscrollingtouchscrolltoclipexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt (0 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt (rev 0)
+++ trunk/LayoutTests/platform/ios-simulator/compositing/scrolling/touch-scroll-to-clip-expected.txt 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -0,0 +1,28 @@
</span><ins>+(GraphicsLayer
+ (anchor 0.00 0.00)
+ (bounds 800.00 600.00)
+ (children 1
+ (GraphicsLayer
+ (bounds 800.00 600.00)
+ (children 1
+ (GraphicsLayer
+ (position 8.00 8.00)
+ (bounds 320.00 440.00)
+ (children 1
+ (GraphicsLayer
+ (position 20.00 20.00)
+ (bounds 280.00 400.00)
+ (children 1
+ (GraphicsLayer
+ (bounds 280.00 500.00)
+ (contentsOpaque 1)
+ )
+ )
+ )
+ )
+ )
+ )
+ )
+ )
+)
+
</ins></span></pre></div>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (175084 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2014-10-23 04:32:27 UTC (rev 175084)
+++ trunk/Source/WebCore/ChangeLog 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -1,3 +1,29 @@
</span><ins>+2014-10-22 Simon Fraser <simon.fraser@apple.com>
+
+ [iOS] Toggling overflow:scroll to hidden on element with -webkit-overflow-scrolling:touch can cause children to disappear
+ https://bugs.webkit.org/show_bug.cgi?id=137999
+ rdar://problem/18425550
+
+ Reviewed by Zalan Bujtas.
+
+ When toggling overflow from scroll to hidden on an element with -webkit-overflow-scrolling:touch,
+ we'd fail to do a compositing layer rebuild, which caused various issues like unparented
+ descendants, and misplaced and unrepainted content.
+
+ This happened because we'd get to RenderLayerBacking::updateConfiguration() via styleChanged
+ with the view needing layout, so never hit the updateScrollingLayers() code, and the subsequent
+ updateCompositingLayers() would be a no-op.
+
+ Fix by explicitly triggering a layer rebuild when style changes such that the touch-scrollability
+ of an element changes, as we do for changes in clip.
+
+ Test: compositing/scrolling/touch-scroll-to-clip.html
+
+ * rendering/RenderLayerCompositor.cpp:
+ (WebCore::isScrollableOverflow):
+ (WebCore::styleHasTouchScrolling):
+ (WebCore::styleChangeRequiresLayerRebuild):
+
</ins><span class="cx"> 2014-10-22 Chris Dumez <cdumez@apple.com>
</span><span class="cx">
</span><span class="cx"> Clean up virtual functions in rendering/
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayerCompositorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp (175084 => 175085)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp 2014-10-23 04:32:27 UTC (rev 175084)
+++ trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp 2014-10-23 06:15:44 UTC (rev 175085)
</span><span class="lines">@@ -862,6 +862,18 @@
</span><span class="cx"> return false;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
+static bool isScrollableOverflow(EOverflow overflow)
+{
+ return overflow == OSCROLL || overflow == OAUTO || overflow == OOVERLAY;
+}
+
+static bool styleHasTouchScrolling(const RenderStyle& style)
+{
+ return isScrollableOverflow(style.overflowX()) && style.useTouchOverflowScrolling();
+}
+#endif
+
</ins><span class="cx"> static bool styleChangeRequiresLayerRebuild(const RenderLayer& layer, const RenderStyle& oldStyle, const RenderStyle& newStyle)
</span><span class="cx"> {
</span><span class="cx"> // Clip can affect ancestor compositing bounds, so we need recompute overlap when it changes on a non-composited layer.
</span><span class="lines">@@ -872,6 +884,11 @@
</span><span class="cx"> // When overflow changes, composited layers may need to update their ancestorClipping layers.
</span><span class="cx"> if (!layer.isComposited() && (oldStyle.overflowX() != newStyle.overflowX()) && layer.stackingContainer()->hasCompositingDescendant())
</span><span class="cx"> return true;
</span><ins>+
+#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
+ if (styleHasTouchScrolling(oldStyle) != styleHasTouchScrolling(newStyle))
+ return true;
+#endif
</ins><span class="cx">
</span><span class="cx"> // Compositing layers keep track of whether they are clipped by any of the ancestors.
</span><span class="cx"> // When the current layer's clipping behaviour changes, we need to propagate it to the descendants.
</span></span></pre>
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