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<div id="msg">
<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/180539">180539</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2015-02-23 18:07:33 -0800 (Mon, 23 Feb 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>[iOS WK2] The WebProcess keep scrolling pages based on the last velocity after scrolling has been interrupted
https://bugs.webkit.org/show_bug.cgi?id=141933
rdar://problem/18746673
rdar://problem/19711490
Patch by Benjamin Poulain <bpoulain@apple.com> on 2015-02-23
Reviewed by Simon Fraser.
The bug happened like this:
1) The user scroll the page. WKContentView tracks the velocity and send
the update rect + velocity to the WebProcess.
2) The user interupts the scrolling but does not commit to either scrolling
again or cancelling the scrolling.
Since we were not notified of this state, the WebProcess still believed
the velocity is stable.
3) With any paint update, the WebProcess would account for the last velocity
and try to guess the best repaint area. This would drift endlessly out
of the view since the view is not really moving.
This patch fixes the issue by adding special handling for interrupted scrolling.
Kudos to Kurt Revis for providing us the required APIs.
* Shared/VisibleContentRectUpdateInfo.h:
(WebKit::operator==):
We can no longer filter VisibleContentRectUpdateInfo ignoring the velocity.
Typically, UIScrollView would call -scrollViewDidScroll: before being interrupted.
If we filter based on the VisibleContentRectUpdateInfo, we have two identical
states differing only by the velocity. If we filter the second update, the WebProcess
would never know the velocity should be zero.
* UIProcess/API/Cocoa/WKWebView.mm:
(-[WKWebView _scrollViewDidInterruptDecelerating:]):
We get this callback when scrolling is interrupted. We just need to clear
the velocity and re-send a new update for the current state.
(-[WKWebView _updateVisibleContentRects]):
Do not consider an interrupted scroll as a stable state. We don't know if scrolling
will resume or will stop.
* UIProcess/ios/WKContentView.h:
* UIProcess/ios/WKContentView.mm:
(-[WKContentView didInterruptScrolling]):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebKit2ChangeLog">trunk/Source/WebKit2/ChangeLog</a></li>
<li><a href="#trunkSourceWebKit2SharedVisibleContentRectUpdateInfoh">trunk/Source/WebKit2/Shared/VisibleContentRectUpdateInfo.h</a></li>
<li><a href="#trunkSourceWebKit2UIProcessAPICocoaWKWebViewmm">trunk/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm</a></li>
<li><a href="#trunkSourceWebKit2UIProcessiosWKContentViewh">trunk/Source/WebKit2/UIProcess/ios/WKContentView.h</a></li>
<li><a href="#trunkSourceWebKit2UIProcessiosWKContentViewmm">trunk/Source/WebKit2/UIProcess/ios/WKContentView.mm</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebKit2ChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/ChangeLog (180538 => 180539)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/ChangeLog 2015-02-24 01:43:36 UTC (rev 180538)
+++ trunk/Source/WebKit2/ChangeLog 2015-02-24 02:07:33 UTC (rev 180539)
</span><span class="lines">@@ -1,3 +1,49 @@
</span><ins>+2015-02-23 Benjamin Poulain <bpoulain@apple.com>
+
+ [iOS WK2] The WebProcess keep scrolling pages based on the last velocity after scrolling has been interrupted
+ https://bugs.webkit.org/show_bug.cgi?id=141933
+ rdar://problem/18746673
+ rdar://problem/19711490
+
+ Reviewed by Simon Fraser.
+
+ The bug happened like this:
+ 1) The user scroll the page. WKContentView tracks the velocity and send
+ the update rect + velocity to the WebProcess.
+ 2) The user interupts the scrolling but does not commit to either scrolling
+ again or cancelling the scrolling.
+ Since we were not notified of this state, the WebProcess still believed
+ the velocity is stable.
+ 3) With any paint update, the WebProcess would account for the last velocity
+ and try to guess the best repaint area. This would drift endlessly out
+ of the view since the view is not really moving.
+
+ This patch fixes the issue by adding special handling for interrupted scrolling.
+
+ Kudos to Kurt Revis for providing us the required APIs.
+
+ * Shared/VisibleContentRectUpdateInfo.h:
+ (WebKit::operator==):
+ We can no longer filter VisibleContentRectUpdateInfo ignoring the velocity.
+
+ Typically, UIScrollView would call -scrollViewDidScroll: before being interrupted.
+ If we filter based on the VisibleContentRectUpdateInfo, we have two identical
+ states differing only by the velocity. If we filter the second update, the WebProcess
+ would never know the velocity should be zero.
+
+ * UIProcess/API/Cocoa/WKWebView.mm:
+ (-[WKWebView _scrollViewDidInterruptDecelerating:]):
+ We get this callback when scrolling is interrupted. We just need to clear
+ the velocity and re-send a new update for the current state.
+
+ (-[WKWebView _updateVisibleContentRects]):
+ Do not consider an interrupted scroll as a stable state. We don't know if scrolling
+ will resume or will stop.
+
+ * UIProcess/ios/WKContentView.h:
+ * UIProcess/ios/WKContentView.mm:
+ (-[WKContentView didInterruptScrolling]):
+
</ins><span class="cx"> 2015-02-23 Anders Carlsson <andersca@apple.com>
</span><span class="cx">
</span><span class="cx"> Add API for fetching website data records to _WKWebsiteDataStore
</span></span></pre></div>
<a id="trunkSourceWebKit2SharedVisibleContentRectUpdateInfoh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/Shared/VisibleContentRectUpdateInfo.h (180538 => 180539)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/Shared/VisibleContentRectUpdateInfo.h 2015-02-24 01:43:36 UTC (rev 180538)
+++ trunk/Source/WebKit2/Shared/VisibleContentRectUpdateInfo.h 2015-02-24 02:07:33 UTC (rev 180539)
</span><span class="lines">@@ -101,6 +101,9 @@
</span><span class="cx"> && a.exposedRect() == b.exposedRect()
</span><span class="cx"> && a.unobscuredRect() == b.unobscuredRect()
</span><span class="cx"> && a.customFixedPositionRect() == b.customFixedPositionRect()
</span><ins>+ && a.horizontalVelocity() == b.horizontalVelocity()
+ && a.verticalVelocity() == b.verticalVelocity()
+ && a.scaleChangeRate() == b.scaleChangeRate()
</ins><span class="cx"> && a.inStableState() == b.inStableState();
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessAPICocoaWKWebViewmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm (180538 => 180539)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm 2015-02-24 01:43:36 UTC (rev 180538)
+++ trunk/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm 2015-02-24 02:07:33 UTC (rev 180539)
</span><span class="lines">@@ -103,6 +103,7 @@
</span><span class="cx"> @interface UIScrollView (UIScrollViewInternal)
</span><span class="cx"> - (void)_adjustForAutomaticKeyboardInfo:(NSDictionary*)info animated:(BOOL)animated lastAdjustment:(CGFloat*)lastAdjustment;
</span><span class="cx"> - (BOOL)_isScrollingToTop;
</span><ins>+- (BOOL)_isInterruptingDeceleration;
</ins><span class="cx"> @end
</span><span class="cx">
</span><span class="cx"> @interface UIPeripheralHost(UIKitInternal)
</span><span class="lines">@@ -1411,6 +1412,15 @@
</span><span class="cx"> [self _didFinishScrolling];
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+- (void)_scrollViewDidInterruptDecelerating:(UIScrollView *)scrollView
+{
+ if (![self usesStandardContentView])
+ return;
+
+ [_contentView didInterruptScrolling];
+ [self _updateVisibleContentRects];
+}
+
</ins><span class="cx"> - (void)_frameOrBoundsChanged
</span><span class="cx"> {
</span><span class="cx"> CGRect bounds = self.bounds;
</span><span class="lines">@@ -1466,6 +1476,11 @@
</span><span class="cx"> CGFloat scaleFactor = contentZoomScale(self);
</span><span class="cx">
</span><span class="cx"> BOOL isStableState = !(_isChangingObscuredInsetsInteractively || [_scrollView isDragging] || [_scrollView isDecelerating] || [_scrollView isZooming] || [_scrollView isZoomBouncing] || [_scrollView _isAnimatingZoom] || [_scrollView _isScrollingToTop]);
</span><ins>+
+ // FIXME: this can be made static after we stop supporting iOS 8.x.
+ if (isStableState && [_scrollView respondsToSelector:@selector(_isInterruptingDeceleration)])
+ isStableState = ![_scrollView performSelector:@selector(_isInterruptingDeceleration)];
+
</ins><span class="cx"> [_contentView didUpdateVisibleRect:visibleRectInContentCoordinates
</span><span class="cx"> unobscuredRect:unobscuredRectInContentCoordinates
</span><span class="cx"> unobscuredRectInScrollViewCoordinates:unobscuredRect
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessiosWKContentViewh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/ios/WKContentView.h (180538 => 180539)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/ios/WKContentView.h 2015-02-24 01:43:36 UTC (rev 180538)
+++ trunk/Source/WebKit2/UIProcess/ios/WKContentView.h 2015-02-24 02:07:33 UTC (rev 180539)
</span><span class="lines">@@ -71,6 +71,7 @@
</span><span class="cx"> inStableState:(BOOL)isStableState isChangingObscuredInsetsInteractively:(BOOL)isChangingObscuredInsetsInteractively;
</span><span class="cx">
</span><span class="cx"> - (void)didFinishScrolling;
</span><ins>+- (void)didInterruptScrolling;
</ins><span class="cx"> - (void)didZoomToScale:(CGFloat)scale;
</span><span class="cx"> - (void)willStartZoomOrScroll;
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessiosWKContentViewmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/ios/WKContentView.mm (180538 => 180539)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/ios/WKContentView.mm 2015-02-24 01:43:36 UTC (rev 180538)
+++ trunk/Source/WebKit2/UIProcess/ios/WKContentView.mm 2015-02-24 02:07:33 UTC (rev 180539)
</span><span class="lines">@@ -381,6 +381,11 @@
</span><span class="cx"> [self _didEndScrollingOrZooming];
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+- (void)didInterruptScrolling
+{
+ _historicalKinematicData.clear();
+}
+
</ins><span class="cx"> - (void)willStartZoomOrScroll
</span><span class="cx"> {
</span><span class="cx"> [self _willStartScrollingOrZooming];
</span></span></pre>
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