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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/176305">176305</a></dd>
<dt>Author</dt> <dd>benjamin@webkit.org</dd>
<dt>Date</dt> <dd>2014-11-18 21:06:58 -0800 (Tue, 18 Nov 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>iOS8 new "slow tap" heuristic fires mouse compat events despite preventDefault on touchend
https://bugs.webkit.org/show_bug.cgi?id=137069
rdar://problem/18481464
Patch by Benjamin Poulain <bpoulain@apple.com> on 2014-11-18
Reviewed by Simon Fraser.
On WebKit2, we let UIWebTouchEventsGestureRecognizer and _UIWebHighlightLongPressGestureRecognizer
run concurrently. This causes a race with an incorrect behavior:
1) If UIWebTouchEventsGestureRecognizer does not cancel the native gestures on start.
2) _UIWebHighlightLongPressGestureRecognizer starts after highlightDelay.
3) When the finger leaves the screen, both gestures end.
-> If the touch end sent to JavaScript in [3] ask the priority over native events, that no longer stops
the _UIWebHighlightLongPressGestureRecognizer.
The two gesture recognizers can run in any order, there is no guarantee on which one runs first.
To solve the bug, I must make sure the _UIWebHighlightLongPressGestureRecognizer never trigger a click
if the page wants the event.
To solve the order problem, I use the fact that event recognition goes in two phases for
non cancelled events:
1) Update the gesture recognizers.
2) Trigger the actions.
I do not know the order of recognizers in [1], but I know both have run before [2] is executed.
I use that to stop _UIWebHighlightLongPressGestureRecognizer from ending with a click in the case of the bug:
1) When _UIWebHighlightLongPressGestureRecognizer starts, I set _highlightLongPressCanClick signaling
the gesture can end normally. This is done on a timer and not direct input so I don't really have to worry
about a race here.
2) When processing the touch event for UIWebTouchEventsGestureRecognizer, I reset the flag _highlightLongPressCanClick
if the page wants the event.
3) When the actions of _UIWebHighlightLongPressGestureRecognizer are processed, the touch event
has already been processed by the page and the flag has been cleared if needed.
* UIProcess/ios/WKContentViewInteraction.h:
* UIProcess/ios/WKContentViewInteraction.mm:
(-[WKContentView _webTouchEvent:preventsNativeGestures:]):
(-[WKContentView _highlightLongPressRecognized:]):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebKit2ChangeLog">trunk/Source/WebKit2/ChangeLog</a></li>
<li><a href="#trunkSourceWebKit2UIProcessiosWKContentViewInteractionh">trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.h</a></li>
<li><a href="#trunkSourceWebKit2UIProcessiosWKContentViewInteractionmm">trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.mm</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebKit2ChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/ChangeLog (176304 => 176305)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/ChangeLog 2014-11-19 04:31:51 UTC (rev 176304)
+++ trunk/Source/WebKit2/ChangeLog 2014-11-19 05:06:58 UTC (rev 176305)
</span><span class="lines">@@ -1,3 +1,43 @@
</span><ins>+2014-11-18 Benjamin Poulain <bpoulain@apple.com>
+
+ iOS8 new "slow tap" heuristic fires mouse compat events despite preventDefault on touchend
+ https://bugs.webkit.org/show_bug.cgi?id=137069
+ rdar://problem/18481464
+
+ Reviewed by Simon Fraser.
+
+ On WebKit2, we let UIWebTouchEventsGestureRecognizer and _UIWebHighlightLongPressGestureRecognizer
+ run concurrently. This causes a race with an incorrect behavior:
+ 1) If UIWebTouchEventsGestureRecognizer does not cancel the native gestures on start.
+ 2) _UIWebHighlightLongPressGestureRecognizer starts after highlightDelay.
+ 3) When the finger leaves the screen, both gestures end.
+ -> If the touch end sent to JavaScript in [3] ask the priority over native events, that no longer stops
+ the _UIWebHighlightLongPressGestureRecognizer.
+
+ The two gesture recognizers can run in any order, there is no guarantee on which one runs first.
+ To solve the bug, I must make sure the _UIWebHighlightLongPressGestureRecognizer never trigger a click
+ if the page wants the event.
+
+ To solve the order problem, I use the fact that event recognition goes in two phases for
+ non cancelled events:
+ 1) Update the gesture recognizers.
+ 2) Trigger the actions.
+
+ I do not know the order of recognizers in [1], but I know both have run before [2] is executed.
+ I use that to stop _UIWebHighlightLongPressGestureRecognizer from ending with a click in the case of the bug:
+ 1) When _UIWebHighlightLongPressGestureRecognizer starts, I set _highlightLongPressCanClick signaling
+ the gesture can end normally. This is done on a timer and not direct input so I don't really have to worry
+ about a race here.
+ 2) When processing the touch event for UIWebTouchEventsGestureRecognizer, I reset the flag _highlightLongPressCanClick
+ if the page wants the event.
+ 3) When the actions of _UIWebHighlightLongPressGestureRecognizer are processed, the touch event
+ has already been processed by the page and the flag has been cleared if needed.
+
+ * UIProcess/ios/WKContentViewInteraction.h:
+ * UIProcess/ios/WKContentViewInteraction.mm:
+ (-[WKContentView _webTouchEvent:preventsNativeGestures:]):
+ (-[WKContentView _highlightLongPressRecognized:]):
+
</ins><span class="cx"> 2014-11-18 Ryosuke Niwa <rniwa@webkit.org>
</span><span class="cx">
</span><span class="cx"> iOS build fix after r176299. This method is not defined in WKViewIOS.mm.
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessiosWKContentViewInteractionh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.h (176304 => 176305)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.h 2014-11-19 04:31:51 UTC (rev 176304)
+++ trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.h 2014-11-19 05:06:58 UTC (rev 176305)
</span><span class="lines">@@ -136,6 +136,7 @@
</span><span class="cx"> BOOL _hasValidPositionInformation;
</span><span class="cx"> BOOL _isTapHighlightIDValid;
</span><span class="cx"> BOOL _potentialTapInProgress;
</span><ins>+ BOOL _highlightLongPressCanClick;
</ins><span class="cx"> BOOL _hasTapHighlightForPotentialTap;
</span><span class="cx"> BOOL _selectionNeedsUpdate;
</span><span class="cx"> BOOL _shouldRestoreSelection;
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessiosWKContentViewInteractionmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.mm (176304 => 176305)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.mm 2014-11-19 04:31:51 UTC (rev 176304)
+++ trunk/Source/WebKit2/UIProcess/ios/WKContentViewInteraction.mm 2014-11-19 05:06:58 UTC (rev 176305)
</span><span class="lines">@@ -537,6 +537,8 @@
</span><span class="cx"> - (void)_webTouchEvent:(const WebKit::NativeWebTouchEvent&)touchEvent preventsNativeGestures:(BOOL)preventsNativeGesture
</span><span class="cx"> {
</span><span class="cx"> if (preventsNativeGesture) {
</span><ins>+ _highlightLongPressCanClick = NO;
+
</ins><span class="cx"> _canSendTouchEventsAsynchronously = YES;
</span><span class="cx"> [_touchEventGestureRecognizer setDefaultPrevented:YES];
</span><span class="cx"> }
</span><span class="lines">@@ -934,19 +936,22 @@
</span><span class="cx">
</span><span class="cx"> switch ([gestureRecognizer state]) {
</span><span class="cx"> case UIGestureRecognizerStateBegan:
</span><ins>+ _highlightLongPressCanClick = YES;
</ins><span class="cx"> cancelPotentialTapIfNecessary(self);
</span><span class="cx"> _page->tapHighlightAtPosition([gestureRecognizer startPoint], ++_latestTapHighlightID);
</span><span class="cx"> _isTapHighlightIDValid = YES;
</span><span class="cx"> break;
</span><span class="cx"> case UIGestureRecognizerStateEnded:
</span><del>- if (!_positionInformation.clickableElementName.isEmpty()) {
</del><ins>+ if (_highlightLongPressCanClick && !_positionInformation.clickableElementName.isEmpty()) {
</ins><span class="cx"> [self _attemptClickAtLocation:[gestureRecognizer startPoint]];
</span><span class="cx"> [self _finishInteraction];
</span><span class="cx"> } else
</span><span class="cx"> [self _cancelInteraction];
</span><ins>+ _highlightLongPressCanClick = NO;
</ins><span class="cx"> break;
</span><span class="cx"> case UIGestureRecognizerStateCancelled:
</span><span class="cx"> [self _cancelInteraction];
</span><ins>+ _highlightLongPressCanClick = NO;
</ins><span class="cx"> break;
</span><span class="cx"> default:
</span><span class="cx"> break;
</span></span></pre>
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