Disable touch highlight when the touched node has no hand-cursor.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1148 matching lines @@
     else
         rect.x = std::max<float>(rect.x, hitPoint.x + padding - screenWidth);
     scroll.x = rect.x;
     scroll.y = rect.y;
 
     scale = clampPageScaleFactorToLimits(scale);
     scroll = mainFrameImpl()->frameView()->windowToContents(scroll);
     scroll = clampOffsetAtScale(scroll, scale);
 }
 
-static bool invokesHandCursor(Node* node, LocalFrame* frame)
+static Node* findCursorDefiningAncestor(Node* node, LocalFrame* frame)
+{
+    // Go up the tree to find the node that defines a mouse cursor style
+    while (node) {
+        if (node->renderer()) {
+            ECursor cursor = node->renderer()->style()->cursor();
+            if (cursor != CURSOR_AUTO || frame->eventHandler().useHandCursor(node, node->isLink()))
+                break;
+        }
+        node = node->parentNode();

[Rick Byers, 2014/08/15 18:03:12]

Note that you lost the NodeRenderingTraversal::parentNode() fix we discussed
here.  It just came up in this review:
https://codereview.chromium.org/470803002/diff/1/Source/web/WebViewImpl.cpp.

[mustaq, 2014/08/18 14:01:00]

Ooops, seems I accidentally reverted the suggestion while stepping back in the
CL. I'll fix this now.

+    }
+
+    return node;
+}
+
+static bool showsHandCursor(Node* node, LocalFrame* frame)
 {
     if (!node || !node->renderer())
         return false;
 
     ECursor cursor = node->renderer()->style()->cursor();
     return cursor == CURSOR_POINTER
         || (cursor == CURSOR_AUTO && frame->eventHandler().useHandCursor(node, node->isLink()));
 }
 
 Node* WebViewImpl::bestTapNode(const PlatformGestureEvent& tapEvent)
 {
     TRACE_EVENT0("input", "WebViewImpl::bestTapNode");
 
     if (!m_page || !m_page->mainFrame())
         return 0;
 
-    Node* bestTouchNode = 0;
-
     // FIXME: Rely on earlier hit test instead of hit testing again.
-    GestureEventWithHitTestResults targetedEvent = m_page->deprecatedLocalMainFrame()->eventHandler().targetGestureEvent(tapEvent, true);
-    bestTouchNode = targetedEvent.hitTestResult().targetNode();
+    GestureEventWithHitTestResults targetedEvent =
+        m_page->deprecatedLocalMainFrame()->eventHandler().targetGestureEvent(tapEvent, true);
+    Node* bestTouchNode = targetedEvent.hitTestResult().targetNode();
 
     // We might hit something like an image map that has no renderer on it
     // Walk up the tree until we have a node with an attached renderer
     while (bestTouchNode && !bestTouchNode->renderer())
         bestTouchNode = bestTouchNode->parentNode();
 
-    // Check if we're in the subtree of a node with a hand cursor
-    // this is the heuristic we use to determine if we show a highlight on tap
-    while (bestTouchNode && !invokesHandCursor(bestTouchNode, m_page->deprecatedLocalMainFrame()))
-        bestTouchNode = bestTouchNode->parentNode();
+    Node* cursorDefiningAncestor =
+        findCursorDefiningAncestor(bestTouchNode, m_page->deprecatedLocalMainFrame());
+    // We show a highlight on tap only when the current node shows a hand cursor
+    if (!cursorDefiningAncestor || !showsHandCursor(cursorDefiningAncestor, m_page->deprecatedLocalMainFrame())) {
+        return 0;
+    }
 
-    if (!bestTouchNode)
-        return 0;
-
-    // We should pick the largest enclosing node with hand cursor set.
-    while (bestTouchNode->parentNode() && invokesHandCursor(bestTouchNode->parentNode(), toLocalFrame(m_page->mainFrame())))
-        bestTouchNode = bestTouchNode->parentNode();
+    // We should pick the largest enclosing node with hand cursor set. We do this by first jumping
+    // up to cursorDefiningAncestor (which is already known to have hand cursor set). Then we locate
+    // the next cursor-defining ancestor up in the the tree and repeat the jumps as long as the node
+    // has hand cursor set.
+    do {
+        bestTouchNode = cursorDefiningAncestor;
+        cursorDefiningAncestor = findCursorDefiningAncestor(bestTouchNode->parentNode(), m_page->deprecatedLocalMainFrame());
+    } while (cursorDefiningAncestor && showsHandCursor(cursorDefiningAncestor, m_page->deprecatedLocalMainFrame()));
 
     return bestTouchNode;
 }
 
 void WebViewImpl::enableTapHighlightAtPoint(const PlatformGestureEvent& tapEvent)
 {
     Node* touchNode = bestTapNode(tapEvent);
 
     WillBeHeapVector<RawPtrWillBeMember<Node> > highlightNodes;
     highlightNodes.append(touchNode);
@@ skipping 3031 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink