Add support for touch-action: pinch-zoom.

third_party/WebKit/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 894 matching lines @@
         NOTREACHED();
     }
     m_client->didHandleGestureEvent(event, eventCancelled);
     return eventResult;
 }
 
 WebInputEventResult WebViewImpl::handleSyntheticWheelFromTouchpadPinchEvent(const WebGestureEvent& pinchEvent)
 {
     DCHECK_EQ(pinchEvent.type, WebInputEvent::GesturePinchUpdate);
 
-    // Touchscreen pinch events should not reach Blink.
-    DCHECK_EQ(pinchEvent.sourceDevice, WebGestureDeviceTouchpad);
-
     // For pinch gesture events, match typical trackpad behavior on Windows by sending fake
     // wheel events with the ctrl modifier set when we see trackpad pinch gestures.  Ideally
     // we'd someday get a platform 'pinch' event and send that instead.
     WebMouseWheelEvent wheelEvent;
     wheelEvent.type = WebInputEvent::MouseWheel;
     wheelEvent.timeStampSeconds = pinchEvent.timeStampSeconds;
     wheelEvent.windowX = wheelEvent.x = pinchEvent.x;
     wheelEvent.windowY = wheelEvent.y = pinchEvent.y;
     wheelEvent.globalX = pinchEvent.globalX;
     wheelEvent.globalY = pinchEvent.globalY;
@@ skipping 1283 matching lines @@
             PlatformMouseEventBuilder(mainFrameImpl()->frameView(), static_cast<const WebMouseEvent&>(inputEvent)),
             eventType, static_cast<const WebMouseEvent&>(inputEvent).clickCount);
         return WebInputEventResult::HandledSystem;
     }
 
     // FIXME: This should take in the intended frame, not the local frame root.
     WebInputEventResult result = PageWidgetDelegate::handleInputEvent(*this, inputEvent, mainFrameImpl()->frame());
     if (result != WebInputEventResult::NotHandled)
         return result;
 
-    // Unhandled touchpad gesture pinch events synthesize mouse wheel events.
+    // Unhandled pinch events should adjust the scale.
     if (inputEvent.type == WebInputEvent::GesturePinchUpdate) {
         const WebGestureEvent& pinchEvent = static_cast<const WebGestureEvent&>(inputEvent);
 
-        // First, synthesize a Windows-like wheel event to send to any handlers that may exist.
-        result = handleSyntheticWheelFromTouchpadPinchEvent(pinchEvent);
-        if (result != WebInputEventResult::NotHandled)
-            return result;
+        // For touchpad gestures synthesize a Windows-like wheel event
+        // to send to any handlers that may exist. Not necessary for touchscreen
+        // as touch events would have already been sent for the gesture.
+        if (pinchEvent.sourceDevice == WebGestureDeviceTouchpad) {
+            result = handleSyntheticWheelFromTouchpadPinchEvent(pinchEvent);
+            if (result != WebInputEventResult::NotHandled)
+                return result;
+        }
 
         if (pinchEvent.data.pinchUpdate.zoomDisabled)
             return WebInputEventResult::NotHandled;
 
         if (page()->frameHost().visualViewport().magnifyScaleAroundAnchor(pinchEvent.data.pinchUpdate.scale, FloatPoint(pinchEvent.x, pinchEvent.y)))
             return WebInputEventResult::HandledSystem;
     }
 
     return WebInputEventResult::NotHandled;
 }
@@ skipping 2352 matching lines @@
         return nullptr;
     return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const
 {
     return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 } // namespace blink