Add touchpad pinch zoom support to Blink

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 2122 matching lines @@
             eventType, static_cast<const WebMouseEvent&>(inputEvent).clickCount);
         return true;
     }
 
     // FIXME: This should take in the intended frame, not the local frame root.
     if (PageWidgetDelegate::handleInputEvent(*this, inputEvent, localFrameRootTemporary()->frame()))
         return true;
 
     // Unhandled touchpad gesture pinch events synthesize mouse wheel events.
     if (inputEvent.type == WebInputEvent::GesturePinchUpdate) {
-        if (handleSyntheticWheelFromTouchpadPinchEvent(static_cast<const WebGestureEvent&>(inputEvent)))
+        const WebGestureEvent& pinchEvent = static_cast<const WebGestureEvent&>(inputEvent);
+
+        // First, synthesize a Windows-like wheel event to send to any handlers that may exist.
+        if (handleSyntheticWheelFromTouchpadPinchEvent(pinchEvent))
             return true;
+
+        if (pinchVirtualViewportEnabled()) {
+            const float oldPageScale = pageScaleFactor();
+            const float newPageScale = clampPageScaleFactorToLimits(oldPageScale * pinchEvent.data.pinchUpdate.scale);
+            if (newPageScale != oldPageScale) {

[bokan, 2015/02/03 03:05:16]

Please fold this "changed" check inside the method.

[ccameron, 2015/02/03 17:03:28]

Done.

+                page()->frameHost().pinchViewport().setScaleAroundAnchor(
+                    newPageScale, FloatPoint(pinchEvent.x, pinchEvent.y));
+            }
+        }
+
+        // TODO(ccameron): Always return that the event was handled. Once the pinch-zoom content scale
+        // handlers have been removed from content, this function may return false if the page scale does
+        // not change.
+        return true;
     }
 
     return false;
 }
 
 void WebViewImpl::setCursorVisibilityState(bool isVisible)
 {
     if (m_page)
         m_page->setIsCursorVisible(isVisible);
 }
@@ skipping 2451 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink