Improve mobile device rotation behavior.

Source/WebKit/chromium/src/ViewportAnchor.h

 /*
  * Copyright (C) 2013 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 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebUserGestureToken_h
-#define WebUserGestureToken_h
+#ifndef ViewportAnchor_h
+#define ViewportAnchor_h
 
-#include "../../../Platform/chromium/public/WebPrivatePtr.h"
+#include "FloatSize.h"
+#include "IntPoint.h"
+#include "IntRect.h"
+#include "LayoutRect.h"
+#include <wtf/RefCounted.h>
 
 namespace WebCore {
-class UserGestureToken;
+class EventHandler;
+class IntSize;
+class Node;
 }
 
 namespace WebKit {
 
-// A WebUserGestureToken allows for storing the user gesture state of the
-// currently active context and reinstantiating it later on to continue
-// processing the user gesture in case it was not consumed meanwhile.
-class WebUserGestureToken {
+// ViewportAnchor provides a way to anchor a viewport origin to a DOM node.
+// In particular, the user supplies the current viewport (in CSS coordinates)
+// and an anchor point (in view coordinates, e.g., (0, 0) == viewport origin,
+// (0.5, 0) == viewport top center). The anchor point tracks the underlying DOM
+// node; as the node moves or the view is resized, the viewport anchor maintains
+// its orientation relative to the node, and the viewport origin maintains its
+// orientation relative to the anchor.
+#if ENABLE(VIEWPORT)
+class ViewportAnchor {

[abarth-chromium, 2013/04/18 05:33:04]

This object seems to deal entirely in terms of WebCore types.  Should it be in
Core instead?

[jdduke (slow), 2013/04/18 16:20:07]

That's hard for me to say.  This was originally intended as an internal utility
class to be used only during resize operations in WebViewImpl, which is why I'd
prefer it live as close to that class as possible.  Technically, there's likely
no reason it couldn't exist in some folder within core.  

+    WTF_MAKE_NONCOPYABLE(ViewportAnchor);
 public:
-    WebUserGestureToken() { }
-    WebUserGestureToken(const WebUserGestureToken& other) { assign(other); }
-    WebUserGestureToken& operator=(const WebUserGestureToken& other)
-    {
-        assign(other);
-        return *this;
-    }
-    ~WebUserGestureToken() { reset(); }
+    explicit ViewportAnchor(WebCore::EventHandler* eventHandler);
 
-    WEBKIT_EXPORT bool hasGestures() const;
-    bool isNull() const { return m_token.isNull(); }
+    void setAnchor(const WebCore::IntRect& viewRect, const WebCore::FloatSize& anchorInViewCoords);
 
-#if WEBKIT_IMPLEMENTATION
-    explicit WebUserGestureToken(PassRefPtr<WebCore::UserGestureToken>);
-    operator PassRefPtr<WebCore::UserGestureToken>() const;
-#endif
+    WebCore::IntPoint computeOrigin(const WebCore::IntSize& currentViewSize) const;
 
 private:
-    WEBKIT_EXPORT void assign(const WebUserGestureToken&);
-    WEBKIT_EXPORT void reset();
+    WebCore::EventHandler* m_eventHandler;
 
-    WebPrivatePtr<WebCore::UserGestureToken> m_token;
+    WebCore::IntRect m_viewRect;
+
+    RefPtr<WebCore::Node> m_anchorNode;
+    WebCore::LayoutRect m_anchorNodeBounds;
+
+    WebCore::FloatSize m_anchorInViewCoords;
+    WebCore::FloatSize m_anchorInNodeCoords;
 };
+#endif // ENABLE(VIEWPORT)
 
 } // namespace WebKit
 
-#endif // WebUserGestureToken_h
+ #endif