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
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * 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 ViewportAnchor_h
+#define ViewportAnchor_h
+
+#include "FloatSize.h"
+#include "IntPoint.h"
+#include "IntRect.h"
+#include "LayoutRect.h"
+#include <wtf/RefCounted.h>
+
+namespace WebCore {
+class EventHandler;
+class IntSize;
+class Node;
+}
+
+namespace WebKit {
+
+// 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 {
+    WTF_MAKE_NONCOPYABLE(ViewportAnchor);
+public:
+    explicit ViewportAnchor(WebCore::EventHandler* eventHandler);
+
+    void setAnchor(const WebCore::IntRect& viewRect, const WebCore::FloatSize& anchorInViewCoords);
+
+    WebCore::IntPoint computeOrigin(const WebCore::IntSize& currentViewSize) const;
+
+private:
+    WebCore::EventHandler* m_eventHandler;
+
+    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