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      1 /*
      2  * Copyright (C) 2013 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef ViewportAnchor_h
     32 #define ViewportAnchor_h
     33 
     34 #include "platform/geometry/FloatSize.h"
     35 #include "platform/geometry/IntPoint.h"
     36 #include "platform/geometry/IntRect.h"
     37 #include "platform/geometry/LayoutRect.h"
     38 #include "wtf/RefCounted.h"
     39 
     40 namespace WebCore {
     41 class EventHandler;
     42 class IntSize;
     43 class Node;
     44 }
     45 
     46 namespace blink {
     47 
     48 // ViewportAnchor provides a way to anchor a viewport origin to a DOM node.
     49 // In particular, the user supplies the current viewport (in CSS coordinates)
     50 // and an anchor point (in view coordinates, e.g., (0, 0) == viewport origin,
     51 // (0.5, 0) == viewport top center). The anchor point tracks the underlying DOM
     52 // node; as the node moves or the view is resized, the viewport anchor maintains
     53 // its orientation relative to the node, and the viewport origin maintains its
     54 // orientation relative to the anchor.
     55 class ViewportAnchor {
     56     WTF_MAKE_NONCOPYABLE(ViewportAnchor);
     57 public:
     58     explicit ViewportAnchor(WebCore::EventHandler* eventHandler);
     59 
     60     void setAnchor(const WebCore::IntRect& viewRect, const WebCore::FloatSize& anchorInViewCoords);
     61 
     62     WebCore::IntPoint computeOrigin(const WebCore::IntSize& currentViewSize) const;
     63 
     64 private:
     65     WebCore::EventHandler* m_eventHandler;
     66 
     67     WebCore::IntRect m_viewRect;
     68 
     69     RefPtr<WebCore::Node> m_anchorNode;
     70     WebCore::LayoutRect m_anchorNodeBounds;
     71 
     72     WebCore::FloatSize m_anchorInViewCoords;
     73     WebCore::FloatSize m_anchorInNodeCoords;
     74 };
     75 
     76 } // namespace blink
     77 
     78  #endif
     79