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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef ASH_DRAG_DROP_DRAG_DROP_TRACKER_H_
      6 #define ASH_DRAG_DROP_DRAG_DROP_TRACKER_H_
      7 
      8 #include "ash/ash_export.h"
      9 #include "base/basictypes.h"
     10 #include "base/memory/scoped_ptr.h"
     11 #include "ui/events/event.h"
     12 
     13 namespace aura {
     14 class Window;
     15 class WindowDelegate;
     16 }
     17 
     18 namespace ash {
     19 
     20 // Provides functions for handling drag events inside and outside the root
     21 // window where drag is started. This internally sets up a capture window for
     22 // tracking drag events outside the root window where drag is initiated.
     23 // ash/wm/coordinate_conversion.h is used internally and only X11 environment
     24 // is supported for now.
     25 class ASH_EXPORT DragDropTracker {
     26  public:
     27   DragDropTracker(aura::Window* context_root,
     28                   aura::WindowDelegate* delegate);
     29   ~DragDropTracker();
     30 
     31   aura::Window* capture_window() { return capture_window_.get(); }
     32 
     33   // Tells our |capture_window_| to take capture. This is not done right at
     34   // creation to give the caller a chance to perform any operations needed
     35   // before the capture is transfered.
     36   void TakeCapture();
     37 
     38   // Gets the target located at |event| in the coordinates of the active root
     39   // window.
     40   aura::Window* GetTarget(const ui::LocatedEvent& event);
     41 
     42   // Converts the locations of |event| in the coordinates of the active root
     43   // window to the ones in |target|'s coordinates.
     44   // Caller takes ownership of the returned object.
     45   ui::LocatedEvent* ConvertEvent(aura::Window* target,
     46                                  const ui::LocatedEvent& event);
     47 
     48  private:
     49   // A window for capturing drag events while dragging.
     50   scoped_ptr<aura::Window> capture_window_;
     51 
     52   DISALLOW_COPY_AND_ASSIGN(DragDropTracker);
     53 };
     54 
     55 }  // namespace ash
     56 
     57 #endif  // ASH_DRAG_DROP_DRAG_DROP_TRACKER_H_
     58