ui/base/dragdrop/drag_source_win.h

   1 // Copyright (c) 2011 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 UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_
   6 #define UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_
   7
   8 #include <objidl.h>
   9
  10 #include "base/basictypes.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "ui/base/ui_base_export.h"
  13
  14 namespace ui {
  15
  16 // A base IDropSource implementation. Handles notifications sent by an active
  17 // drag-drop operation as the user mouses over other drop targets on their
  18 // system. This object tells Windows whether or not the drag should continue,
  19 // and supplies the appropriate cursors.
  20 class UI_BASE_EXPORT DragSourceWin
  21     : public IDropSource,
  22       public base::RefCountedThreadSafe<DragSourceWin> {
  23  public:
  24   DragSourceWin();
  25   virtual ~DragSourceWin() {}
  26
  27   // Stop the drag operation at the next chance we get.  This doesn't
  28   // synchronously stop the drag (since Windows is controlling that),
  29   // but lets us tell Windows to cancel the drag the next chance we get.
  30   void CancelDrag() {
  31     cancel_drag_ = true;
  32   }
  33
  34   // IDropSource implementation:
  35   HRESULT __stdcall QueryContinueDrag(BOOL escape_pressed, DWORD key_state);
  36   HRESULT __stdcall GiveFeedback(DWORD effect);
  37
  38   // IUnknown implementation:
  39   HRESULT __stdcall QueryInterface(const IID& iid, void** object);
  40   ULONG __stdcall AddRef();
  41   ULONG __stdcall Release();
  42
  43  protected:
  44   virtual void OnDragSourceCancel() {}
  45   virtual void OnDragSourceDrop() {}
  46   virtual void OnDragSourceMove() {}
  47
  48  private:
  49   // Set to true if we want to cancel the drag operation.
  50   bool cancel_drag_;
  51
  52   DISALLOW_COPY_AND_ASSIGN(DragSourceWin);
  53 };
  54
  55 }  // namespace ui
  56
  57 #endif  // UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_