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
14namespace 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.
20class 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_
58