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 #include <wrl/implements.h>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "ui/base/ui_base_export.h"
  14
  15 namespace ui {
  16
  17 class OSExchangeData;
  18
  19 // A base IDropSource implementation. Handles notifications sent by an active
  20 // drag-drop operation as the user mouses over other drop targets on their
  21 // system. This object tells Windows whether or not the drag should continue,
  22 // and supplies the appropriate cursors.
  23 class UI_BASE_EXPORT DragSourceWin
  24     : public Microsoft::WRL::RuntimeClass<
  25           Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>,
  26           IDropSource> {
  27  public:
  28   DragSourceWin();
  29   ~DragSourceWin() override {}
  30
  31   // Stop the drag operation at the next chance we get.  This doesn't
  32   // synchronously stop the drag (since Windows is controlling that),
  33   // but lets us tell Windows to cancel the drag the next chance we get.
  34   void CancelDrag() {
  35     cancel_drag_ = true;
  36   }
  37
  38   // IDropSource implementation:
  39   HRESULT __stdcall QueryContinueDrag(BOOL escape_pressed,
  40                                       DWORD key_state) override;
  41   HRESULT __stdcall GiveFeedback(DWORD effect) override;
  42
  43   // Used to set the active data object for the current drag operation. The
  44   // caller must ensure that |data| is not destroyed before the nested drag loop
  45   // terminates.
  46   void set_data(const OSExchangeData* data) { data_ = data; }
  47
  48  protected:
  49   virtual void OnDragSourceCancel() {}
  50   virtual void OnDragSourceDrop();
  51   virtual void OnDragSourceMove() {}
  52
  53  private:
  54   // Set to true if we want to cancel the drag operation.
  55   bool cancel_drag_;
  56
  57   const OSExchangeData* data_;
  58
  59   DISALLOW_COPY_AND_ASSIGN(DragSourceWin);
  60 };
  61
  62 }  // namespace ui
  63
  64 #endif  // UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_