1 // Copyright (c) 2006-2008 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 BASE_BASE_DRAG_SOURCE_H_ 6 #define BASE_BASE_DRAG_SOURCE_H_ 7 8 #include <objidl.h> 9 10 #include "base/basictypes.h" 11 #include "base/ref_counted.h" 12 13 /////////////////////////////////////////////////////////////////////////////// 14 // 15 // BaseDragSource 16 // 17 // A base IDropSource implementation. Handles notifications sent by an active 18 // drag-drop operation as the user mouses over other drop targets on their 19 // system. This object tells Windows whether or not the drag should continue, 20 // and supplies the appropriate cursors. 21 // 22 class BaseDragSource : public IDropSource, 23 public base::RefCountedThreadSafe<BaseDragSource> { 24 public: 25 BaseDragSource(); ~BaseDragSource()26 virtual ~BaseDragSource() { } 27 28 // Stop the drag operation at the next chance we get. This doesn't 29 // synchronously stop the drag (since Windows is controlling that), 30 // but lets us tell Windows to cancel the drag the next chance we get. CancelDrag()31 void CancelDrag() { 32 cancel_drag_ = true; 33 } 34 35 // IDropSource implementation: 36 HRESULT __stdcall QueryContinueDrag(BOOL escape_pressed, DWORD key_state); 37 HRESULT __stdcall GiveFeedback(DWORD effect); 38 39 // IUnknown implementation: 40 HRESULT __stdcall QueryInterface(const IID& iid, void** object); 41 ULONG __stdcall AddRef(); 42 ULONG __stdcall Release(); 43 44 protected: OnDragSourceCancel()45 virtual void OnDragSourceCancel() { } OnDragSourceDrop()46 virtual void OnDragSourceDrop() { } OnDragSourceMove()47 virtual void OnDragSourceMove() { } 48 49 private: 50 // Set to true if we want to cancel the drag operation. 51 bool cancel_drag_; 52 53 DISALLOW_EVIL_CONSTRUCTORS(BaseDragSource); 54 }; 55 56 #endif // BASE_BASE_DRAG_SOURCE_H_ 57