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comparison: ipc/chromium/src/base/base_drop_target.h
ipc/chromium/src/base/base_drop_target.h
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| 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_DROP_TARGET_H_ | |
| 6 #define BASE_BASE_DROP_TARGET_H_ | |
| 7 | |
| 8 #include <objidl.h> | |
| 9 | |
| 10 #include "base/ref_counted.h" | |
| 11 | |
| 12 struct IDropTargetHelper; | |
| 13 | |
| 14 // A DropTarget implementation that takes care of the nitty gritty | |
| 15 // of dnd. While this class is concrete, subclasses will most likely | |
| 16 // want to override various OnXXX methods. | |
| 17 // | |
| 18 // Because BaseDropTarget is ref counted you shouldn't delete it directly, | |
| 19 // rather wrap it in a scoped_refptr. Be sure and invoke RevokeDragDrop(m_hWnd) | |
| 20 // before the HWND is deleted too. | |
| 21 // | |
| 22 // This class is meant to be used in a STA and is not multithread-safe. | |
| 23 class BaseDropTarget : public IDropTarget { | |
| 24 public: | |
| 25 // Create a new BaseDropTarget associating it with the given HWND. | |
| 26 explicit BaseDropTarget(HWND hwnd); | |
| 27 virtual ~BaseDropTarget(); | |
| 28 | |
| 29 // When suspend is set to |true|, the drop target does not receive drops from | |
| 30 // drags initiated within the owning HWND. | |
| 31 // TODO(beng): (http://b/1085385) figure out how we will handle legitimate | |
| 32 // drag-drop operations within the same HWND, such as dragging | |
| 33 // selected text to an edit field. | |
| 34 void set_suspend(bool suspend) { suspend_ = suspend; } | |
| 35 | |
| 36 // IDropTarget implementation: | |
| 37 HRESULT __stdcall DragEnter(IDataObject* data_object, | |
| 38 DWORD key_state, | |
| 39 POINTL cursor_position, | |
| 40 DWORD* effect); | |
| 41 HRESULT __stdcall DragOver(DWORD key_state, | |
| 42 POINTL cursor_position, | |
| 43 DWORD* effect); | |
| 44 HRESULT __stdcall DragLeave(); | |
| 45 HRESULT __stdcall Drop(IDataObject* data_object, | |
| 46 DWORD key_state, | |
| 47 POINTL cursor_position, | |
| 48 DWORD* effect); | |
| 49 | |
| 50 // IUnknown implementation: | |
| 51 HRESULT __stdcall QueryInterface(const IID& iid, void** object); | |
| 52 ULONG __stdcall AddRef(); | |
| 53 ULONG __stdcall Release(); | |
| 54 | |
| 55 protected: | |
| 56 // Returns the hosting HWND. | |
| 57 HWND GetHWND() { return hwnd_; } | |
| 58 | |
| 59 // Invoked when the cursor first moves over the hwnd during a dnd session. | |
| 60 // This should return a bitmask of the supported drop operations: | |
| 61 // DROPEFFECT_NONE, DROPEFFECT_COPY, DROPEFFECT_LINK and/or | |
| 62 // DROPEFFECT_MOVE. | |
| 63 virtual DWORD OnDragEnter(IDataObject* data_object, | |
| 64 DWORD key_state, | |
| 65 POINT cursor_position, | |
| 66 DWORD effect); | |
| 67 | |
| 68 // Invoked when the cursor moves over the window during a dnd session. | |
| 69 // This should return a bitmask of the supported drop operations: | |
| 70 // DROPEFFECT_NONE, DROPEFFECT_COPY, DROPEFFECT_LINK and/or | |
| 71 // DROPEFFECT_MOVE. | |
| 72 virtual DWORD OnDragOver(IDataObject* data_object, | |
| 73 DWORD key_state, | |
| 74 POINT cursor_position, | |
| 75 DWORD effect); | |
| 76 | |
| 77 // Invoked when the cursor moves outside the bounds of the hwnd during a | |
| 78 // dnd session. | |
| 79 virtual void OnDragLeave(IDataObject* data_object); | |
| 80 | |
| 81 // Invoked when the drop ends on the window. This should return the operation | |
| 82 // that was taken. | |
| 83 virtual DWORD OnDrop(IDataObject* data_object, | |
| 84 DWORD key_state, | |
| 85 POINT cursor_position, | |
| 86 DWORD effect); | |
| 87 | |
| 88 // Return the drag identity. | |
| 89 static int32_t GetDragIdentity() { return drag_identity_; } | |
| 90 | |
| 91 private: | |
| 92 // Returns the cached drop helper, creating one if necessary. The returned | |
| 93 // object is not addrefed. May return NULL if the object couldn't be created. | |
| 94 static IDropTargetHelper* DropHelper(); | |
| 95 | |
| 96 // The data object currently being dragged over this drop target. | |
| 97 scoped_refptr<IDataObject> current_data_object_; | |
| 98 | |
| 99 // A helper object that is used to provide drag image support while the mouse | |
| 100 // is dragging over the content area. | |
| 101 // | |
| 102 // DO NOT ACCESS DIRECTLY! Use DropHelper() instead, which will lazily create | |
| 103 // this if it doesn't exist yet. This object can take tens of milliseconds to | |
| 104 // create, and we don't want to block any window opening for this, especially | |
| 105 // since often, DnD will never be used. Instead, we force this penalty to the | |
| 106 // first time it is actually used. | |
| 107 static IDropTargetHelper* cached_drop_target_helper_; | |
| 108 | |
| 109 // The drag identity (id). An up-counter that increases when the cursor first | |
| 110 // moves over the HWND in a DnD session (OnDragEnter). 0 is reserved to mean | |
| 111 // the "no/unknown" identity, and is used for initialization. The identity is | |
| 112 // sent to the renderer in drag enter notifications. Note: the identity value | |
| 113 // is passed over the renderer NPAPI interface to gears, so use int32_t instead | |
| 114 // of int here. | |
| 115 static int32_t drag_identity_; | |
| 116 | |
| 117 // The HWND of the source. This HWND is used to determine coordinates for | |
| 118 // mouse events that are sent to the renderer notifying various drag states. | |
| 119 HWND hwnd_; | |
| 120 | |
| 121 // Whether or not we are currently processing drag notifications for drags | |
| 122 // initiated in this window. | |
| 123 bool suspend_; | |
| 124 | |
| 125 LONG ref_count_; | |
| 126 | |
| 127 DISALLOW_EVIL_CONSTRUCTORS(BaseDropTarget); | |
| 128 }; | |
| 129 | |
| 130 #endif // BASE_BASE_DROP_TARGET_H_ |
