| // Copyright 2008, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef BASE_BASE_DROP_TARGET_H__ |
| #define BASE_BASE_DROP_TARGET_H__ |
| |
| #include <atlbase.h> |
| #include <objidl.h> |
| #include <shobjidl.h> |
| |
| #include "base/basictypes.h" |
| |
| // A DropTarget implementation that takes care of the nitty gritty |
| // of dnd. While this class is concrete, subclasses will most likely |
| // want to override various OnXXX methods. |
| // |
| // Because BaseDropTarget is ref counted you shouldn't delete it directly, |
| // rather wrap it in a scoped_refptr. Be sure and invoke RevokeDragDrop(m_hWnd) |
| // before the HWND is deleted too. |
| class BaseDropTarget : public IDropTarget { |
| public: |
| // Create a new BaseDropTarget associating it with the given HWND. |
| explicit BaseDropTarget(HWND hwnd); |
| virtual ~BaseDropTarget(); |
| |
| // When suspend is set to |true|, the drop target does not receive drops from |
| // drags initiated within the owning HWND. |
| // TODO(beng): (http://b/1085385) figure out how we will handle legitimate |
| // drag-drop operations within the same HWND, such as dragging |
| // selected text to an edit field. |
| void set_suspend(bool suspend) { suspend_ = suspend; } |
| |
| // IDropTarget implementation: |
| HRESULT __stdcall DragEnter(IDataObject* data_object, |
| DWORD key_state, |
| POINTL cursor_position, |
| DWORD* effect); |
| HRESULT __stdcall DragOver(DWORD key_state, |
| POINTL cursor_position, |
| DWORD* effect); |
| HRESULT __stdcall DragLeave(); |
| HRESULT __stdcall Drop(IDataObject* data_object, |
| DWORD key_state, |
| POINTL cursor_position, |
| DWORD* effect); |
| |
| // IUnknown implementation: |
| HRESULT __stdcall QueryInterface(const IID& iid, void** object); |
| ULONG __stdcall AddRef(); |
| ULONG __stdcall Release(); |
| |
| protected: |
| // Returns the hosting HWND. |
| HWND GetHWND() { return hwnd_; } |
| |
| // Invoked when the cursor first moves over the hwnd during a dnd session. |
| // This should return a bitmask of the supported drop operations: |
| // DROPEFFECT_NONE, DROPEFFECT_COPY, DROPEFFECT_LINK and/or |
| // DROPEFFECT_MOVE. |
| virtual DWORD OnDragEnter(IDataObject* data_object, |
| DWORD key_state, |
| POINT cursor_position, |
| DWORD effect); |
| |
| // Invoked when the cursor moves over the window during a dnd session. |
| // This should return a bitmask of the supported drop operations: |
| // DROPEFFECT_NONE, DROPEFFECT_COPY, DROPEFFECT_LINK and/or |
| // DROPEFFECT_MOVE. |
| virtual DWORD OnDragOver(IDataObject* data_object, |
| DWORD key_state, |
| POINT cursor_position, |
| DWORD effect); |
| |
| // Invoked when the cursor moves outside the bounds of the hwnd during a |
| // dnd session. |
| virtual void OnDragLeave(IDataObject* data_object); |
| |
| // Invoked when the drop ends on the window. This should return the operation |
| // that was taken. |
| virtual DWORD OnDrop(IDataObject* data_object, |
| DWORD key_state, |
| POINT cursor_position, |
| DWORD effect); |
| |
| private: |
| // Returns the cached drop helper, creating one if necessary. The returned |
| // object is not addrefed. May return NULL if the object couldn't be created. |
| static IDropTargetHelper* DropHelper(); |
| |
| // The data object currently being dragged over this drop target. |
| CComPtr<IDataObject> current_data_object_; |
| |
| // A helper object that is used to provide drag image support while the mouse |
| // is dragging over the content area. |
| // |
| // DO NOT ACCESS DIRECTLY! Use DropHelper() instead, which will lazily create |
| // this if it doesn't exist yet. This object can take tens of milliseconds to |
| // create, and we don't want to block any window opening for this, especially |
| // since often, DnD will never be used. Instead, we force this penalty to the |
| // first time it is actually used. |
| static IDropTargetHelper* cached_drop_target_helper_; |
| |
| // The HWND of the source. This HWND is used to determine coordinates for |
| // mouse events that are sent to the renderer notifying various drag states. |
| HWND hwnd_; |
| |
| // Whether or not we are currently processing drag notifications for drags |
| // initiated in this window. |
| bool suspend_; |
| |
| LONG ref_count_; |
| |
| DISALLOW_EVIL_CONSTRUCTORS(BaseDropTarget); |
| }; |
| |
| #endif // BASE_BASE_DROP_TARGET_H__ |