Add base to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 142 insertions, 0 deletions

diff --git a/base/base_drop_target.h b/base/base_drop_target.h
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+++ b/base/base_drop_target.h
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+// 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
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// 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__