Get drag and drop working for win aura.

ui/views/widget/desktop_aura/desktop_drop_target_win.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTIOP_DROP_TARGET_WIN_H_
+#define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTIOP_DROP_TARGET_WIN_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "ui/base/dragdrop/drop_target.h"
+#include "ui/aura/window_observer.h"
+
+namespace aura {
+class RootWindow;
+namespace client {
+class DragDropDelegate;
+}
+}
+
+namespace ui {
+class DropTargetEvent;
+class OSExchangeData;
+}
+
+namespace views {
+
+// DesktopDropTargetWin takes care of managing drag and drop for
+// DesktopRootWindowHostWin. It converts Windows OLE drop messages into
+// aura::client::DragDropDelegate calls.
+class DesktopDropTargetWin : public ui::DropTarget,
+                             public aura::WindowObserver {
+ public:
+  DesktopDropTargetWin(aura::RootWindow* root_window, HWND window);
+  virtual ~DesktopDropTargetWin();
+
+ private:
+  // ui::DropTarget implementation:
+  virtual DWORD OnDragEnter(IDataObject* data_object,
+                            DWORD key_state,
+                            POINT position,
+                            DWORD effect) OVERRIDE;
+  virtual DWORD OnDragOver(IDataObject* data_object,
+                           DWORD key_state,
+                           POINT position,
+                           DWORD effect) OVERRIDE;
+  virtual void OnDragLeave(IDataObject* data_object) OVERRIDE;
+  virtual DWORD OnDrop(IDataObject* data_object,
+                       DWORD key_state,
+                       POINT position,
+                       DWORD effect) OVERRIDE;
+
+  // aura::WindowObserver implementation:
+  virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
+
+  // Common functionality for the ui::DropTarget methods to translate from COM
+  // data types to Aura ones.
+  void Translate(IDataObject* data_object,
+                 DWORD key_state,
+                 POINT cursor_position,
+                 DWORD effect,
+                 scoped_ptr<ui::OSExchangeData>* data,
+                 scoped_ptr<ui::DropTargetEvent>* event,
+                 aura::client::DragDropDelegate** delegate);
+
+  void NotifyDragLeave();
+
+  // The root window associated with this drop target.
+  aura::RootWindow* root_window_;
+
+  // The Aura window that is currently under the cursor. We need to manually
+  // keep track of this because Windows will only call our drag enter method
+  // once when the user enters the associated HWND. But inside that HWND there
+  // could be multiple aura windows, so we need to generate drag enter events
+  // for them.
+  aura::Window* target_window_;
+
+  DISALLOW_COPY_AND_ASSIGN(DesktopDropTargetWin);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTIOP_DROP_TARGET_WIN_H_