V2

ui/views/events/drag_controller.h

+// Copyright (c) 2011 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_EVENTS_DRAG_CONTROLLER_H_
+#define UI_VIEWS_EVENTS_DRAG_CONTROLLER_H_
+#pragma once
+
+namespace ui {
+
+// DragController is responsible for writing drag data for a View, as well as
+// supplying the supported drag operations without having to subclass View.
+class DragController {
+ public:
+  // Writes the data for the drag.
+  virtual void WriteDragData(View* sender,
+                             const gfx::Point& press_pt,
+                             OSExchangeData* data) = 0;
+
+  // Returns the supported drag operations (see DragDropTypes for possible
+  // values). A drag is only started if this returns a non-zero value.
+  virtual int GetDragOperations(View* sender, const gfx::Point& p) = 0;
+
+  // Returns true if a drag operation can be started.
+  // |press_pt| represents the coordinates where the mouse was initially
+  // pressed down. |p| is the current mouse coordinates.
+  virtual bool CanStartDrag(View* sender,
+                            const gfx::Point& press_pt,
+                            const gfx::Point& p) = 0;
+
+ protected:
+  virtual ~DragController() {}
+};
+
+}  // namespace ui
+
+#endif  // UI_VIEWS_EVENTS_DRAG_CONTROLLER_H_