| // 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_WIDGET_DROP_HELPER_H_ |
| #define UI_VIEWS_WIDGET_DROP_HELPER_H_ |
| |
| #include "base/basictypes.h" |
| |
| namespace gfx { |
| class Point; |
| } // namespace gfx |
| |
| namespace ui { |
| class OSExchangeData; |
| } // namespace ui |
| using ui::OSExchangeData; |
| |
| namespace views { |
| |
| class RootView; |
| class View; |
| |
| // DropHelper provides support for managing the view a drop is going to occur |
| // at during dnd as well as sending the view the appropriate dnd methods. |
| // DropHelper is intended to be used by a class that interacts with the system |
| // drag and drop. The system class invokes OnDragOver as the mouse moves, |
| // then either OnDragExit or OnDrop when the drop is done. |
| class DropHelper { |
| public: |
| explicit DropHelper(View* root_view); |
| ~DropHelper(); |
| |
| // Current view drop events are targeted at, may be NULL. |
| View* target_view() const { return target_view_; } |
| |
| // Returns the RootView the DropHelper was created with. |
| View* root_view() const { return root_view_; } |
| |
| // Resets the target_view_ to NULL if it equals view. |
| // |
| // This is invoked when a View is removed from the RootView to make sure |
| // we don't target a view that was removed during dnd. |
| void ResetTargetViewIfEquals(View* view); |
| |
| // Invoked when a the mouse is dragged over the root view during a drag and |
| // drop operation. This method returns a bitmask of the types in DragDropTypes |
| // for the target view. If no view wants the drop, DRAG_NONE is returned. |
| int OnDragOver(const OSExchangeData& data, |
| const gfx::Point& root_view_location, |
| int drag_operation); |
| |
| // Invoked when a the mouse is dragged out of the root view during a drag and |
| // drop operation. |
| void OnDragExit(); |
| |
| // Invoked when the user drops data on the root view during a drag and drop |
| // operation. See OnDragOver for details on return type. |
| // |
| // NOTE: implementations must invoke OnDragOver before invoking this, |
| // supplying the return value from OnDragOver as the drag_operation. |
| int OnDrop(const OSExchangeData& data, |
| const gfx::Point& root_view_location, |
| int drag_operation); |
| |
| // Calculates the target view for a drop given the specified location in |
| // the coordinate system of the rootview. This tries to avoid continually |
| // querying CanDrop by returning target_view_ if the mouse is still over |
| // target_view_. |
| View* CalculateTargetView(const gfx::Point& root_view_location, |
| const OSExchangeData& data, |
| bool check_can_drop); |
| |
| private: |
| // Implementation of CalculateTargetView. If |deepest_view| is non-NULL it is |
| // set to the deepest descendant of the RootView that contains the point |
| // |root_view_location| |
| View* CalculateTargetViewImpl(const gfx::Point& root_view_location, |
| const OSExchangeData& data, |
| bool check_can_drop, |
| View** deepest_view); |
| |
| // Methods to send the appropriate drop notification to the targeted view. |
| // These do nothing if the target view is NULL. |
| void NotifyDragEntered(const OSExchangeData& data, |
| const gfx::Point& root_view_location, |
| int drag_operation); |
| int NotifyDragOver(const OSExchangeData& data, |
| const gfx::Point& root_view_location, |
| int drag_operation); |
| void NotifyDragExit(); |
| |
| // RootView we were created for. |
| View* root_view_; |
| |
| // View we're targeting events at. |
| View* target_view_; |
| |
| // The deepest view under the current drop coordinate. |
| View* deepest_view_; |
| |
| DISALLOW_COPY_AND_ASSIGN(DropHelper); |
| }; |
| |
| } // namespace views |
| |
| #endif // UI_VIEWS_WIDGET_DROP_HELPER_H_ |