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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_
      6 #define CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_
      7 
      8 #include "base/memory/scoped_ptr.h"
      9 #include "chrome/browser/ui/panels/panel_collection.h"
     10 #include "ui/gfx/vector2d.h"
     11 
     12 class Panel;
     13 class PanelCollection;
     14 class PanelManager;
     15 namespace gfx {
     16 class Point;
     17 class Rect;
     18 }
     19 
     20 // Controls all the drags initiated for all panels, including detaching,
     21 // docking, stacking, snapping and intra-collection dragging.
     22 class PanelDragController {
     23  public:
     24   explicit PanelDragController(PanelManager* panel_manager);
     25   ~PanelDragController();
     26 
     27   // Drags the given panel.
     28   // |mouse_location| is in screen coordinate system.
     29   void StartDragging(Panel* panel, const gfx::Point& mouse_location);
     30   void Drag(const gfx::Point& mouse_location);
     31   void EndDragging(bool cancelled);
     32 
     33   // Asynchronous confirmation of panel having been closed.
     34   void OnPanelClosed(Panel* panel);
     35 
     36   bool is_dragging() const { return dragging_panel_ != NULL; }
     37   Panel* dragging_panel() const { return dragging_panel_; }
     38 
     39   // For testing.
     40   static int GetDetachDockedPanelThresholdForTesting();
     41   static int GetDockDetachedPanelThresholdForTesting();
     42   static int GetGluePanelDistanceThresholdForTesting();
     43   static int GetGluePanelOverlapThresholdForTesting();
     44   static int GetSnapPanelToScreenEdgeThresholdForTesting();
     45 
     46  private:
     47   enum GlueAction {
     48     STACK,
     49     SNAP
     50   };
     51 
     52   enum GlueEdge {
     53     TOP_EDGE,
     54     BOTTOM_EDGE,
     55     LEFT_EDGE,
     56     RIGHT_EDGE
     57   };
     58 
     59   gfx::Point GetPanelPositionForMouseLocation(
     60       const gfx::Point& mouse_location) const;
     61 
     62   // |target_position| is in screen coordinate systems. It contains the proposed
     63   //  panel origin to move to. Returns true if the request has been performed.
     64   void TryDetach(const gfx::Point& target_position);
     65   void TryDock(const gfx::Point& target_position);
     66   void TryStack(const gfx::Point& target_position);
     67   bool TryUnstackFromTop(const gfx::Point& target_position);
     68   bool TryUnstackFromBottom(const gfx::Point& target_position);
     69   void TrySnap(gfx::Point* target_position);
     70 
     71   // Finds the panel that the dragging panel with |potential_position| could
     72   // snap to or stack with. If such panel is found, |target_bounds| contains the
     73   // new bounds for the dragging panel and |target_edge| contains the matched
     74   // edge.
     75   Panel* FindPanelToGlue(const gfx::Point& potential_position,
     76                          GlueAction action,
     77                          gfx::Rect* target_bounds,
     78                          GlueEdge* target_edge) const;
     79 
     80   // Moves the |panel| (and all panels below if it is in a stack) to a different
     81   // collection.
     82   void MovePanelAndBelowToCollection(
     83       Panel* panel,
     84       PanelCollection* target_collection,
     85       PanelCollection::PositioningMask positioning_mask) const;
     86 
     87   PanelManager* panel_manager_;  // Weak, owns us.
     88   bool panel_stacking_enabled_;
     89 
     90   // Panel currently being dragged.
     91   Panel* dragging_panel_;
     92 
     93   // The original panel collection when the drag is started.
     94   PanelCollection* dragging_panel_original_collection_;
     95 
     96   // The offset from mouse location to the panel position when the drag
     97   // starts.
     98   gfx::Vector2d offset_from_mouse_location_on_drag_start_;
     99 
    100   DISALLOW_COPY_AND_ASSIGN(PanelDragController);
    101 };
    102 
    103 #endif  // CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_
    104