path: root/chrome/browser/tabs/dragged_tab_controller.h

// Copyright (c) 2006-2008 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 CHROME_BROWSER_TABS_DRAGGED_TAB_CONTROLLER_H_
#define CHROME_BROWSER_TABS_DRAGGED_TAB_CONTROLLER_H_

#include "base/gfx/rect.h"
#include "base/message_loop.h"
#include "chrome/browser/tab_contents_delegate.h"
#include "chrome/browser/tabs/tab_renderer.h"
#include "chrome/common/notification_service.h"

namespace ChromeViews {
class MouseEvent;
class View;
}
class DraggedTabView;
class HWNDPhotobooth;
class SkBitmap;
class Tab;
class TabStrip;
class TabStripModel;

///////////////////////////////////////////////////////////////////////////////
//
// DraggedTabController
//
//  An object that handles a drag session for an individual Tab within a
//  TabStrip. This object is created whenever the mouse is pressed down on a
//  Tab and destroyed when the mouse is released or the drag operation is
//  aborted. The Tab that the user dragged (the "source tab") owns this object
//  and must be the only one to destroy it (via |DestroyDragController|).
//
///////////////////////////////////////////////////////////////////////////////
class DraggedTabController : public TabContentsDelegate,
                             public NotificationObserver,
                             public MessageLoop::Observer{
 public:
  DraggedTabController(Tab* source_tab, TabStrip* source_tabstrip);
  virtual ~DraggedTabController();

  // Capture information needed to be used during a drag session for this
  // controller's associated source Tab and TabStrip. |mouse_offset| is the
  // distance of the mouse pointer from the Tab's origin.
  void CaptureDragInfo(const gfx::Point& mouse_offset);

  // Responds to drag events subsequent to StartDrag. If the mouse moves a
  // sufficient distance before the mouse is released, a drag session is
  // initiated.
  void Drag();

  // Complete the current drag session. If the drag session was canceled
  // because the user pressed Escape or something interrupted it, |canceled|
  // is true so the helper can revert the state to the world before the drag
  // begun.
  void EndDrag(bool canceled);

  // Retrieve the source Tab if the TabContents specified matches the one being
  // dragged by this controller, or NULL if the specified TabContents is not
  // the same as the one being dragged.
  Tab* GetDragSourceTabForContents(TabContents* contents) const;

  // Returns true if the specified Tab matches the Tab being dragged.
  bool IsDragSourceTab(Tab* tab) const;

 private:
  // Enumeration of the ways a drag session can end.
  enum EndDragType {
    // Drag session exited normally: the user released the mouse.
    NORMAL,

    // The drag session was canceled (alt-tab during drag, escape ...)
    CANCELED,

    // The tab (NavigationController) was destroyed during the drag.
    TAB_DESTROYED
  };

  // Overridden from TabContentsDelegate:
  virtual void OpenURLFromTab(TabContents* source,
                              const GURL& url,
                              WindowOpenDisposition disposition,
                              PageTransition::Type transition,
                              const std::string& override_encoding);
  virtual void NavigationStateChanged(const TabContents* source,
                                      unsigned changed_flags);
  virtual void ReplaceContents(TabContents* source,
                               TabContents* new_contents);
  virtual void AddNewContents(TabContents* source,
                              TabContents* new_contents,
                              WindowOpenDisposition disposition,
                              const gfx::Rect& initial_pos,
                              bool user_gesture);
  virtual void ActivateContents(TabContents* contents);
  virtual void LoadingStateChanged(TabContents* source);
  virtual void CloseContents(TabContents* source);
  virtual void MoveContents(TabContents* source, const gfx::Rect& pos);
  virtual bool IsPopup(TabContents* source);
  virtual void ToolbarSizeChanged(TabContents* source, bool is_animating);
  virtual void URLStarredChanged(TabContents* source, bool starred);
  virtual void UpdateTargetURL(TabContents* source, const GURL& url);

  // Overridden from NotificationObserver:
  virtual void Observe(NotificationType type,
                       const NotificationSource& source,
                       const NotificationDetails& details);

  // Overridden from MessageLoop::Observer:
  virtual void WillProcessMessage(const MSG& msg);
  virtual void DidProcessMessage(const MSG& msg);

  // Initialize the offset used to calculate the position to create windows
  // in |GetWindowCreatePoint|.
  void InitWindowCreatePoint();

  // Returns the point where a detached window should be created given the
  // current mouse position.
  gfx::Point GetWindowCreatePoint() const;

  // Replaces the TabContents being dragged with the specified |new_contents|.
  // This can occur if the active TabContents for the tab being dragged is
  // replaced, e.g. if a transition from one TabContentsType to another occurs
  // during the drag.
  void ChangeDraggedContents(TabContents* new_contents);

  // Saves focus in the window that the drag initiated from. Focus will be
  // restored appropriately if the drag ends within this same window.
  void SaveFocus();

  // Restore focus to the View that had focus before the drag was started, if
  // the drag ends within the same Window as it began.
  void RestoreFocus();

  // Tests whether the position of the mouse is past a minimum elasticity
  // threshold required to start a drag.
  bool CanStartDrag() const;

  // Move the DraggedTabView according to the current mouse screen position,
  // potentially updating the source and other TabStrips.
  void ContinueDragging();

  // Handles moving the Tab within a TabStrip as well as updating the View.
  void MoveTab(const gfx::Point& screen_point);

  // Returns the compatible TabStrip that is under the specified point (screen
  // coordinates), or NULL if there is none.
  TabStrip* GetTabStripForPoint(const gfx::Point& screen_point) const;

  // Returns the specified |tabstrip| if it contains the specified point
  // (screen coordinates), NULL if it does not.
  TabStrip* GetTabStripIfItContains(TabStrip* tabstrip,
                                    const gfx::Point& screen_point) const;

  // Attach the dragged Tab to the specified TabStrip.
  void Attach(TabStrip* attached_tabstrip, const gfx::Point& screen_point);

  // Detach the dragged Tab from the current TabStrip.
  void Detach();

  // Returns the index where the dragged TabContents should be inserted into
  // the attached TabStripModel given the DraggedTabView's bounds
  // |dragged_bounds| in coordinates relative to the attached TabStrip.
  int GetInsertionIndexForDraggedBounds(const gfx::Rect& dragged_bounds) const;

  // Retrieve the bounds of the DraggedTabView, relative to the attached
  // TabStrip, given location of the dragged tab in screen coordinates.
  gfx::Rect GetDraggedViewTabStripBounds(const gfx::Point& screen_point);

  // Get the position of the dragged tab view relative to the attached tab
  // strip.
  gfx::Point GetDraggedViewPoint(const gfx::Point& screen_point);

  // Finds the Tab within the specified TabStrip that corresponds to the
  // dragged TabContents.
  Tab* GetTabMatchingDraggedContents(TabStrip* tabstrip) const;

  // Does the work for EndDrag.
  void EndDragImpl(EndDragType how_end);

  // If the drag was aborted for some reason, this function is called to un-do
  // the changes made during the drag operation.
  void RevertDrag();

  // Finishes the drag operation. Returns true if the drag controller should
  // be destroyed immediately, false otherwise.
  bool CompleteDrag();

  // Create the DraggedTabView, if it does not yet exist.
  void EnsureDraggedView();

  // Utility for getting the mouse position in screen coordinates.
  gfx::Point GetCursorScreenPoint() const;

  // Returns the bounds (in screen coordinates) of the specified View.
  gfx::Rect GetViewScreenBounds(ChromeViews::View* tabstrip) const;

  // Utility to convert the specified TabStripModel index to something valid
  // for the attached TabStrip.
  int NormalizeIndexToAttachedTabStrip(int index) const;

  // Hides the frame for the window that contains the TabStrip the current
  // drag session was initiated from.
  void HideFrame();

  // Closes a hidden frame at the end of a drag session.
  void CleanUpHiddenFrame();

  // Cleans up a source tab that is no longer used.
  void CleanUpSourceTab();

  // Completes the drag session after the view has animated to its final
  // position.
  void OnAnimateToBoundsComplete();

  // The TabContents being dragged. This can get replaced during the drag if
  // the associated NavigationController is navigated to a different
  // TabContentsType.
  TabContents* dragged_contents_;

  // The original TabContentsDelegate of |dragged_contents_|, before it was
  // detached from the browser window. We store this so that we can forward
  // certain delegate notifications back to it if we can't handle them locally.
  TabContentsDelegate* original_delegate_;

  // The Tab that initiated the drag session.
  Tab* source_tab_;

  // The TabStrip |source_tab_| originated from.
  TabStrip* source_tabstrip_;

  // This is the index of the |source_tab_| in |source_tabstrip_| when the drag
  // began. This is used to restore the previous state if the drag is aborted.
  int source_model_index_;

  // The TabStrip the dragged Tab is currently attached to, or NULL if the
  // dragged Tab is detached.
  TabStrip* attached_tabstrip_;

  // The visual representation of the dragged Tab.
  scoped_ptr<DraggedTabView> view_;

  // The photo-booth the TabContents sits in when the Tab is detached, to
  // obtain screen shots.
  scoped_ptr<HWNDPhotobooth> photobooth_;

  // The position of the mouse (in screen coordinates) at the start of the drag
  // operation. This is used to calculate minimum elasticity before a
  // DraggedTabView is constructed.
  gfx::Point start_screen_point_;

  // This is the offset of the mouse from the top left of the Tab where
  // dragging begun. This is used to ensure that the dragged view is always
  // positioned at the correct location during the drag, and to ensure that the
  // detached window is created at the right location.
  gfx::Point mouse_offset_;

  // A hint to use when positioning new windows created by detaching Tabs. This
  // is the distance of the mouse from the top left of the dragged tab as if it
  // were the distance of the mouse from the top left of the first tab in the
  // attached TabStrip from the top left of the window.
  gfx::Point window_create_point_;

  // The bounds of the browser window before the last Tab was detached. When
  // the last Tab is detached, rather than destroying the frame (which would
  // abort the drag session), the frame is moved off-screen. If the drag is
  // aborted (e.g. by the user pressing Esc, or capture being lost), the Tab is
  // attached to the hidden frame and the frame moved back to these bounds.
  gfx::Rect restore_bounds_;

  // The last view that had focus in the window containing |source_tab_|. This
  // is saved so that focus can be restored properly when a drag begins and
  // ends within this same window.
  ChromeViews::View* old_focused_view_;

  bool in_destructor_;

  // The horizontal position of the mouse cursor in screen coordinates at the
  // time of the last re-order event.
  int last_move_screen_x_;

  DISALLOW_COPY_AND_ASSIGN(DraggedTabController);
};

#endif  // CHROME_BROWSER_TABS_DRAGGED_TAB_CONTROLLER_H_