views/tabs/dragged_tab_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 CHROME_BROWSER_UI_VIEWS_TABS_DRAGGED_TAB_CONTROLLER_H_
#define CHROME_BROWSER_UI_VIEWS_TABS_DRAGGED_TAB_CONTROLLER_H_
#pragma once

#include "base/message_loop.h"
#include "base/scoped_ptr.h"
#include "base/timer.h"
#include "chrome/browser/tab_contents/tab_contents_delegate.h"
#include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
#include "chrome/browser/ui/tabs/dock_info.h"
#include "chrome/common/notification_observer.h"
#include "chrome/common/notification_registrar.h"
#include "ui/gfx/rect.h"

namespace views {
class View;
}
class BaseTab;
class BaseTabStrip;
class DraggedTabView;
class NativeViewPhotobooth;
class TabStripModel;

struct TabRendererData;

///////////////////////////////////////////////////////////////////////////////
//
// 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 MessageLoopForUI::Observer {
 public:
  DraggedTabController(BaseTab* source_tab,
                       BaseTabStrip* source_tabstrip);
  virtual ~DraggedTabController();

  // Returns true if there is a drag underway and the drag is attached to
  // |tab_strip|.
  // NOTE: this returns false if the dragged tab controller is in the process
  // of finishing the drag.
  static bool IsAttachedTo(BaseTabStrip* tab_strip);

  // Capture information needed to be used during a drag session for this
  // controller's associated source tab and BaseTabStrip. |mouse_offset| is the
  // distance of the mouse pointer from the tab's origin.
  void CaptureDragInfo(views::View* tab, 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);

  TabContentsWrapper* dragged_contents() { return dragged_contents_; }

  // Returns true if a drag started.
  bool started_drag() const { return started_drag_; }

 private:
  class DockDisplayer;
  friend class DockDisplayer;

  typedef std::set<gfx::NativeView> DockWindows;

  // 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,
                              const GURL& referrer,
                              WindowOpenDisposition disposition,
                              PageTransition::Type transition);
  virtual void NavigationStateChanged(const TabContents* source,
                                      unsigned changed_flags);
  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 DeactivateContents(TabContents* contents);
  virtual void LoadingStateChanged(TabContents* source);
  virtual void CloseContents(TabContents* source);
  virtual void MoveContents(TabContents* source, const gfx::Rect& pos);
  virtual void ToolbarSizeChanged(TabContents* source, bool is_animating);
  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:
#if defined(OS_WIN)
  virtual void WillProcessMessage(const MSG& msg);
  virtual void DidProcessMessage(const MSG& msg);
#else
  virtual void WillProcessEvent(GdkEvent* event);
  virtual void DidProcessEvent(GdkEvent* event);
#endif

  // Initialize the offset used to calculate the position to create windows
  // in |GetWindowCreatePoint|. This should only be invoked from
  // |CaptureDragInfo|.
  void InitWindowCreatePoint();

  // Updates the window create point from |mouse_offset_|.
  void UpdateWindowCreatePoint();

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

  void UpdateDockInfo(const gfx::Point& screen_point);

  // Sets the TabContents being dragged with the specified |new_contents|.
  void SetDraggedContents(TabContentsWrapper* 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 dragging a tab while the tab is attached.
  void MoveAttachedTab(const gfx::Point& screen_point);

  // Handles dragging while the tab is detached.
  void MoveDetachedTab(const gfx::Point& screen_point);

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

  DockInfo GetDockInfoAtPoint(const gfx::Point& screen_point);

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

  // Attach the dragged Tab to the specified TabStrip.
  void Attach(BaseTabStrip* 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.
  // |is_tab_attached| is true if the tab has already been added.
  int GetInsertionIndexForDraggedBounds(const gfx::Rect& dragged_bounds,
                                        bool is_tab_attached) 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 GetAttachedTabDragPoint(const gfx::Point& screen_point);

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

  // Does the work for EndDrag. If we actually started a drag and |how_end| is
  // not TAB_DESTROYED then one of EndDrag or RevertDrag is invoked.
  void EndDragImpl(EndDragType how_end);

  // Reverts a cancelled drag operation.
  void RevertDrag();

  // Finishes a succesful drag operation.
  void CompleteDrag();

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

  // 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(views::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();

  void DockDisplayerDestroyed(DockDisplayer* controller);

  void BringWindowUnderMouseToFront();

  // Returns the TabStripModel for the specified tabstrip.
  TabStripModel* GetModel(BaseTabStrip* tabstrip) const;

  // Handles registering for notifications.
  NotificationRegistrar registrar_;

  // The TabContentsWrapper being dragged.
  TabContentsWrapper* 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 TabStrip |source_tab_| originated from.
  BaseTabStrip* 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.
  BaseTabStrip* attached_tabstrip_;

  // If attached this is the tab we're dragging.
  BaseTab* attached_tab_;

  // 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<NativeViewPhotobooth> 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_;

  // Ratio of the x-coordinate of the mouse offset to the width of the tab.
  float offset_to_width_ratio_;

  // 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_;

  // Location of the first tab in the source tabstrip in screen coordinates.
  // This is used to calculate window_create_point_.
  gfx::Point first_source_tab_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.
  views::View* old_focused_view_;

  // The position along the major axis of the mouse cursor in screen coordinates
  // at the time of the last re-order event.
  int last_move_screen_loc_;

  DockInfo dock_info_;

  DockWindows dock_windows_;

  std::vector<DockDisplayer*> dock_controllers_;

  // Is the tab mini?
  const bool mini_;

  // Is the tab pinned?
  const bool pinned_;

  // Timer used to bring the window under the cursor to front. If the user
  // stops moving the mouse for a brief time over a browser window, it is
  // brought to front.
  base::OneShotTimer<DraggedTabController> bring_to_front_timer_;

  // Did the mouse move enough that we started a drag?
  bool started_drag_;

  // Is the drag active?
  bool active_;

  DISALLOW_COPY_AND_ASSIGN(DraggedTabController);
};

#endif  // CHROME_BROWSER_UI_VIEWS_TABS_DRAGGED_TAB_CONTROLLER_H_