chrome/browser/ui/tabs/tab_strip_model_observer.h

   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_TABS_TAB_STRIP_MODEL_OBSERVER_H_
   6 #define CHROME_BROWSER_UI_TABS_TAB_STRIP_MODEL_OBSERVER_H_
   7
   8 class TabStripModel;
   9
  10 namespace content {
  11 class WebContents;
  12 }
  13
  14 namespace ui {
  15 class ListSelectionModel;
  16 }
  17
  18 ////////////////////////////////////////////////////////////////////////////////
  19 //
  20 // TabStripModelObserver
  21 //
  22 //  Objects implement this interface when they wish to be notified of changes
  23 //  to the TabStripModel.
  24 //
  25 //  Two major implementers are the TabStrip, which uses notifications sent
  26 //  via this interface to update the presentation of the strip, and the Browser
  27 //  object, which updates bookkeeping and shows/hides individual WebContentses.
  28 //
  29 //  Register your TabStripModelObserver with the TabStripModel using its
  30 //  Add/RemoveObserver methods.
  31 //
  32 ////////////////////////////////////////////////////////////////////////////////
  33 class TabStripModelObserver {
  34  public:
  35   // Enumeration of the possible values supplied to TabChangedAt.
  36   enum TabChangeType {
  37     // Only the loading state changed.
  38     LOADING_ONLY,
  39
  40     // Only the title changed and page isn't loading.
  41     TITLE_NOT_LOADING,
  42
  43     // Change not characterized by LOADING_ONLY or TITLE_NOT_LOADING.
  44     ALL
  45   };
  46
  47   enum ChangeReason {
  48     // Used to indicate that none of the reasons below are responsible for the
  49     // active tab change.
  50     CHANGE_REASON_NONE = 0,
  51     // The active tab changed because the tab's web contents was replaced.
  52     CHANGE_REASON_REPLACED = 1 << 0,
  53     // The active tab changed due to a user input event.
  54     CHANGE_REASON_USER_GESTURE = 1 << 1,
  55   };
  56
  57   // A new WebContents was inserted into the TabStripModel at the
  58   // specified index. |foreground| is whether or not it was opened in the
  59   // foreground (selected).
  60   virtual void TabInsertedAt(content::WebContents* contents,
  61                              int index,
  62                              bool foreground);
  63
  64   // The specified WebContents at |index| is being closed (and eventually
  65   // destroyed). |tab_strip_model| is the TabStripModel that contained the tab.
  66   virtual void TabClosingAt(TabStripModel* tab_strip_model,
  67                             content::WebContents* contents,
  68                             int index);
  69
  70   // The specified WebContents at |index| is being detached, perhaps to
  71   // be inserted in another TabStripModel. The implementer should take whatever
  72   // action is necessary to deal with the WebContents no longer being
  73   // present.
  74   virtual void TabDetachedAt(content::WebContents* contents, int index);
  75
  76   // The active WebContents is about to change from |old_contents|.
  77   // This gives observers a chance to prepare for an impending switch before it
  78   // happens.
  79   virtual void TabDeactivated(content::WebContents* contents);
  80
  81   // Sent when the active tab changes. The previously active tab is identified
  82   // by |old_contents| and the newly active tab by |new_contents|. |index| is
  83   // the index of |new_contents|. If |reason| has CHANGE_REASON_REPLACED set
  84   // then the web contents was replaced (see TabChangedAt). If |reason| has
  85   // CHANGE_REASON_USER_GESTURE set then the web contents was changed due to a
  86   // user input event (e.g. clicking on a tab, keystroke).
  87   // Note: It is possible for the selection to change while the active tab
  88   // remains unchanged. For example, control-click may not change the active tab
  89   // but does change the selection. In this case |ActiveTabChanged| is not sent.
  90   // If you care about any changes to the selection, override
  91   // TabSelectionChanged.
  92   // Note: |old_contents| will be NULL if there was no contents previously
  93   // active.
  94   virtual void ActiveTabChanged(content::WebContents* old_contents,
  95                                 content::WebContents* new_contents,
  96                                 int index,
  97                                 int reason);
  98
  99   // Sent when the selection changes in |tab_strip_model|. More precisely when
 100   // selected tabs, anchor tab or active tab change. |old_model| is a snapshot
 101   // of the selection model before the change. See also ActiveTabChanged for
 102   // details.
 103   virtual void TabSelectionChanged(TabStripModel* tab_strip_model,
 104                                    const ui::ListSelectionModel& old_model);
 105
 106   // The specified WebContents at |from_index| was moved to |to_index|.
 107   virtual void TabMoved(content::WebContents* contents,
 108                         int from_index,
 109                         int to_index);
 110
 111   // The specified WebContents at |index| changed in some way. |contents|
 112   // may be an entirely different object and the old value is no longer
 113   // available by the time this message is delivered.
 114   //
 115   // See TabChangeType for a description of |change_type|.
 116   virtual void TabChangedAt(content::WebContents* contents,
 117                             int index,
 118                             TabChangeType change_type);
 119
 120   // The WebContents was replaced at the specified index. This is invoked
 121   // when instant is enabled and the user navigates by way of instant or when
 122   // prerendering swaps in a prerendered WebContents.
 123   virtual void TabReplacedAt(TabStripModel* tab_strip_model,
 124                              content::WebContents* old_contents,
 125                              content::WebContents* new_contents,
 126                              int index);
 127
 128   // Invoked when the pinned state of a tab changes.
 129   virtual void TabPinnedStateChanged(content::WebContents* contents, int index);
 130
 131   // Invoked when the blocked state of a tab changes.
 132   // NOTE: This is invoked when a tab becomes blocked/unblocked by a tab modal
 133   // window.
 134   virtual void TabBlockedStateChanged(content::WebContents* contents,
 135                                       int index);
 136
 137   // The TabStripModel now no longer has any tabs. The implementer may
 138   // use this as a trigger to try and close the window containing the
 139   // TabStripModel, for example...
 140   virtual void TabStripEmpty();
 141
 142   // Sent any time an attempt is made to close all the tabs. This is not
 143   // necessarily the result of CloseAllTabs(). For example, if the user closes
 144   // the last tab WillCloseAllTabs() is sent. If the close does not succeed
 145   // during the current event (say unload handlers block it) then
 146   // CloseAllTabsCanceled() is sent. Also note that if the last tab is detached
 147   // (DetachWebContentsAt()) then this is not sent.
 148   virtual void WillCloseAllTabs();
 149   virtual void CloseAllTabsCanceled();
 150
 151   // Sent when the tabstrip model is about to be deleted and any reference held
 152   // must be dropped.
 153   virtual void TabStripModelDeleted();
 154
 155  protected:
 156   virtual ~TabStripModelObserver() {}
 157 };
 158
 159 #endif  // CHROME_BROWSER_UI_TABS_TAB_STRIP_MODEL_OBSERVER_H_