ui/wm/core/focus_rules.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 UI_WM_CORE_FOCUS_RULES_H_
   6 #define UI_WM_CORE_FOCUS_RULES_H_
   7
   8 #include "ui/wm/wm_export.h"
   9
  10 namespace aura {
  11 class Window;
  12 }
  13
  14 namespace wm {
  15
  16 // Implemented by an object that establishes the rules about what can be
  17 // focused or activated.
  18 class WM_EXPORT FocusRules {
  19  public:
  20   virtual ~FocusRules() {}
  21
  22   // Returns true if |window| is a toplevel window. Whether or not a window
  23   // is considered toplevel is determined by a similar set of rules that
  24   // govern activation and focus. Not all toplevel windows are activatable,
  25   // call CanActivateWindow() to determine if a window can be activated.
  26   virtual bool IsToplevelWindow(aura::Window* window) const = 0;
  27   // Returns true if |window| can be activated or focused.
  28   virtual bool CanActivateWindow(aura::Window* window) const = 0;
  29   // For CanFocusWindow(), NULL is supported, because NULL is a valid focusable
  30   // window (in the case of clearing focus).
  31   virtual bool CanFocusWindow(aura::Window* window) const = 0;
  32
  33   // Returns the toplevel window containing |window|. Not all toplevel windows
  34   // are activatable, call GetActivatableWindow() instead to return the
  35   // activatable window, which might be in a different hierarchy.
  36   // Will return NULL if |window| is not contained by a window considered to be
  37   // a toplevel window.
  38   virtual aura::Window* GetToplevelWindow(aura::Window* window) const = 0;
  39   // Returns the activatable or focusable window given an attempt to activate or
  40   // focus |window|. Some possible scenarios (not intended to be exhaustive):
  41   // - |window| is a child of a non-focusable window and so focus must be set
  42   //   according to rules defined by the delegate, e.g. to a parent.
  43   // - |window| is an activatable window that is the transient parent of a modal
  44   //   window, so attempts to activate |window| should result in the modal
  45   //   transient being activated instead.
  46   // These methods may return NULL if they are unable to find an activatable
  47   // or focusable window given |window|.
  48   virtual aura::Window* GetActivatableWindow(aura::Window* window) const = 0;
  49   virtual aura::Window* GetFocusableWindow(aura::Window* window) const = 0;
  50
  51   // Returns the next window to activate in the event that |ignore| is no longer
  52   // activatable. This function is called when something is happening to
  53   // |ignore| that means it can no longer have focus or activation, including
  54   // but not limited to:
  55   // - it or its parent hierarchy is being hidden, or removed from the
  56   //   RootWindow.
  57   // - it is being destroyed.
  58   // - it is being explicitly deactivated.
  59   // |ignore| cannot be NULL.
  60   virtual aura::Window* GetNextActivatableWindow(
  61       aura::Window* ignore) const = 0;
  62 };
  63
  64 }  // namespace wm
  65
  66 #endif  // UI_WM_CORE_FOCUS_RULES_H_