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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_WM_CORE_FOCUS_RULES_H_
#define UI_WM_CORE_FOCUS_RULES_H_
#include "base/component_export.h"
namespace aura {
class Window;
}
namespace ui {
class Event;
}
namespace wm {
// Implemented by an object that establishes the rules about what can be
// focused or activated.
class COMPONENT_EXPORT(UI_WM) FocusRules {
public:
virtual ~FocusRules() {}
// Returns true if |window| is a toplevel window. Whether or not a window
// is considered toplevel is determined by a similar set of rules that
// govern activation and focus. Not all toplevel windows are activatable,
// call CanActivateWindow() to determine if a window can be activated.
virtual bool IsToplevelWindow(const aura::Window* window) const = 0;
// Returns true if |window| can be activated or focused.
virtual bool CanActivateWindow(const aura::Window* window) const = 0;
// For CanFocusWindow(), NULL window is supported, because NULL is a valid
// focusable window (in the case of clearing focus).
// If |event| is non-null it is the event triggering the focus change.
virtual bool CanFocusWindow(const aura::Window* window,
const ui::Event* event) const = 0;
// Returns the toplevel window containing |window|. Not all toplevel windows
// are activatable, call GetActivatableWindow() instead to return the
// activatable window, which might be in a different hierarchy.
// Will return NULL if |window| is not contained by a window considered to be
// a toplevel window.
virtual const aura::Window* GetToplevelWindow(
const aura::Window* window) const = 0;
// Returns the activatable or focusable window given an attempt to activate or
// focus |window|. Some possible scenarios (not intended to be exhaustive):
// - |window| is a child of a non-focusable window and so focus must be set
// according to rules defined by the delegate, e.g. to a parent.
// - |window| is an activatable window that is the transient parent of a modal
// window, so attempts to activate |window| should result in the modal
// transient being activated instead.
// These methods may return NULL if they are unable to find an activatable
// or focusable window given |window|.
virtual aura::Window* GetActivatableWindow(aura::Window* window) const = 0;
virtual aura::Window* GetFocusableWindow(aura::Window* window) const = 0;
// Returns the next window to activate in the event that |ignore| is no longer
// activatable. This function is called when something is happening to
// |ignore| that means it can no longer have focus or activation, including
// but not limited to:
// - it or its parent hierarchy is being hidden, or removed from the
// RootWindow.
// - it is being destroyed.
// - it is being explicitly deactivated.
// |ignore| cannot be NULL.
virtual aura::Window* GetNextActivatableWindow(
aura::Window* ignore) const = 0;
};
} // namespace wm
#endif // UI_WM_CORE_FOCUS_RULES_H_
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