Don't preload rarely seen large images

[chromium-blink-merge.git] / ash / accelerators / accelerator_controller.h

// Copyright (c) 2012 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 ASH_ACCELERATORS_ACCELERATOR_CONTROLLER_H_
#define ASH_ACCELERATORS_ACCELERATOR_CONTROLLER_H_

#include <map>
#include <set>

#include "ash/accelerators/accelerator_table.h"
#include "ash/accelerators/exit_warning_handler.h"
#include "ash/ash_export.h"
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/memory/scoped_ptr.h"
#include "ui/base/accelerators/accelerator.h"
#include "ui/base/accelerators/accelerator_history.h"

namespace ui {
class AcceleratorManager;
}

namespace ash {

struct AcceleratorData;
class BrightnessControlDelegate;
class ExitWarningHandler;
class ImeControlDelegate;
class KeyboardBrightnessControlDelegate;
class ScreenshotDelegate;
class VolumeControlDelegate;

// AcceleratorController provides functions for registering or unregistering
// global keyboard accelerators, which are handled earlier than any windows. It
// also implements several handlers as an accelerator target.
class ASH_EXPORT AcceleratorController : public ui::AcceleratorTarget {
 public:
  AcceleratorController();
  ~AcceleratorController() override;

  // A list of possible ways in which an accelerator should be restricted before
  // processing. Any target registered with this controller should respect
  // restrictions by calling |GetCurrentAcceleratorRestriction| during
  // processing.
  enum AcceleratorProcessingRestriction {
    // Process the accelerator normally.
    RESTRICTION_NONE,

    // Don't process the accelerator.
    RESTRICTION_PREVENT_PROCESSING,

    // Don't process the accelerator and prevent propagation to other targets.
    RESTRICTION_PREVENT_PROCESSING_AND_PROPAGATION
  };

  // Registers a global keyboard accelerator for the specified target. If
  // multiple targets are registered for an accelerator, a target registered
  // later has higher priority.
  void Register(const ui::Accelerator& accelerator,
                ui::AcceleratorTarget* target);

  // Unregisters the specified keyboard accelerator for the specified target.
  void Unregister(const ui::Accelerator& accelerator,
                  ui::AcceleratorTarget* target);

  // Unregisters all keyboard accelerators for the specified target.
  void UnregisterAll(ui::AcceleratorTarget* target);

  // Activates the target associated with the specified accelerator.
  // First, AcceleratorPressed handler of the most recently registered target
  // is called, and if that handler processes the event (i.e. returns true),
  // this method immediately returns. If not, we do the same thing on the next
  // target, and so on.
  // Returns true if an accelerator was activated.
  bool Process(const ui::Accelerator& accelerator);

  // Returns true if the |accelerator| is registered.
  bool IsRegistered(const ui::Accelerator& accelerator) const;

  // Returns true if the |accelerator| is preferred. A preferred accelerator
  // is handled before being passed to an window/web contents, unless
  // the window is in fullscreen state.
  bool IsPreferred(const ui::Accelerator& accelerator) const;

  // Returns true if the |accelerator| is reserved. A reserved accelerator
  // is always handled and will never be passed to an window/web contents.
  bool IsReserved(const ui::Accelerator& accelerator) const;

  // Performs the specified action if it is enabled. Returns whether the action
  // was performed successfully.
  bool PerformActionIfEnabled(AcceleratorAction action);

  // Returns the restriction for the current context.
  AcceleratorProcessingRestriction GetCurrentAcceleratorRestriction();

  void SetBrightnessControlDelegate(
      scoped_ptr<BrightnessControlDelegate> brightness_control_delegate);
  void SetImeControlDelegate(
      scoped_ptr<ImeControlDelegate> ime_control_delegate);
  void SetScreenshotDelegate(
      scoped_ptr<ScreenshotDelegate> screenshot_delegate);
  BrightnessControlDelegate* brightness_control_delegate() const {
    return brightness_control_delegate_.get();
  }
  ScreenshotDelegate* screenshot_delegate() {
    return screenshot_delegate_.get();
  }

  // Provides access to the ExitWarningHandler for testing.
  ExitWarningHandler* GetExitWarningHandlerForTest() {
    return &exit_warning_handler_;
  }

  ui::AcceleratorHistory* accelerator_history() {
    return accelerator_history_.get();
  }

  // Overridden from ui::AcceleratorTarget:
  bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
  bool CanHandleAccelerators() const override;

 private:
  FRIEND_TEST_ALL_PREFIXES(AcceleratorControllerTest, GlobalAccelerators);
  FRIEND_TEST_ALL_PREFIXES(AcceleratorControllerTest,
                           DontRepeatToggleFullscreen);

  // Initializes the accelerators this class handles as a target.
  void Init();

  // Registers the specified accelerators.
  void RegisterAccelerators(const AcceleratorData accelerators[],
                            size_t accelerators_length);

  // Returns whether |action| can be performed. The |accelerator| may provide
  // additional data the action needs.
  bool CanPerformAction(AcceleratorAction action,
                        const ui::Accelerator& accelerator);

  // Performs the specified action. The |accelerator| may provide additional
  // data the action needs.
  void PerformAction(AcceleratorAction action,
                     const ui::Accelerator& accelerator);

  // Returns whether performing |action| should consume the key event.
  bool ShouldActionConsumeKeyEvent(AcceleratorAction action);

  // Get the accelerator restriction for the given action. Supply an |action|
  // of -1 to get restrictions that apply for the current context.
  AcceleratorProcessingRestriction GetAcceleratorProcessingRestriction(
      int action);

  void SetKeyboardBrightnessControlDelegate(
      scoped_ptr<KeyboardBrightnessControlDelegate>
      keyboard_brightness_control_delegate);

  scoped_ptr<ui::AcceleratorManager> accelerator_manager_;

  // A tracker for the current and previous accelerators.
  scoped_ptr<ui::AcceleratorHistory> accelerator_history_;

  // TODO(derat): BrightnessControlDelegate is also used by the system tray;
  // move it outside of this class.
  scoped_ptr<BrightnessControlDelegate> brightness_control_delegate_;
  scoped_ptr<ImeControlDelegate> ime_control_delegate_;
  scoped_ptr<KeyboardBrightnessControlDelegate>
      keyboard_brightness_control_delegate_;
  scoped_ptr<ScreenshotDelegate> screenshot_delegate_;

  // Handles the exit accelerator which requires a double press to exit and
  // shows a popup with an explanation.
  ExitWarningHandler exit_warning_handler_;

  // A map from accelerators to the AcceleratorAction values, which are used in
  // the implementation.
  std::map<ui::Accelerator, AcceleratorAction> accelerators_;

  // Actions allowed when the user is not signed in.
  std::set<int> actions_allowed_at_login_screen_;
  // Actions allowed when the screen is locked.
  std::set<int> actions_allowed_at_lock_screen_;
  // Actions allowed when a modal window is up.
  std::set<int> actions_allowed_at_modal_window_;
  // Preferred actions. See accelerator_table.h for details.
  std::set<int> preferred_actions_;
  // Reserved actions. See accelerator_table.h for details.
  std::set<int> reserved_actions_;
  // Actions which will not be repeated while holding the accelerator key.
  std::set<int> nonrepeatable_actions_;
  // Actions allowed in app mode.
  std::set<int> actions_allowed_in_app_mode_;
  // Actions disallowed if there are no windows.
  std::set<int> actions_needing_window_;

  DISALLOW_COPY_AND_ASSIGN(AcceleratorController);
};

}  // namespace ash

#endif  // ASH_ACCELERATORS_ACCELERATOR_CONTROLLER_H_