ash/utility/partial_screenshot_controller.h

// Copyright 2014 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_UTILITY_PARTIAL_SCREENSHOT_CONTROLLER_H_
#define ASH_UTILITY_PARTIAL_SCREENSHOT_CONTROLLER_H_

#include <map>

#include "ash/ash_export.h"
#include "ash/shell_observer.h"
#include "base/memory/scoped_ptr.h"
#include "ui/events/event_handler.h"
#include "ui/gfx/display_observer.h"
#include "ui/gfx/point.h"

namespace aura {
class Window;
}

namespace ui {
class LocatedEvent;
}

namespace ash {
class ScreenshotDelegate;

// This class controls a session of taking partial screenshot, i.e.: drawing
// region rectangles during drag, and changing the mouse cursor to indicate
// the current mode.
// This class does not use aura::Window / views::Widget intentionally to avoid
// the conflicts of window manager features like mouse captures or window focus.
class ASH_EXPORT PartialScreenshotController : public ui::EventHandler,
                                               public ShellObserver,
                                               public gfx::DisplayObserver {
 public:
  // Starts the UI for taking partial screenshot; dragging to select a region.
  // PartialScreenshotController manage their own lifetime so caller must not
  // delete the returned values.
  static void StartPartialScreenshotSession(
      ScreenshotDelegate* screenshot_delegate);

  ~PartialScreenshotController() override;

 private:
  friend class PartialScreenshotControllerTest;

  class ScopedCursorSetter;
  class PartialScreenshotLayer;

  static PartialScreenshotController* GetInstanceForTest();

  PartialScreenshotController(ScreenshotDelegate* screenshot_delegate);

  // Starts, ends, cancels, or updates the region selection.
  void MaybeStart(const ui::LocatedEvent& event);
  void Complete();
  void Cancel();
  void Update(const ui::LocatedEvent& event);

  // ui::EventHandler:
  void OnKeyEvent(ui::KeyEvent* event) override;
  void OnMouseEvent(ui::MouseEvent* event) override;
  void OnTouchEvent(ui::TouchEvent* event) override;

  // ShellObserver:
  void OnAppTerminating() override;

  // gfx::DisplayObserver:
  void OnDisplayAdded(const gfx::Display& new_display) override;
  void OnDisplayRemoved(const gfx::Display& old_display) override;
  void OnDisplayMetricsChanged(const gfx::Display& display,
                               uint32_t changed_metrics) override;

  // The data to build the screenshot region.
  gfx::Point start_position_;
  aura::Window* root_window_;

  // Layers to create the visual effect of region selection.
  std::map<aura::Window*, PartialScreenshotLayer*> layers_;

  // The object to specify the crosshair cursor.
  scoped_ptr<ScopedCursorSetter> cursor_setter_;

  // ScreenshotDelegate to take the actual screenshot. No ownership.
  ScreenshotDelegate* screenshot_delegate_;

  DISALLOW_COPY_AND_ASSIGN(PartialScreenshotController);
};

}  // namespace ash

#endif  // #ifndef ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_