views/controls/throbber.h

// Copyright (c) 2011 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.

// Throbbers display an animation, usually used as a status indicator.

#ifndef VIEWS_CONTROLS_THROBBER_H_
#define VIEWS_CONTROLS_THROBBER_H_
#pragma once

#include "base/basictypes.h"
#include "base/time.h"
#include "base/timer.h"
#include "views/view.h"

class SkBitmap;

namespace views {

class VIEWS_EXPORT Throbber : public View {
 public:
  // |frame_time_ms| is the amount of time that should elapse between frames
  //                 (in milliseconds)
  // If |paint_while_stopped| is false, this view will be invisible when not
  // running.
  Throbber(int frame_time_ms, bool paint_while_stopped);
  Throbber(int frame_time_ms, bool paint_while_stopped, SkBitmap* frames);
  virtual ~Throbber();

  // Start and stop the throbber animation
  virtual void Start();
  virtual void Stop();

  // Set custom throbber frames. Otherwise IDR_THROBBER is loaded.
  void SetFrames(SkBitmap* frames);

  // overridden from View
  virtual gfx::Size GetPreferredSize();
  virtual void OnPaint(gfx::Canvas* canvas);

 protected:
  // Specifies whether the throbber is currently animating or not
  bool running_;

 private:
  void Run();

  bool paint_while_stopped_;
  int frame_count_;  // How many frames we have.
  base::Time start_time_;  // Time when Start was called.
  SkBitmap* frames_;  // Frames bitmaps.
  base::TimeDelta frame_time_;  // How long one frame is displayed.
  base::RepeatingTimer<Throbber> timer_;  // Used to schedule Run calls.

  DISALLOW_COPY_AND_ASSIGN(Throbber);
};

// A SmoothedThrobber is a throbber that is representing potentially short
// and nonoverlapping bursts of work.  SmoothedThrobber ignores small
// pauses in the work stops and starts, and only starts its throbber after
// a small amount of work time has passed.
class VIEWS_EXPORT SmoothedThrobber : public Throbber {
 public:
  SmoothedThrobber(int frame_delay_ms);
  SmoothedThrobber(int frame_delay_ms, SkBitmap* frames);
  virtual ~SmoothedThrobber();

  virtual void Start();
  virtual void Stop();

  void set_start_delay_ms(int value) { start_delay_ms_ = value; }
  void set_stop_delay_ms(int value) { stop_delay_ms_ = value; }

 private:
  // Called when the startup-delay timer fires
  // This function starts the actual throbbing.
  void StartDelayOver();

  // Called when the shutdown-delay timer fires.
  // This function stops the actual throbbing.
  void StopDelayOver();

  // Delay after work starts before starting throbber, in milliseconds.
  int start_delay_ms_;

  // Delay after work stops before stopping, in milliseconds.
  int stop_delay_ms_;

  base::OneShotTimer<SmoothedThrobber> start_timer_;
  base::OneShotTimer<SmoothedThrobber> stop_timer_;

  DISALLOW_COPY_AND_ASSIGN(SmoothedThrobber);
};

// A CheckmarkThrobber is a special variant of throbber that has three states:
//   1. not yet completed (which paints nothing)
//   2. working (which paints the throbber animation)
//   3. completed (which paints a checkmark)
//
class VIEWS_EXPORT CheckmarkThrobber : public Throbber {
 public:
  CheckmarkThrobber();

  // If checked is true, the throbber stops spinning and displays a checkmark.
  // If checked is false, the throbber stops spinning and displays nothing.
  void SetChecked(bool checked);

  // Overridden from Throbber:
  virtual void OnPaint(gfx::Canvas* canvas);

 private:
  static const int kFrameTimeMs = 30;

  static void InitClass();

  // Whether or not we should display a checkmark.
  bool checked_;

  // The checkmark image.
  static SkBitmap* checkmark_;

  DISALLOW_COPY_AND_ASSIGN(CheckmarkThrobber);
};

}  // namespace views

#endif  // VIEWS_CONTROLS_THROBBER_H_