Android 修改系统关机动画的实现

private static void beginShutdownSequence(Context context) {
  ...... 3   // throw up an indeterminate system dialog to indicate radio is
  // shutting down.
  //*********************** 系统默认的Dialog  ***********************
  /*ProgressDialog pd = new ProgressDialog(context);
  pd.setTitle(context.getText(com.android.internal.R.string.power_off));
  pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
  pd.setIndeterminate(true);
  pd.setCancelable(false);
  pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
  pd.show();*/
  //*********************** 替换为自定义的全屏Dialog  ***********************
  Point outSize = new Point();
  Dialog dialog = new Dialog(context, android.R.style.Theme_Black_NoTitleBar_Fullscreen);
  IndeterminateProgressBar view = new IndeterminateProgressBar(context);
  dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
  dialog.getWindow().getWindowManager().getDefaultDisplay().getSize(outSize); //获取屏幕宽高
  dialog.setContentView(view, new LayoutParams(outSize.x, outSize.y));     //设置自定义view宽高为全屏
  dialog.show();
  
  ......
}

class IndeterminateProgressBar extends View {
  static final String TAG = "ProgressBar";
  private int delayMillis = 30;
  private Handler mHandler;
  private ArrayList<Entity> entities;
  private int width = 0;
  // private int height = 0;
  private int r = 15;
  private int shift = 20;
  private int radius = 3;
  private int color = Color.WHITE;
  private long time = 0;
  private boolean started = false;
  public IndeterminateProgressBar(Context context) {
    super(context);
    init();
  }
  @Override
  protected void onLayout(boolean changed, int left, int top, int right,
      int bottom) {
    super.onLayout(changed, left, top, right, bottom);
    width = getLayoutParams().width / 2;
    // height = getLayoutParams().height;
    if (width > 0) {
      radius = width / 20;
      r = 2 * width / 5;
      //shift = width / 2;
      shift = width / 1;
    }
  }
  private void init() {
    setBackgroundResource(android.R.color.transparent);
    mHandler = new Handler(new Handler.Callback() {
      @Override
      public boolean handleMessage(Message msg) {
        for (Entity e : entities) {
          e.update();
        }
        invalidate();
        mHandler.sendEmptyMessageDelayed(0, delayMillis);
        time += delayMillis;
        return false;
      }
    });
  }
  public void setColor(int color) {
    this.color = color;
  }
  public void stop() {
    mHandler.removeMessages(0);
    started = false;
    invalidate();
  }
  public boolean isStart() {
    return started;
  }
  public void start() {
    if (started)
      return;
    started = true;
    time = 0;
    entities = new ArrayList<IndeterminateProgressBar.Entity>();
    float s = .25f;
    entities.add(new Entity(0, color, 0));
    entities.add(new Entity(1 * s, color, delayMillis * 4));
    entities.add(new Entity(2 * s, color, delayMillis * 8));
    entities.add(new Entity(3 * s, color, delayMillis * 12));
    entities.add(new Entity(4 * s, color, delayMillis * 16));
    // entities.add(new Entity(5 * s, color, delayMillis * 20));
      if (mHandler != null)
        mHandler.sendEmptyMessage(0);
    }
    @Override
    protected void onDraw(Canvas canvas) {
      if (entities != null && entities.size() > 0) {
        for (Entity e : entities) {
          e.draw(canvas);
        }
      }
      super.onDraw(canvas);
    }
    class Entity {
      private float x;
      private float y;
      private int color;
      private Paint paint;
      private double sp = 0;
      private long delay;
      private int sec = 0;
      private float pec = 0;
      boolean visiable = true;
      public float getInterpolation(float input) {
        return (float) (Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
      }
      public Entity(float sp, int color, int delay) {
        paint = new Paint();
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.FILL);
        this.color = color;
        this.sp = sp;
        this.delay = delay;
        paint.setColor(this.color);
      }
      public void update() {
        if (time < delay)
          return;
        visiable = true;
        pec += 0.03;
        if (pec > 1) {
          pec = 0;
          sec = ++sec == 3 ? 0 : sec;
          delay = sec == 0 ? time + delayMillis * 22 : time + delayMillis
              * 3;
          visiable = sec == 0 ? false : true;
        }
        double θ = Math.PI
            * .5
            + (sec == 0 ? 0 : sec * Math.PI / sec)
            - (sec == 0 ? 0 : sp)
            + (Math.PI * (sec == 1 ? 2 : 1) - (sec == 0 ? sp : 0) + (sec == 2 ? sp
                : 0)) * getInterpolation(pec);
        x = (float) (r / 2 * Math.cos(θ)) + shift / 2;
        y = (float) (r / 2 * Math.sin(θ)) + shift / 2;
      }
      public void draw(Canvas canvas) {
        if (!visiable || x == 0 || y == 0)
          return;
        canvas.save();
        canvas.translate(x, y);
        canvas.drawCircle(x, y, radius, paint);
        canvas.restore();
      }
    }
    @Override
    protected void onAttachedToWindow() {
      super.onAttachedToWindow();
      if (getVisibility() == View.VISIBLE) {
        start();
      }
    }
    @Override
    protected void onDetachedFromWindow() {
      super.onDetachedFromWindow();
      stop();
    }
    public void setDelayMillis(int delayMillis) {
      this.delayMillis = delayMillis;
    }
}