/** Created by xuzhilei on 2016/8/16. 模仿音乐暂停开始按钮的View */
public class PlayButtonView extends View {
 
 /** 中心点X轴坐标 */
 private int viewCenterX;
 
 /** 中心点Y轴坐标 */
 private int viewCenterY;
 
 /** 有效长度的一般（View长宽较小者的一半） */
 private int viewHalfLength;
 
 /** 三角形右侧顶点 */
 private Point pointA = new Point();
 
 /** 三角形左上顶点 */
 private Point pointB = new Point();
 
 /** 三角形左下顶点 */
 private Point pointC = new Point();
 
 /** 矩形左边界 */
 private int RectLeft;
 
 /** 矩形上边界 */
 private int RectTOP;
 
 /** 矩形右边界 */
 private int RectRight;
 
 /** 矩形下边界 */
 private int RectBottom;
 
 /** 三角形的三条边路径 */
 private Path path = new Path();
 
 /** 包围最外侧圆环的矩形 */
 private RectF rectF = new RectF();
 
 /** 包围进度圆弧的矩形 */
 private RectF rectF2 = new RectF();
 
 /** 进度 */
 private int progress;
 
 /** 暂停中还是播放中 */
 private boolean isPlaying = false;
 
 /** 是否进行过了测量 */
 private boolean isMeasured = false;
 
 /** 画笔颜色 */
 private int color = 0xffff0099;
 
 /** 最外侧圆环画笔 */
 private Paint paintA = new Paint();
 
 /** 进度圆弧画笔 */
 private Paint paintB = new Paint();
 
 /** 暂停开始画笔 */
 private Paint paintC = new Paint();
 
 /** 状态监听器 */
 private OnStatusChangeListener onStatusChangeListener;
 
 /** 构造器 */
 public PlayButtonView(Context context, AttributeSet attrs) {
 super(context, attrs);
 }
 
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 if (!isMeasured) {
  getWidthAndHeight();
  isMeasured = true;
 }
 }
 
 /** 得到视图等的高度宽度尺寸数据 */
 private void getWidthAndHeight() {
 
 int viewHeight = getMeasuredHeight();
 int viewWidth = getMeasuredWidth();
 viewCenterX = viewWidth / 2;
 viewCenterY = viewHeight / 2;
 viewHalfLength = viewHeight < viewWidth ? viewHeight / 2 : viewWidth / 2;
 
 int paintAwidth = viewHalfLength / 15;
 int paintBwidth = viewHalfLength / 8;
 
 rectF.left = viewCenterX - (viewHalfLength - paintAwidth / 2);
 rectF.top = viewCenterY - (viewHalfLength - paintAwidth / 2);
 rectF.right = viewCenterX + (viewHalfLength - paintAwidth / 2);
 rectF.bottom = viewCenterY + (viewHalfLength - paintAwidth / 2);
 
 rectF2.left = viewCenterX - (viewHalfLength - paintBwidth / 2);
 rectF2.top = viewCenterY - (viewHalfLength - paintBwidth / 2);
 rectF2.right = viewCenterX + (viewHalfLength - paintBwidth / 2);
 rectF2.bottom = viewCenterY + (viewHalfLength - paintBwidth / 2);
 
 paintA.setColor(color);
 paintA.setStrokeWidth(paintAwidth);
 paintA.setAntiAlias(true);
 paintA.setStyle(Paint.Style.STROKE);
 
 paintB.setColor(color);
 paintB.setStrokeWidth(paintBwidth);
 paintB.setAntiAlias(true);
 paintB.setStyle(Paint.Style.STROKE);
 
 paintC.setColor(color);
 paintC.setStrokeWidth(1);
 paintC.setAntiAlias(true);
 paintC.setStyle(Paint.Style.FILL);
 
 pointA.x = viewCenterX + viewHalfLength / 2;
 pointA.y = viewCenterY;
 
 double sin = Math.sin(Math.toRadians(60)); // √(3) / 2
 double cos = Math.cos(Math.toRadians(60)); // 1/ 2
 
 pointB.x = (float) ((viewCenterX - cos * viewHalfLength + viewCenterX) / 2);
 pointB.y = (float) ((viewCenterY - sin * viewHalfLength + viewCenterY) / 2);
 
 pointC.x = (float) ((viewCenterX - cos * viewHalfLength + viewCenterX) / 2);
 pointC.y = (float) ((viewCenterY + sin * viewHalfLength + viewCenterY) / 2);
 
 RectLeft = viewCenterX - viewHalfLength / 3;
 RectTOP = viewCenterY - viewHalfLength / 3;
 RectRight = viewCenterX + viewHalfLength / 3;
 RectBottom = viewCenterY + viewHalfLength / 3;
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 
 // 画未完成进度的圆环
 canvas.drawArc(rectF, 0, 360, false, paintA);
 
 // 画已经完成进度的圆弧 从-90度开始，即从圆环顶部开始
 canvas.drawArc(rectF2, -90, progress * 3.6f, false, paintB);
 
 if (isPlaying) {
  canvas.drawRect(RectLeft, RectTOP, RectRight, RectBottom, paintC);
 } else {
  path.reset();
  path.moveTo(pointA.x, pointA.y);
  path.lineTo(pointB.x, pointB.y);
  path.lineTo(pointC.x, pointC.y);
  path.close();
  canvas.drawPath(path, paintC);
 }
 }
 
 /** 监听触摸DOWN时间，开始播放，暂停播放 */
 @Override
 public boolean onTouchEvent(MotionEvent event) {
 
 if (event.getAction() == MotionEvent.ACTION_DOWN) {
  isPlaying = !isPlaying;
  invalidate();
  if (isPlaying) {
  onStatusChangeListener.play();
  } else {
  onStatusChangeListener.pause();
  }
 }
 return super.onTouchEvent(event);
 }
 
 /** 设置进度 0-100区间 */
 public void setProgress(int progress) {
 
 if (progress < 0) {
  progress = 0;
 }
 if (progress > 100) {
  progress = 100;
 }
 this.progress = progress;
 invalidate();
 }
 
 /** 外界设置播放状态 */
 public void setPlaying(boolean isPlaying) {
 this.isPlaying = isPlaying;
 invalidate();
 }
 
 /** 播放暂停状态监听的接口 */
 public interface OnStatusChangeListener {
 
 void play();
 
 void pause();
 }
 
 /** 设置监听接口 */
 public void setOnStatusChangeListener(OnStatusChangeListener onStatusChangeListener) {
 this.onStatusChangeListener = onStatusChangeListener;
 }
 
 /** 位置信息 */
 private class Point {
 float x;
 float y;
 }