Android开发中使用View实现咻一咻效果

public class ClickCircleView extends View { private Bitmap bitmap; private Paint paint; private Canvas canvas; private boolean isSpreadFlag = false;//标记是否发射完成 public boolean isSpreadFlag() {  return isSpreadFlag; } public void setIsSpreadFlag(boolean isSpreadFlag) {  this.isSpreadFlag = isSpreadFlag; } public ClickCircleView(Context context, int width, int height, int screenWidth, int screenHeight) {  super(context);  bitmap = Bitmap.createBitmap(screenWidth, screenHeight, Bitmap.Config.ARGB_8888); // 设置位图的宽高  canvas = new Canvas();  canvas.setBitmap(bitmap);  paint = new Paint(Paint.DITHER_FLAG);  paint.setAntiAlias(true);  paint.setColor(Color.WHITE);  paint.setStyle(Paint.Style.FILL);  paint.setAlpha(50);  canvas.drawCircle(screenWidth / 2, screenHeight / 2, width / 2 + 10, paint);  invalidate(); } @Override protected void onDraw(Canvas canvas) {  canvas.drawBitmap(bitmap, 0, 0, null); }}