// top left
      case Gravity.TOP | Gravity.LEFT:
        path.moveTo(0.0f, 0.0f);
        path.lineTo(0.0f, (float) h);
        path.arcTo(new RectF(0.0f, 0.0f,
            ((float) w) * 2.0f, ((float) h) * 2.0f), 180.0f, 90.0f, true);
        path.lineTo((float) w, 0.0f);
        path.lineTo(0.0f, 0.0f);
        path.close();
        break;

  public void setCornerSize(int size){
    this.cornerSize = size;
    requestLayout();
    invalidate();
  }

   // window manager
    manager = (WindowManager) this.getApplicationContext()
        .getSystemService(Context.WINDOW_SERVICE);

    params = new WindowManager.LayoutParams();
    /*
     系统提示类型:7.0以前可以直接用TOAST的类型，不用申请权限，直接添加
     7.0以后不行了,需要申请SYSTEM_ALERT_WINDOW权限，window type最好
     设置为ERROR 或者 PHONE
     */
    if (Utilities.isCanUseToastType()) {
      params.type = WindowManager.LayoutParams.TYPE_TOAST;
    } else {
      params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ERROR;
    }
    params.format = 1;
    params.flags = WindowManager.LayoutParams.FLAG_FULLSCREEN // 全屏
        | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS // 覆盖到status bar
        | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION // 覆盖到导航栏

        // 以下属性设置加载我们圆角window 不抢焦点,不拦截事件
        | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
        | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
    params.alpha = 1.0f;
    params.x = 0;
    params.y = 0;
    // 设置 大小为全屏
    params.width = ViewUtil.getScreenSize(this).x;
    params.height = ViewUtil.getScreenSize(this).y;

  public void addCornerViewByPosition(String position){
    boolean enable = true;
    switch (position) {
      case LEFT_TOP:
        enable = leftTopEnable;
        params.gravity = Gravity.TOP | Gravity.LEFT;
        break;
      case RIGHT_TOP:
        enable = rightTopEnable;
        params.gravity = Gravity.TOP | Gravity.RIGHT;
        break;
      case LEFT_BOTTOM:
        enable = leftBottomEnable;
        params.gravity = Gravity.BOTTOM | Gravity.LEFT;
        break;
      case RIGHT_BOTTOM:
        enable = rightBottomEnable;
        params.gravity = Gravity.BOTTOM | Gravity.RIGHT;
        break;
    }
    CornerView corner = buildCorner(enable,params.gravity);
    if(!corners.containsValue(corner)) {
      corners.put(position, corner);
      manager.addView(corner, params);
    }
  }

private CornerView buildCorner(boolean enable,int position){
    CornerView corner = new CornerView(this);
    corner.setColor(currentColor);
    corner.setCornerOpacity(currentOpacity);
    corner.setCornerSize(currentCornerSize);
    corner.setLocation(position);
    if(enable){
      corner.show();
    } else {
      corner.hide();
    }
    return corner;
  }

 public static boolean checkFloatWindowPermission(Context context) {
    final int version = Build.VERSION.SDK_INT;
    if (version >= 19) {
      return checkOp(context, 24); //OP_SYSTEM_ALERT_WINDOW = 24;
    }
    return true;
  }

  @TargetApi(Build.VERSION_CODES.KITKAT)
  private static boolean checkOp(Context context, int op) {
    final int version = Build.VERSION.SDK_INT;
    if (version >= 19) {
      AppOpsManager manager = (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE);
      try {
        Class clazz = AppOpsManager.class;
        Method method = clazz.getDeclaredMethod("checkOp", int.class, int.class, String.class);
        return AppOpsManager.MODE_ALLOWED == (int)method.invoke(manager, op, Binder.getCallingUid(), context.getPackageName());
      } catch (Exception e) {
        Log.e("", Log.getStackTraceString(e));
      }
    } else {
      Log.e("Utilities", "Below API 19 cannot invoke!");
    }
    return false;
  }