onFling()手势不准确

Question

因此，我的onFling()方法具有以下主体：

    public boolean onFling(MotionEvent e1, MotionEvent e2,
                         float velocityX, float velocityY) {
      try {

        // Left swipe
        if ( velocityX < -SWIPE_THRESHOLD_VELOCITY) {
            if( velocityY < -SWIPE_THRESHOLD_VELOCITY) {
                GameWindow.writeToOutput("northwest");
                Log.d("Console","Wrote NW");
            }
            else
                GameWindow.writeToOutput("west");

            return true;
        // Right swipe
        } else if (velocityX > SWIPE_THRESHOLD_VELOCITY) {

            if( velocityY < -SWIPE_THRESHOLD_VELOCITY) {
                GameWindow.writeToOutput("northeast");
                Log.d("Console","Wrote NE");
            }
            else
                GameWindow.writeToOutput("east");

            return true;

        }

        if ( velocityY > SWIPE_THRESHOLD_VELOCITY) {

            GameWindow.writeToOutput("south");

            return true;
        }


        if ( velocityY < -SWIPE_THRESHOLD_VELOCITY) {

            GameWindow.writeToOutput("north");

            return true;
        }
      } catch (Exception e) {
        Log.e("YourActivity", "Error on gestures");
      }

      return false;
    }

我的问题是，我会做一个左上角的“放飞”，但速度会突然显示在logcat中，我在相反的方向上进行了“放飞”。这可能是模拟器的问题，还是我的代码没有准确地测量我的手势的方向？

Answer 1

好的，达特是对的，我想给他一点功劳。我修改了我的代码，以便更准确地测量手势，如果有人想使用这段代码，可以参考下面的代码。我将不得不稍微修改一下灵敏度，因为左上角的数字不会像上下角那样高，但这是一个非常可靠的起点。

    public boolean onFling(MotionEvent e1, MotionEvent e2,
                         float velocityX, float velocityY) {
      try {
          double xDir = e1.getX() - e2.getX();
          double yDir = e1.getY() - e2.getY();

          Log.d("Console","xVel = " + xDir);
          Log.d("Console","yVel = " + yDir);

        if ( xDir > SWIPE_THRESHOLD_VELOCITY) {
            if( yDir > SWIPE_THRESHOLD_VELOCITY) {
                //Up-Left swipe
                GameWindow.writeToOutput("northwest");
            }
            else  if ( yDir < -SWIPE_THRESHOLD_VELOCITY){
                //Down-Left swipe
                GameWindow.writeToOutput("southwest");
            }
            else{
                //Left swipe
                GameWindow.writeToOutput("west");
            }

            return true;
        } else if (xDir < -SWIPE_THRESHOLD_VELOCITY) {

            if( yDir > SWIPE_THRESHOLD_VELOCITY) {
                //Up-Right swipe
                GameWindow.writeToOutput("northeast");
            }else  if ( yDir < -SWIPE_THRESHOLD_VELOCITY){
                //Down-Right swipe
                GameWindow.writeToOutput("southeast");
            }
            else {
                //Right swipe
                GameWindow.writeToOutput("east");
            }

            return true;

        }

        if ( yDir < -SWIPE_THRESHOLD_VELOCITY) {
            //Down swipe
            GameWindow.writeToOutput("south");
            return true;
        }


        if ( yDir > SWIPE_THRESHOLD_VELOCITY) {
            //Up swipe
            GameWindow.writeToOutput("north");
            return true;
        }
      } catch (Exception e) {
        Log.e("YourActivity", "Error on gestures");
      }

      return false;
    }