Question

这是我的代码：

public boolean onTouch(View v, MotionEvent event) {

    switch(event.getActionMasked()) {

    case MotionEvent.ACTION_DOWN:
        Log.d("getButtonCode", "catch ACTION_DOWN");
        break;
    case MotionEvent.ACTION_POINTER_DOWN:
        Log.d("getButtonCode", "catch ACTION_POINTER_DOWN");
        break;
    case MotionEvent.ACTION_POINTER_UP:
        Log.d("getButtonCode", "catch ACTION_POINTER_UP");
        break;
    case MotionEvent.ACTION_UP:
        Log.d("getButtonCode", "catch ACTION_UP");
    case MotionEvent.ACTION_CANCEL:
        Log.d("getButtonCode", "catch ACTION_CANCEL");
    case MotionEvent.ACTION_MOVE:
        break;
    default:
        break;
    }
    return true;
}

我从未捕获过ACTION_POINTER_DOWN和ACTION_POINTER_UP。如果我从ACTION_DOWN中删除break，我总是在ACTION_DOWN之后捕获ACTION_POINTER_DOWN，即使它是第一个指针。我认为应该如此：第一个指针只捕获ACTION_DOWN，每个下一个指针只有ACTION_POINTER_DOWN，如果非主指针已经上升，我应该捕获ACTION_POINTER_UP。

但它不起作用。我的代码出了什么问题？

PS：我看到了其他类似的问题，但没有回答帮助我。

Answer 1

我没有使用switch语句，而是使用了一系列if语句。这让我可以对event.getAction（）或event.getActionMasked（）进行测试，它允许同时执行多个可能的操作。

public boolean onTouch(View v, MotionEvent event) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                startingX = (int) event.getX();
                startingY = (int) event.getY();
            }
            if(event.getAction() == MotionEvent.ACTION_MOVE) {
                int scaleX = 1;
                int scaleY = 1;
                if(touchStateScale == true){
                    scaleX = (int) (event.getX(0) - event.getX(1));
                    scaleY = (int) (event.getY(0) - event.getY(1));
                }
                int endingX = (int) event.getX();
                int endingY = (int) event.getY();

                int newX = endingX-startingX;
                int newY = endingY-startingY;


            ((ImageView) v).setImageBitmap(drawNewImageScaled(baseImage, newImageResourceId, newX, newY, scaleX, scaleY));
            }
            if(event.getActionMasked() == MotionEvent.ACTION_POINTER_DOWN){
                Log.i(TAG, "second pointer detected");
                touchStateScale = true;
            }
            if (event.getAction() == MotionEvent.ACTION_UP) {
                touchStateScale = false;
                return false;
            }
            return true;
        }
    };

Android多点触控：没有ACTION_POINTER_DOWN和UP事件

1 个答案: