Android实现拖动效果的两种方法-创新互联

因为最近项目的需要，需要实现一个拖动效果，看了一下网上刚好有这种拖动效果的demo,代码大概如下：

private void initListener(){
    screenWidth = getScreenWidth(this);//获取屏幕宽度
    screenHeight = getScreenHeight(this) - getStatusHeight(MainActivity.this);//屏幕高度-状态栏
    testTv.setOnTouchListener(new View.OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {

          case MotionEvent.ACTION_DOWN:
            lastX = (int) event.getRawX();
            lastY = (int) event.getRawY();
            break;

          case MotionEvent.ACTION_MOVE:
            int dx = (int) event.getRawX() - lastX;
            int dy = (int) event.getRawY() - lastY;

            int top = v.getTop() + dy;


            int left = v.getLeft() + dx;


            if (top <= 0) {
              top = 0;
            }
            if (top >= screenHeight - testTv.getHeight() ) {
              top = screenHeight - testTv.getHeight();
            }
            if (left >= screenWidth - testTv.getWidth()) {
              left = screenWidth - testTv.getWidth();
            }

            if (left <= 0) {
              left = 0;
            }


            v.layout(left, top, left+v.getWidth(), top+v.getHeight());

            v.postInvalidate();

            lastX = (int) event.getRawX();
            lastY = (int) event.getRawY();

        break;
        case MotionEvent.ACTION_UP:
        break;

        }
        return true;//这里根据项目需要选择false与true
      }
    });
  }