Android實現(xiàn)拖動效果的兩種方法

更新時間：2018年04月26日 15:49:02 作者：u013772458

這篇文章主要為大家詳細介紹了Android實現(xiàn)拖動效果的兩種方法，具有一定的參考價值，感興趣的小伙伴們可以參考一下

因為最近項目的需要，需要實現(xiàn)一個拖動效果，看了一下網(wǎng)上剛好有這種拖動效果的demo,代碼大概如下：

private void initListener(){
    screenWidth = getScreenWidth(this);//獲取屏幕寬度
    screenHeight = getScreenHeight(this) - getStatusHeight(MainActivity.this);//屏幕高度-狀態(tài)欄
    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;//這里根據(jù)項目需要選擇false與true
      }
    });
  }

可是我的項目本身是有涂鴉的界面，還有很多復(fù)雜的事件，發(fā)現(xiàn)會有很奇怪的效果，抖動很厲害，而且時不時回到原來的位置，后來發(fā)現(xiàn)這個v.layout(left, top, left+v.getWidth(), top+v.getHeight());可能不適合項目的需求，所以我想了另一種解法。代碼如下：

 private void initListener(){
    screenWidth = getScreenWidth(this);//獲取屏幕寬度
    screenHeight = getScreenHeight(this) - getStatusHeight(MainActivity.this);//屏幕高度-狀態(tài)欄
    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;
            }

            RelativeLayout.LayoutParams param = new RelativeLayout.LayoutParams(v.getWidth(), v.getHeight());
            param.leftMargin = left;
            param.topMargin = top;
            v.setLayoutParams(param);
//            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;
      }
    });
  }

效果如下圖：