Android實現拖動效果的兩種方法

2019-10-22 18:12:23

字體：大中小

來源：轉載

供稿：網友

因為最近項目的需要，需要實現一個拖動效果，看了一下網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，還有很多復雜的事件，發現會有很奇怪的效果，抖動很厲害，而且時不時回到原來的位置，后來發現這個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：

Android,拖動