private int startX , startY , endX, endY ;

private int screenWidth , screenHeight;

private int lastX, lastY ;

private DisplayMetrics dm;

獲取螢幕寬高
dm = getResources().getDisplayMetrics();

screenWidth = dm.widthPixels;
screenHeight = dm.heightPixels - getStatusBarHeight();

給控制元件設定ontouch事件

ziyou.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {

               switch (event.getAction()){

                   case MotionEvent.ACTION_DOWN:

                       lastX = (int) event.getRawX();// 獲取觸控事件觸控位置的原始X座標
                       lastY = (int) event.getRawY();
                       //記錄初始點選位置
                       startX = (int) event.getRawX();// 獲取觸控事件觸控位置的原始X座標
                       startY = (int) event.getRawY();

                       break;
                   case MotionEvent.ACTION_MOVE:

                        //移動距離
                       int dx = (int) event.getRawX() - lastX;
                       int dy = (int) event.getRawY() - lastY;
                       //移動後的上下左右
                       int l = v.getLeft() + dx;
                       int b = v.getBottom() + dy;
                       int r = v.getRight() + dx;
                       int t = v.getTop() + dy;
                       // 下面判斷移動是否超出螢幕
                       if (l < 0) {
                           l = 0;
                           r = l + v.getWidth();
                       }
                       if (t < 0) {
                           t = 0;
                           b = t + v.getHeight();
                       }
                       if (r > screenWidth) {
                           r = screenWidth;
                           l = r - v.getWidth();
                       }
                       if (b > screenHeight) {
                           b = screenHeight;
                           t = b - v.getHeight();
                       }
                       v.layout(l, t, r, b);
                       lastX = (int) event.getRawX();
                       lastY = (int) event.getRawY();
                       v.postInvalidate();

                       break;
                   case MotionEvent.ACTION_UP:

                       //記錄結束點選位置
                       endX = (int) event.getRawX();
                       endY = (int) event.getRawY();
                       
                       if (endX == startX && endY == startY) {

                           ToastUtil.showToast(MainActivity.this,"點選了靈活按鍵");
                       }
                       break;
                   default:
                       break;
               }
               return true;
            }
        });