Android 自定义可拖拽View，界面渲染刷新后不会自动回到起始位置

来源：互联网发布：电吉他知乎编辑：程序博客网时间：2024/05/19 08:44
以自定义ImageView为例：
/** * 可拖拽ImageView * Created by admin on 2017/2/21. */public class FloatingImageView extends ImageView{    public FloatingImageView(Context context) {        super(context);    }    public FloatingImageView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public FloatingImageView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    @TargetApi(Build.VERSION_CODES.LOLLIPOP)    public FloatingImageView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {        super(context, attrs, defStyleAttr, defStyleRes);    }        int startX;    int startY;    int left;    int top;    int[] temp = new int[]{ 0, 0 };    @Override    public boolean onTouchEvent(MotionEvent event) {        boolean isMove = false;        int x = (int) event.getRawX();        int y = (int) event.getRawY();        switch (event.getAction()){            case MotionEvent.ACTION_DOWN: // touch down so check if the                startX = x;                startY = y;                temp[0] = (int) event.getX();                temp[1] = y - getTop();                break;            case MotionEvent.ACTION_MOVE: // touch drag with the ball                left = x - temp[0];                top = y - temp[1];                if(left < 0){//控制左边界不超出                    left = 0;                }                layout(left, top, left + getWidth(),top + getHeight());//自由拖拽                break;            case MotionEvent.ACTION_UP:                if (Math.abs(x - startX) > 2 || Math.abs(y - startY) > 2){//判断是否移动,再一定范围内不算是移动，解决触发事件冲突                    //将最后拖拽的位置定下来，否则页面刷新渲染后按钮会自动回到初始位置                    //注意父容器                    RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) getLayoutParams();                    lp.setMargins(left, top,0,0);                    setLayoutParams(lp);                    //确定是拖拽                    isMove = true;                 }                break;        }        return isMove ? true : super.onTouchEvent(event);     }}
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