Android View拖拽跟随手指移动

package test.view;

import android.content.Context;
import android.os.Build;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;

import com.zhisheng.test.R;

/**
 * 实现功能根据手指滑动
 */
public class MyView extends View {
    int x1=0, x2=0, y1=0, y2=0;
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public MyView(Context context) {
        super(context);
        init(context);
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public MyView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    void init(Context context) {
      
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        onMyTouch(event);
        return true;
    }

    void onMyTouch(MotionEvent event) {


        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                y1 = (int)event.getY();
                x1 = (int)event.getX();
                break;
            case MotionEvent.ACTION_MOVE:
                x2 = (int)event.getX();
                y2 = (int)event.getY();
                layout(x2-x1+getLeft(), y2-y1+getTop(), x2-x1+getRight(), y2-y1+getBottom());
                break;
        }
    }

}