Android View 跟隨手指移動 最簡單實現方法

話不多說，上代碼：

package com.test.movemyview;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.RelativeLayout;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        RelativeLayout rl = new RelativeLayout(this);

        final ImageView iv = new ImageView(this);
        iv.setImageResource(R.mipmap.ic_launcher);
        RelativeLayout.LayoutParams ivlp = new RelativeLayout.LayoutParams(500, 500);
        ivlp.addRule(RelativeLayout.CENTER_IN_PARENT);
        ivlp.setMargins(100,10,50,200);
        iv.setLayoutParams(ivlp);

        iv.setOnTouchListener(new View.OnTouchListener() {
            private float downX;
            private float downY;

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        //按下位置
                        downX = event.getRawX();
                        downY = event.getRawY();

                        break;
                    case MotionEvent.ACTION_MOVE:

                        float moveX = event.getRawX();
                        float moveY = event.getRawY();

                        float dx = moveX - downX;
                        float dy = moveY - downY;

                        float tX = v.getTranslationX() + dx;
                        float tY = v.getTranslationY() + dy;

                        v.setTranslationX(tX);
                        v.setTranslationY(tY);

                        // 下一次按下位置
                        downX = event.getRawX();
                        downY = event.getRawY();
                        break;
                    case MotionEvent.ACTION_UP:

                        //復位
//                        v.setTranslationX(0);
//                        v.setTranslationY(0);
                        break;
                }

                return true;

            }
        });

        rl.addView(iv);
        setContentView(rl);
    }
    
}