Android跟随手指移动的控件demo实例

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@mipmap/pic1"
    android:id="@+id/horse"
    tools:context=".MainActivity">

package com.xiaozeng.demo;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.View;

public class HorseDemo extends View {
    //设置两个变量
    public float horseX,horseY;
//创建构造方法
    public HorseDemo(Context context) {
        super(context);
        horseX = 200;
        horseY = 300;
    }
    //第二步：重写onDraw方法 Ctrl+o

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //实例化画图对象
        Paint paint = new Paint();
        //位图对象
        Bitmap bitmap = BitmapFactory.decodeResource(this.getResources(),R.mipmap.pic2);
       //回收
        canvas.drawBitmap(bitmap,horseX,horseY,paint);
        if(bitmap.isRecycled()){
            bitmap.recycle();

        }
    }
}

package com.xiaozeng.demo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ViewAnimator;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取布局管理器
        FrameLayout frameLayout = findViewById(R.id.horse);
        //实例化
        HorseDemo horseDemo = new HorseDemo(this);
        //触摸事件监听器
        horseDemo.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                //坐标
                horseDemo.horseX = event.getX();
                horseDemo.horseY = event.getY();
                //重绘
                horseDemo.invalidate();

                return true;
            }
        });
        frameLayout.addView(horseDemo);
    }
}