android游戏开发5-5 实现背景图的沿x轴移动

package com.mz.demo;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.view.SurfaceHolder;import android.view.SurfaceHolder.Callback;import android.view.SurfaceView;public class MySurfaceView extends SurfaceView implements Callback, Runnable {    // 1.声明变量、对象    private Paint paint;    private Canvas canvas;    private SurfaceHolder sfh;    private Bitmap map1, map2;    private int x = 0;    private int y = 0;    private int x2 = 0;    private boolean isDo = true;    private Thread thread;    public MySurfaceView(Context context) {        super(context);        paint = new Paint();        paint.setAntiAlias(true);        sfh = this.getHolder();        sfh.addCallback(this);        map1 = BitmapFactory.decodeResource(getResources(),                R.drawable.background);        map2 = BitmapFactory.decodeResource(getResources(), R.drawable.water);        // TODO Auto-generated constructor stub    }    public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {        // TODO Auto-generated method stub    }    public void surfaceCreated(SurfaceHolder holder) {        // TODO Auto-generated method stub        x = this.getWidth() - map2.getWidth();// 注1        y = this.getHeight() - map2.getHeight();        x2 = x - map2.getWidth();        // Mydraw();        thread = new Thread(this);//***这里要注意因为采用的是继承接口的方式，所以要在括号里些写this 总感觉期末可能作为改错题        thread.start();    }    private void Mydraw() {        // TODO Auto-generated method stub        canvas = sfh.lockCanvas();//锁定画布        canvas.drawColor(Color.WHITE);        canvas.drawBitmap(map2, x, y, paint);        canvas.drawBitmap(map2, x2, y, paint);        sfh.unlockCanvasAndPost(canvas);//解锁    }    public void surfaceDestroyed(SurfaceHolder holder) {        // TODO Auto-generated method stub    }    public void run() {        // TODO Auto-generated method stub        while (isDo) {            Mydraw();            logic();            try {                Thread.sleep(100);            } catch (Exception e) {                e.printStackTrace();                // TODO: handle exception            }        }    }    private void logic() {        // TODO Auto-generated method stub        if(x>=this.getWidth()){            x=this.getWidth() - map2.getWidth()-map2.getWidth()+1;//+1的作用是去点两个图pain连接处的间隙        }else{            x+=5;        }        if(x2>=this.getWidth()){            x2=this.getWidth() - map2.getWidth()-map2.getWidth()+1;        }else{            x2+=5;        }    }}

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