android 在surfaceView上画图
16lz
2021-01-26
为了在SurfaceView上画图,我们定义一个MySurfaceView类,该类继承SurfaceView并且实现SurfaceHolder.Callback接口。在surfaceCreated方法中我们启动一个线程,在该线程中实现对画布canvas的操作。
import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.view.SurfaceHolder;import android.view.SurfaceHolder.Callback;import android.view.SurfaceView;/** * * @author xu duzhou * */public class Mysurfaceview extends SurfaceView implements Callback { SurfaceHolder holder; MysurfaceviewThread mysurfaceviewThread; public Mysurfaceview(Context context) { super(context); // TODO Auto-generated constructor stub holder = getHolder();//获取SurfaceHolder对象,同时指定callback holder.addCallback(this); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { // 当SurfaceView被创建时,将画图Thread启动起来。 mysurfaceviewThread = new MysurfaceviewThread(); mysurfaceviewThread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // 当SurfaceView被销毁时,释放资源。 if (mysurfaceviewThread != null) { mysurfaceviewThread.exit(); mysurfaceviewThread = null; } } /** * 内部类 MysurfaceviewThread,该类主要实现对canvas的具体操作。 * @author xu duzhou * */ class MysurfaceviewThread extends Thread { private boolean done = false; public MysurfaceviewThread() { super(); this.done = false; } public void exit() { // 将done设置为true 使线程中的while循环结束。 done = true; try { join(); } catch (Exception e) { // TODO: handle exception } } @Override public void run() { // TODO Auto-generated method stub super.run(); SurfaceHolder surfaceHolder = holder; int i = 1; int j = 0; while (!done) { if (i > j) { j = i; i++; } else { j = i; i--; } synchronized (surfaceHolder) { //锁定canvas Canvas canvas = surfaceHolder.lockCanvas(); //canvas 执行一系列画的动作 canvas.drawColor(Color.BLACK); Bitmap _bit = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher); canvas.drawBitmap(_bit, 10 + i, 10 + i, null);//使用默认的Paint对象 //释放canvas对象,并发送到SurfaceView surfaceHolder.unlockCanvasAndPost(canvas); } if (i == 100) { j = i; } if (i == 1) { j = 0; } } } }}
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new Mysurfaceview(this)); }
程序运行结果就是 图片来回的运动如下图:
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