【Android游戏开发十九】(必看篇)SurfaceView运行机制详解
切入后台操作比如点击HOME按键，点击返回按键...
那么重新进入程序报异常主要Surfaceiew 有两点会报异常：
第一：提交画布异常！如下图(模拟器错误提示，以及Logcat Detail)
解决代码：
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public void draw() {
try {
canvas = sfh.lockCanvas();
if (canvas != null) {
canvas.drawColor(Color.WHITE);
canvas.drawBitmap(bmp, bmp_x, bmp_y, paint);
}
} catch (Exception e) {
Log.v("Himi", "draw is Error!");
} finally {//备注1
if (canvas != null)//备注2
sfh.unlockCanvasAndPost(canvas);
}
}
先看备注1这里，之前的文章中我给大家解释过为什么要把sfh.unlockCanvasAndPost(canvas); 写在finally中，主要是为了保证能正常的提交画
布.今天主要说说备注2，这里一定要判定下canvas是否为空，因为当程序切入后台的时候，canvas是获取不到的！那么canvas一旦为空，提交画
布这里就会出现参数异常的错误！
下面来说另外一种情况：线程启动异常!如下图(模拟器错误提示，以及Logcat Detail)
这种异常只是在当你程序运行期间点击Home按钮后再次进入程序的时候报的异常,异常说咱们的线程已经启动！为什么返回按钮就没事？
OK，下面我们就要来先详细讲解一下Android中Back和Home按键的机制！然后分析问题，并且解决问题！
先看下面MySurfaceViewAnimation.java的类中的代码:
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public class MySurfaceViewAnimation extends SurfaceView implements Callback, Runnable {
private Thread th;
private SurfaceHolder sfh;
private Canvas canvas;
private Paint paint;
private Bitmap bmp;
private int bmp_x, bmp_y;
public MySurfaceViewAnimation(Context context) {
super(context);
this.setKeepScreenOn(true);
bmp = BitmapFactory.decodeResource(getResources(), R.drawable.himi_dream);
sfh = this.getHolder();
sfh.addCallback
补充：移动开发 , Android ,
