surfaceview 刷新bitmap

要在 SurfaceView 中刷新 Bitmap，你需要在 SurfaceView 中创建一个绘制线程，然后在该线程中使用 Canvas 绘制 Bitmap。具体步骤如下：

1. 在 SurfaceView 中创建一个绘制线程：

class DrawThread extends Thread {
    private SurfaceHolder surfaceHolder;
    private boolean isRunning;
    private Bitmap bitmap;

    public DrawThread(SurfaceHolder surfaceHolder, Bitmap bitmap) {
        this.surfaceHolder = surfaceHolder;
        this.bitmap = bitmap;
        isRunning = true;
    }

    public void setRunning(boolean running) {
        isRunning = running;
    }

    @Override
    public void run() {
        while (isRunning) {
            Canvas canvas = null;
            try {
                canvas = surfaceHolder.lockCanvas();
                if (canvas != null) {
                    canvas.drawBitmap(bitmap, 0, 0, null);
                }
            } finally {
                if (canvas != null) {
                    surfaceHolder.unlockCanvasAndPost(canvas);
                }
            }
        }
    }
}

2. 在 SurfaceView 中创建一个 SurfaceHolder.Callback 对象，实现 surfaceCreated() 方法，在该方法中启动绘制线程：

class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback {
    private DrawThread drawThread;
    private Bitmap bitmap;

    public MySurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        getHolder().addCallback(this);
        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.my_bitmap);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        drawThread = new DrawThread(holder, bitmap);
        drawThread.start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        boolean retry = true;
        drawThread.setRunning(false);
        while (retry) {
            try {
                drawThread.join();
                retry = false;
            } catch (InterruptedException e) {
            }
        }
    }
}

这样，每当你更新 Bitmap 的时候，就可以在绘制线程中重新绘制 Bitmap，从而实现 SurfaceView 中 Bitmap 的刷新。