我一直在尝试在Observer回调中进行绘制,当我尝试锁定画布时,我总是得到一个null返回 . SurfaceHolder似乎没问题 . 我添加了一个SurfaceHolder回调,它在游戏的早期就被调用了 .
这是我的Observer更新方法:
// implements Observer
public void update(Observable observable, Object data) {
Canvas c = null;
Log.i(TAG, "Surface Observer of CbSurfaceState thread: "
+ Thread.currentThread().getName());
try {
synchronized(mCbHolder) {
c = mCbHolder.lockCanvas(null);
if(c == null) {
Log.i(TAG, "lockCanvas returned null");
} else {
doDraw(c);
}
}
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (c != null) {
mCbHolder.unlockCanvasAndPost(c);
}
}
}
这是我在初始化中首次使用它的地方:
public void initCbSurfaceView(Context context) {
mContext = context;
// register our interest in hearing about changes to our surface
mCbHolder = getHolder();
Log.i(TAG,"got holder");
mCbHolder.addCallback(cbSurfaceHolderCallback);
Log.i(TAG,"added callback");
// initially in preview mode
mCbHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
// previewHolder.(SurfaceHolder); Don't know how to replace, but it
// won't work without the above.
...
mCbSurfaceState.addObserver(this);
Log.i(TAG, "Creation of CbSurfaceState thread: "
+ Thread.currentThread().getName());
}
我甚至在创建曲面时再次设置它(我最近添加它只是为了确定)
SurfaceHolder.Callback cbSurfaceHolderCallback = new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.i(TAG, "In surfaceCreated callback");
mCbHolder = holder;
}
...
};
这是一些日志 . 我打印了线程,因为起初它是从Asynch线程开始的,我设法避免这个:
02-24 20:31:10.380: I/CbSurfaceView(4013): In surfaceCreated callback
02-24 20:31:10.380: I/CbSurfaceView(4013): SurfaceChanged 854X404
02-24 20:31:10.380: I/CbSurfaceView(4013): initPreview width 854 height 404
...
02-24 20:31:25.974: I/CbTouchListener(4013): onTouch Down x 665.7714 y 194.92023
02-24 20:31:25.974: I/CbSurfaceView(4013): Surface Observer of CbSurfaceState thread: main
02-24 20:31:25.981: I/CbSurfaceView(4013): lockCanvas returned null
02-24 20:31:26.005: I/CbSurfaceView(4013): Surface Observer of CbSurfaceState thread: main
02-24 20:31:26.075: I/CbSurfaceView(4013): lockCanvas returned null
世界上我做错了什么?我的doDraw一直在努力,直到它试图绘制位图 . 然后我想从lockCanvas检查null .
我在这里找到了答案How to draw an overlay on a SurfaceView used by Camera on Android?看来你无法在预览上画画 . 我得到了关于PUSH_BUFFER类型表面的异常,因此我将其重置为NORMAL以便它不会抱怨 . 我无法锁定预览的表面,如果它不是NORMAL,它将抛出异常 . 显然,您无法动态更改曲面类型 . 这可能是它被弃用的原因,但除非您将其设置为PUSH_BUFFER,否则相机预览将无法工作 . 我将在顶部添加另一个非Surface视图,用于绘制和渲染拍摄的照片 .
谢谢你的期待,我希望这有助于某人 .