Android Camera开发:扫描二维码,周期性循环自动聚焦auto focus挂掉原因分析(preview is not enabled)

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发布时间：2013-12-09 23:23:51

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问题背景：要让Camera循环聚焦，聚焦完成后进行拍照，在拍照的数据里截取出一定区域的数据。在initCamera里设置聚焦模式：

			List allFocus = myParam.getSupportedFocusModes();			for(String ff:allFocus){				Log.i(tag, ff + ...FOCUS...);			}			if(allFocus.contains(Camera.Parameters.FLASH_MODE_AUTO)){				myParam.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);  				Focus_Mode = 1;			}			else if(allFocus.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)){				myParam.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);  // FOCUS_MODE_CONTINUOUS_PICTURE FOCUS_MODE_AUTO				Focus_Mode = 2;			}			myCamera.setParameters(myParam);

然后有个GetPictureThread进行每隔一段时间聚焦并且拍照：

	class GetPictureThread implements Runnable{		public void run() {			// TODO Auto-generated method stub			while(!Thread.currentThread().isInterrupted()){				if(myCamera != null && isPreview){					if(Focus_Mode == 1 && (!isFocusing)){						myCamera.autoFocus(mAutoFocusCallback);					}					else if(Focus_Mode == 2){						myCamera.takePicture(myShutterCallback, null, myJpegCallback);					}					try {						Thread.sleep(3000);					} catch (InterruptedException e) {						// TODO Auto-generated catch block						e.printStackTrace();						Thread.currentThread().interrupt();					}				}			}		}	}

原来设的GetPictureThread是每隔1200毫秒触发一次，在中兴的Geek手机上一切良好。在华为G700上，总是拍一张就挂，挂的log如下：

12-07 18:05:33.227: D/dalvikvm(13589): threadid=11: exiting12-07 18:05:33.227: W/dalvikvm(13589): threadid=11: thread exiting with uncaught exception (group=0x417669a8)12-07 18:05:33.230: E/AndroidRuntime(13589): FATAL EXCEPTION: Thread-117712-07 18:05:33.230: E/AndroidRuntime(13589): java.lang.RuntimeException: autoFocus failed12-07 18:05:33.230: E/AndroidRuntime(13589): 	at android.hardware.Camera.native_autoFocus(Native Method)12-07 18:05:33.230: E/AndroidRuntime(13589): 	at android.hardware.Camera.autoFocus(Camera.java:1120)12-07 18:05:33.230: E/AndroidRuntime(13589): 	at org.yanzi.rectphoto_wuzhou.RectPhoto$GetPictureThread.run(RectPhoto.java:428)12-07 18:05:33.230: E/AndroidRuntime(13589): 	at java.lang.Thread.run(Thread.java:838)12-07 18:05:33.240: I/Camera(13589): handleMessage: 2

反正就是auto focus出问题了，单看这里的log看不出所以然来。话说2000元买的G'700还是支持自动聚焦的吧。截取所有的log又看了次，搜索关键字：autofocus，得到以下信息：

  F:.log (12 hits)	Line 12829: 12-08 10:14:19.477 D/CameraClient(  142): autoFocus (pid 10314)	Line 12831: 12-08 10:14:19.477 D/MtkCam/CamDevice(  142): (599)(Default:0)[CamDevice::autoFocus] +	Line 12834: 12-08 10:14:19.477 D/MtkCam/CamAdapter(  142): (599)(Default)[autoFocus] +	Line 12861: 12-08 10:14:19.477 D/aaa_hal (  142): [autoFocus()]	Line 12877: 12-08 10:14:19.477 D/MtkCam/CamAdapter(  142): (599)(Default)[autoFocus] -	Line 20489: 12-08 10:14:20.677 D/CameraClient(  142): autoFocus (pid 10314)	Line 20491: 12-08 10:14:20.677 D/MtkCam/CamDevice(  142): (142)(Default:0)[CamDevice::autoFocus] +	Line 20503: 12-08 10:14:20.678 E/MtkCam/CamDevice(  142): (142)(Default:0)[CamDevice::autoFocus] preview is not enabled (autoFocus){#552:mediatek/hardware/camera/device/CamDevice/CamDevice.cpp}	Line 20503: 12-08 10:14:20.678 E/MtkCam/CamDevice(  142): (142)(Default:0)[CamDevice::autoFocus] preview is not enabled (autoFocus){#552:mediatek/hardware/camera/device/CamDevice/CamDevice.cpp}	Line 20512: 12-08 10:14:20.679 E/AndroidRuntime(10314): java.lang.RuntimeException: autoFocus failed	Line 20514: 12-08 10:14:20.679 E/AndroidRuntime(10314): 	at android.hardware.Camera.native_autoFocus(Native Method)	Line 20516: 12-08 10:14:20.679 E/AndroidRuntime(10314): 	at android.hardware.Camera.autoFocus(Camera.java:1120)

可以看到，上面提到preview is not enabled，竟然说preview没有开启。可我明明preview已经开启了，而且我在扫描线程里设置了判断if(myCamera != null && isPreview)。参考国外这位大大的帖子http://www.hitziger.net/blog/android-camera-autofocus-failed/ 上面提到auto focus失败原因是surfaceholder还没有被创建，换句话camera还没有开启预览就进行自动聚焦了。但其实我的扫描线程启动已经加了延迟，确保camera预览已经开启，姑且信了吧。把线程开启的地方加到了surfacechanged，因为我的initcamera是在surfacechanged里面，initcamera的最后就是startPreview。但依然出错。我加了个延迟在surfacechanged依旧报错。后来参考又一个人的帖子，在activity的onResume方法里进行mySurfaceHolder.addCallback(this);确保surfaceview已经创建了再添加回调。这样干确实严谨一点，但依旧报错。事实上这样做不是必须的，因为我把GetPictureThread去掉之后，一切ok。我加个button，拍照的时候自动聚焦，如果聚焦成功再触发takePicture也是ok的。

问题出在哪呢？最后才恍然大悟，问题在拍照的jpegCallback上，代码如下：

	PictureCallback myJpegCallback = new PictureCallback() 	{		public void onPictureTaken(byte[] data, Camera camera) {			// TODO Auto-generated method stub			Log.i(tag, myJpegCallback:onPictureTaken...);			long t1 = System.currentTimeMillis();			if(null != data){				mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);							myCamera.stopPreview();				isPreview = false;			}			Matrix matrix = new Matrix();			matrix.postRotate((float)90.0);			Bitmap rotaBitmap = Bitmap.createBitmap(mBitmap, 0, 0, mBitmap.getWidth(), mBitmap.getHeight(), matrix, false);			//Bitmap sizeBitmap = Bitmap.createScaledBitmap(rotaBitmap, 540, 800, true);			Bitmap rectBitmap = Bitmap.createBitmap(rotaBitmap, square.left, square.top, square.width(), square.height());			if(null != rectBitmap)			{							saveThread.setSaveBitmap(rectBitmap);			}			//ImageUtil.saveJpeg(rotaBitmap);			myCamera.startPreview();			isPreview = true;			long t2 = System.currentTimeMillis();			Log.i(tag, 本次保存耗时： + (t2 - t1) + 毫秒);		}	};

注意在拍照时，camera首先停止预览保存完照片后再次开启预览。尽管我加了isPreview这个标志，但这个标志位是不起啥作用的。推测，stoppreviw和startpreview的时候，camera在底层是异步处理的。也就是说程序执行到startpreview，isPreview为真了，但这时camera还没有完全开启预览，而扫描线程再次触发auto focus就会报上面的错误。后来我对这个myJpegCallback测了下时间，完全同样的代码，在geek手机上是900多毫秒左右，在G700上是1800毫秒左右，将近2秒了，所以扫描周期一定得大于这个时间。后来将扫描周期设为3秒，两个手机都ok了。但G700上偶发的也还是会报错，这是因为内存占用太多，手机速度变慢，myJpegCallback回调的周期超过了3秒，重启下手机就好了。在AutoFocusCallback里设置标志isFocusing也是必须的。

final AutoFocusCallback mAutoFocusCallback = new AutoFocusCallback() {		public void onAutoFocus(boolean success, Camera camera) {			// TODO Auto-generated method stub			isFocusing = true;			if(success){				Log.i(tag, 聚焦成功...);				myCamera.takePicture(myShutterCallback, null, myJpegCallback);			}			else{				Log.i(tag, 聚焦失败...);			}				isFocusing = false;		}	};

看来，要玩Camera还是得整个高端点的手机啊！！！

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