我已经完成了动作检测应用程序。当我尝试通过onPressBack方法返回到上一个活动并尝试释放摄像机时，在摄像机处于打开状态的活动中，在调用camera.release之后出现使用摄像机的错误。
这是活动中运行另一类运动检测的代码
surfaceView=(SurfaceView)findViewById(R.id.surfaceView);
mSurfaceHolder = surfaceView.getHolder();
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
// new Hour_service(surfaceView);
// Intent intent=new Intent(MainActivity.this,Hour_service.class);
// startService(intent);
txtStatus = (TextView) findViewById(R.id.txtStatus);
root =findViewById(R.id.activity_main).getRootView();
motionDetector = new MotionDetector(this, (SurfaceView) surfaceView);
motionDetector.setMotionDetectorCallback(new MotionDetectorCallback() {
@Override
public void onMotionDetected() {
Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
v.vibrate(50);
txtStatus.setText("Motion detected");
bOutput=MotionDetector.bOutput;
if (first==0) {
first++;
startTime = SystemClock.uptimeMillis();
customHandler.postDelayed(updateTimerThread, 0);
}
/* if(detection_count==5){
Intent intent = new Intent(MainActivity.this, RecorderService.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startService(intent);
}
detection_count ++ ;*/
}
@Override
public void onTooDark() {
txtStatus.setText("Too dark here");
root.setBackgroundColor(Color.parseColor("#000000"));
}
});
}
private Runnable updateTimerThread = new Runnable() {
public void run() {
updatedTime = SystemClock.uptimeMillis() - startTime;
int secs = (int) (updatedTime / 1000);
sec=secs;
if (secs>=16&&save_count>=3){
save_count=0;
first=0;
// Save Video_a;
// Stop timer
customHandler.removeCallbacks(updateTimerThread);
}else if (secs<16&&save_count<=2){
SaveImage(bOutput);
save_count++;
}
customHandler.postDelayed(this, 5000);
}
};
@Override
protected void onResume() {
super.onResume();
motionDetector.onResume();
if (motionDetector.checkCameraHardware()) {
// txtStatus.setText("Camera found");
} else {
// txtStatus.setText("No camera available");
}
}
@Override
protected void onPause() {
super.onPause();
motionDetector.onPause();
}
@Override
public void onBackPressed() {
motionDetector.setMotionDetectorCallback(null);
motionDetector.onBackPressed();
}
这是运动检测器类中的代码
class MotionDetectorThread extends Thread {
private AtomicBoolean isRunning = new AtomicBoolean(true);
public void stopDetection() {
isRunning.set(false);
}
@Override
public void run() {
while (isRunning.get()) {
long now = System.currentTimeMillis();
if (now - lastCheck > checkInterval) {
lastCheck = now;
if (nextData.get() != null) {
int[] img = ImageProcessing.decodeYUV420SPtoLuma(nextData.get(), nextWidth.get(), nextHeight.get());
// check if it is too dark
int lumaSum = 0;
for (int i : img) {
lumaSum += i;
}
if (lumaSum < minLuma) {
if (motionDetectorCallback != null) {
mHandler.post(new Runnable() {
@Override
public void run() {
motionDetectorCallback.onTooDark();
}
});
}
} else if (detector.detect(img, nextWidth.get(), nextHeight.get())) {
// check
if (motionDetectorCallback != null ) {
mHandler.post(new Runnable() {
@Override
public void run() {
Camera.Parameters params = imgCam.getParameters();
int w = params.getPreviewSize().width;
int h = params.getPreviewSize().height;
int format = params.getPreviewFormat();
YuvImage image = new YuvImage(imgByte, format, w, h, null);
ByteArrayOutputStream out = new ByteArrayOutputStream();
Rect area = new Rect(0, 0, w, h);
image.compressToJpeg(area, 100, out);
Bitmap bm = BitmapFactory.decodeByteArray(out.toByteArray(), 0, out.size());
float degrees = 90;//rotation degree
Matrix matrix = new Matrix();
matrix.setRotate(degrees);
bOutput = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), matrix, true);
// mMediaRecorder.start();
// try {
// Thread.sleep(10 * 1000); // This will recode for 10 seconds, if you don't want then just remove it.
// } catch (Exception e) {
// e.printStackTrace();
// }
// getOutputMediaFile(1);
motionDetectorCallback.onMotionDetected();
}
});
}
}
}
}
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
和我创建的一些方法
public void onResume() {
if (checkCameraHardware()) {
mCamera = getCameraInstance();
worker = new MotionDetectorThread();
worker.start();
// configure preview
previewHolder = mSurface.getHolder();
previewHolder.addCallback(surfaceCallback);
previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
}
public boolean checkCameraHardware() {
if (mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}
private Camera getCameraInstance() {
Camera c = null;
try {
if (Camera.getNumberOfCameras() >= 2) {
//if you want to open front facing camera use this line
c = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK);
} else {
c = Camera.open();
}
} catch (Exception e) {
// Camera is not available (in use or does not exist)
//txtStatus.setText("Kamera nicht zur Benutzung freigegeben");
}
return c; // returns null if camera is unavailable
}
private Camera.PreviewCallback previewCallback = new Camera.PreviewCallback() {
/**
* {@inheritDoc}
*/
@Override
public void onPreviewFrame(byte[] data, Camera cam) {
if (data == null) return;
Camera.Size size = cam.getParameters().getPreviewSize();
if (size == null) return;
consume(data, size.width, size.height);
imgByte = data;
imgCam = cam;
}
};