/**
* Opens the camera and starts sending preview frames to the underlying detector. The preview
* frames are not displayed.
*
* @throws IOException if the camera's preview texture or display could not be initialized
*/
@RequiresPermission(Manifest.permission.CAMERA)
public CameraSource start() throws IOException {
synchronized (mCameraLock) {
if (mCamera != null) {
return this;
}
mCamera = createCamera();
// SurfaceTexture was introduced in Honeycomb (11), so if we are running and
// old version of Android. fall back to use SurfaceView.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
mDummySurfaceTexture = new SurfaceTexture(DUMMY_TEXTURE_NAME);
mCamera.setPreviewTexture(mDummySurfaceTexture);
} else {
mDummySurfaceView = new SurfaceView(mContext);
mCamera.setPreviewDisplay(mDummySurfaceView.getHolder());
}
mCamera.startPreview();
mProcessingThread = new Thread(mFrameProcessor);
mFrameProcessor.setActive(true);
mProcessingThread.start();
}
return this;
}
/**
* Opens the camera and starts sending preview frames to the underlying detector. The supplied
* surface holder is used for the preview so frames can be displayed to the user.
*
* @param surfaceHolder the surface holder to use for the preview frames
* @throws IOException if the supplied surface holder could not be used as the preview display
*/
@RequiresPermission(Manifest.permission.CAMERA)
public CameraSource start(SurfaceHolder surfaceHolder) throws IOException {
synchronized (mCameraLock) {
if (mCamera != null) {
return this;
}
mCamera = createCamera();
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
mProcessingThread = new Thread(mFrameProcessor);
mFrameProcessor.setActive(true);
mProcessingThread.start();
}
return this;
}
/**
* Closes the camera and stops sending frames to the underlying frame detector.
*
* <p>This camera source may be restarted again by calling {@link #start()} or {@link
* #start(SurfaceHolder)}.
*
* <p>Call {@link #release()} instead to completely shut down this camera source and release the
* resources of the underlying detector.
*/
public void stop() {
synchronized (mCameraLock) {
mFrameProcessor.setActive(false);
if (mProcessingThread != null) {
try {
// Wait for the thread to complete to ensure that we can't have multiple threads
// executing at the same time (i.e., which would happen if we called start too
// quickly after stop).
mProcessingThread.join();
} catch (InterruptedException e) {
Log.d(TAG, mContext.getString(R.string.processing_interrupted));
}
mProcessingThread = null;
}
// clear the buffer to prevent oom exceptions
mBytesToByteBuffer.clear();
if (mCamera != null) {
mCamera.stopPreview();
mCamera.setPreviewCallbackWithBuffer(null);
try {
// We want to be compatible back to Gingerbread, but SurfaceTexture
// wasn't introduced until Honeycomb. Since the interface cannot use a SurfaceTexture, if
// the
// developer wants to display a preview we must use a SurfaceHolder. If the developer
// doesn't
// want to display a preview we use a SurfaceTexture if we are running at least Honeycomb.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
mCamera.setPreviewTexture(null);
} else {
mCamera.setPreviewDisplay(null);
}
} catch (Exception e) {
Log.e(TAG, mContext.getString(R.string.failed_to_clear_preview) + e);
}
mCamera.release();
mCamera = null;
}
}
}
/** Stops the camera and releases the resources of the camera and underlying detector. */
public void release() {
synchronized (mCameraLock) {
stop();
mFrameProcessor.release();
}
}
