/** Stops the stream. */
public void stop()
{
lock (this)
{
if (mCamera != null)
{
if (mMode == MODE_MEDIACODEC_API)
{
mCamera.SetPreviewCallbackWithBuffer(null);
}
if (mMode == MODE_MEDIACODEC_API_2)
{
((SurfaceView)mSurfaceView).removeMediaCodecSurface();
}
base.stop();
// We need to restart the preview
if (!mCameraOpenedManually)
{
destroyCamera();
}
else
{
try
{
startPreview();
}
catch (RuntimeException e)
{
e.PrintStackTrace();
}
}
}
}
}
// Stop preview and release the camera
private void stopPreviewAndReleaseCamera()
{
if (camera != null)
{
camera.SetPreviewCallbackWithBuffer(null);
stopPreview();
camera.Release();
camera = null;
}
}
private void configureCameraAndStartPreview(Android.Hardware.Camera camera)
{
// Setting camera parameters when preview is running can cause crashes on some android devices
stopPreview();
// Configure camera orientation. This is needed for both correct preview orientation
// and recognition
orientation = getCameraOrientation();
camera.SetDisplayOrientation(orientation);
// Configure camera parameters
Android.Hardware.Camera.Parameters parameters = camera.GetParameters();
// Select preview size. The preferred size for Text Capture scenario is 1080x720. In some scenarios you might
// consider using higher resolution (small text, complex background) or lower resolution (better performance, less noise)
cameraPreviewSize = null;
foreach (Android.Hardware.Camera.Size size in parameters.SupportedPreviewSizes)
{
if (size.Height <= 720 || size.Width <= 720)
{
if (cameraPreviewSize == null)
{
cameraPreviewSize = size;
}
else
{
int resultArea = cameraPreviewSize.Width * cameraPreviewSize.Height;
int newArea = size.Width * size.Height;
if (newArea > resultArea)
{
cameraPreviewSize = size;
}
}
}
}
parameters.SetPreviewSize(cameraPreviewSize.Width, cameraPreviewSize.Height);
// Zoom
parameters.Zoom = cameraZoom;
// Buffer format. The only currently supported format is NV21
parameters.PreviewFormat = Android.Graphics.ImageFormatType.Nv21;
// Default focus mode
parameters.FocusMode = Android.Hardware.Camera.Parameters.FocusModeAuto;
// Done
camera.SetParameters(parameters);
// The camera will fill the buffers with image data and notify us through the callback.
// The buffers will be sent to camera on requests from recognition service (see implementation
// of ITextCaptureService.Callback.onRequestLatestFrame above)
camera.SetPreviewCallbackWithBuffer(cameraPreviewCallback);
// Clear the previous recognition results if any
clearRecognitionResults();
// Width and height of the preview according to the current screen rotation
int width = 0;
int height = 0;
switch (orientation)
{
case 0:
case 180:
width = cameraPreviewSize.Width;
height = cameraPreviewSize.Height;
break;
case 90:
case 270:
width = cameraPreviewSize.Height;
height = cameraPreviewSize.Width;
break;
}
// Configure the view scale and area of interest (camera sees it as rotated 90 degrees, so
// there's some confusion with what is width and what is height)
surfaceViewWithOverlay.setScaleX(surfaceViewWithOverlay.Width, width);
surfaceViewWithOverlay.setScaleY(surfaceViewWithOverlay.Height, height);
// Area of interest
int marginWidth = (areaOfInterestMargin_PercentOfWidth * width) / 100;
int marginHeight = (areaOfInterestMargin_PercentOfHeight * height) / 100;
surfaceViewWithOverlay.setAreaOfInterest(
new Rect(marginWidth, marginHeight, width - marginWidth,
height - marginHeight));
// Start preview
camera.StartPreview();
setCameraFocusMode(Android.Hardware.Camera.Parameters.FocusModeAuto);
autoFocus(finishCameraInitialisationAutoFocusCallback);
inPreview = true;
}
