/// <summary>
/// https://codelabs.developers.google.com/codelabs/camerax-getting-started#3
/// </summary>
private void StartCamera()
{
var cameraProviderFuture = ProcessCameraProvider.GetInstance(this);
cameraProviderFuture.AddListener(new Runnable(() =>
{
// Used to bind the lifecycle of cameras to the lifecycle owner
var cameraProvider = (ProcessCameraProvider)cameraProviderFuture.Get();
// Preview
var preview = new Preview.Builder().Build();
preview.SetSurfaceProvider(viewFinder.CreateSurfaceProvider());
// Take Photo
this.imageCapture = new ImageCapture.Builder().Build();
// Frame by frame analyze
var imageAnalyzer = new ImageAnalysis.Builder().Build();
imageAnalyzer.SetAnalyzer(cameraExecutor, new LuminosityAnalyzer(luma =>
Log.Debug(TAG, $"Average luminosity: {luma}")
));
// Select back camera as a default, or front camera otherwise
CameraSelector cameraSelector = null;
if (cameraProvider.HasCamera(CameraSelector.DefaultBackCamera) == true)
{
cameraSelector = CameraSelector.DefaultBackCamera;
}
else if (cameraProvider.HasCamera(CameraSelector.DefaultFrontCamera) == true)
{
cameraSelector = CameraSelector.DefaultFrontCamera;
}
else
{
throw new System.Exception("Camera not found");
}
try
{
// Unbind use cases before rebinding
cameraProvider.UnbindAll();
// Bind use cases to camera
cameraProvider.BindToLifecycle(this, cameraSelector, preview, imageCapture, imageAnalyzer);
}
catch (Exception exc)
{
Log.Debug(TAG, "Use case binding failed", exc);
Toast.MakeText(this, $"Use case binding failed: {exc.Message}", ToastLength.Short).Show();
}
}), ContextCompat.GetMainExecutor(this)); //GetMainExecutor: returns an Executor that runs on the main thread.
}
// Declare and bind preview, capture and analysis use cases
private void BindCameraUseCases()
{
// Get screen metrics used to setup camera for full screen resolution
var metrics = new DisplayMetrics();
viewFinder.Display.GetRealMetrics(metrics);
Log.Debug(Tag, "Screen metrics: " + metrics);
var screenAspectRatio = AspectRatio(metrics.WidthPixels, metrics.HeightPixels);
Log.Debug(Tag, "Preview aspect ratio: " + screenAspectRatio);
var rotation = viewFinder.Display.Rotation;
// CameraProvider
if (cameraProvider == null)
{
throw new Java.Lang.IllegalStateException("Camera initialization failed.");
}
// CameraSelector
var cameraSelector = (new CameraSelector.Builder()).RequireLensFacing(lensFacing).Build();
// Preview
preview = new Preview.Builder()
// We request aspect ratio but no resolution
.SetTargetAspectRatio(screenAspectRatio)
// Set initial target rotation
.SetTargetRotation((int)rotation)
.Build();
// ImageCapture
imageCapture = new ImageCapture.Builder()
.SetCaptureMode(ImageCapture.CaptureModeMinimizeLatency)
// We request aspect ratio but no resolution to match preview config, but letting
// CameraX optimize for whatever specific resolution best fits our use cases
.SetTargetAspectRatio(screenAspectRatio)
// Set initial target rotation, we will have to call this again if rotation changes
// during the lifecycle of this use case
.SetTargetRotation((int)rotation)
.Build();
// ImageAnalysis
imageAnalyzer = new ImageAnalysis.Builder()
// We request aspect ratio but no resolution
.SetTargetAspectRatio(screenAspectRatio)
// Set initial target rotation, we will have to call this again if rotation changes
// during the lifecycle of this use case
.SetTargetRotation((int)rotation)
.Build();
// The analyzer can then be assigned to the instance
imageAnalyzer.SetAnalyzer(cameraExecutor, new LuminosityAnalyzer(
(double luma) => {
// Values returned from our analyzer are passed to the attached listener
// We log image analysis results here - you should do something useful
// instead!
Log.Debug(Tag, "Average luminosity: " + luma);
})
);
// Must unbind the use-cases before rebinding them
cameraProvider.UnbindAll();
try
{
// A variable number of use-cases can be passed here -
// camera provides access to CameraControl & CameraInfo
camera = cameraProvider.BindToLifecycle(
(ILifecycleOwner)this, cameraSelector, preview, imageCapture, imageAnalyzer);
// Attach the viewfinder's surface provider to preview use case
preview?.SetSurfaceProvider(viewFinder.CreateSurfaceProvider());
}
catch (Java.Lang.Exception exc)
{
Log.Error(Tag, "Use case binding failed: " + exc);
}
}