/// <summary>
/// Called by `ViewController.OnFrameCaptured` once per frame with the buffer processed by the image-processing pipeline in
/// `VideoCaptureDelegate.DidOutputSampleBuffer`
/// </summary>
/// <param name="buffer">The captured video frame.</param>
public void OnFrameCaptured(CVPixelBuffer buffer)
{
// Run the tracker
var request = new VNTrackObjectRequest(trackedRectangle, ObjectTracked);
request.TrackingLevel = VNRequestTrackingLevel.Accurate;
NSError error;
var requests = new[] { request };
overlay.InvokeOnMainThread(() => overlay.Clear());
trackingHandler.Perform(requests, buffer, out error);
if (error != null)
{
InvokeOnMainThread(() => overlay.Message = error.ToString());
}
}
/// <summary>
/// Asynchronously called by the Vision subsystem subsequent to `Perform` in `OnFrameCaptured`
/// </summary>
/// <param name="request">The request sent to the Vision subsystem.</param>
/// <param name="err">If not null, describes an error in Vision.</param>
private void RectanglesDetected(VNRequest request, NSError err)
{
if (err != null)
{
overlay.Message = err.ToString();
Console.Error.WriteLine(err);
return;
}
overlay.Clear();
observations = request.GetResults <VNRectangleObservation>();
overlay.StrokeColor = UIColor.Blue.CGColor;
//Draw all detected rectangles in blue
foreach (var o in observations)
{
var quad = new[] { o.TopLeft, o.TopRight, o.BottomRight, o.BottomLeft };
RectangleDetected(quad);
}
}