public void DidOutputMetadataObjects(AVCaptureMetadataOutput captureOutput,
AVMetadataObject[] metadataObjects, AVCaptureConnection connection)
{
var lostFaces = _faceLayers.Keys.ToList();
foreach (var metadata in metadataObjects.OfType <AVMetadataFaceObject>())
{
var transformed = VideoPreviewLayer.GetTransformedMetadataObject(metadata);
var face = transformed as AVMetadataFaceObject;
var bounds = transformed.Bounds;
if (lostFaces.Contains(face.FaceID))
{
lostFaces.Remove(face.FaceID);
}
CALayer faceLayer;
if (!_faceLayers.TryGetValue(face.FaceID, out faceLayer))
{
faceLayer = CreateFaceLayer();
_overlayLayer.AddSublayer(faceLayer);
_faceLayers.Add(face.FaceID, faceLayer);
}
faceLayer.Transform = CATransform3D.Identity;
faceLayer.Frame = bounds;
if (face.HasRollAngle)
{
var transform = RollTransform(face.RollAngle);
faceLayer.Transform = faceLayer.Transform.Concat(transform);
}
if (face.HasYawAngle)
{
var transform = YawTransform(face.YawAngle);
faceLayer.Transform = faceLayer.Transform.Concat(transform);
}
}
RemoveLostFaces(lostFaces);
}
// Updates the region of interest with a proposed region of interest ensuring
// the new region of interest is within the bounds of the video preview. When
// a new region of interest is set, the region of interest is redrawn.
public void SetRegionOfInterestWithProposedRegionOfInterest(CGRect proposedRegionOfInterest)
{
// We standardize to ensure we have positive widths and heights with an origin at the top left.
var videoPreviewRect = VideoPreviewLayer.MapToLayerCoordinates(new CGRect(0, 0, 1, 1)).Standardize();
// Intersect the video preview view with the view's frame to only get
// the visible portions of the video preview view.
var visibleVideoPreviewRect = CGRect.Intersect(videoPreviewRect, Frame);
var oldRegion = RegionOfInterest;
var newRegion = proposedRegionOfInterest.Standardize();
// Move the region of interest in bounds.
if (currentControlCorner == ControlCorner.None)
{
nfloat xOffset = 0;
nfloat yOffset = 0;
if (!visibleVideoPreviewRect.Contains(newRegion.CornerTopLeft()))
{
xOffset = NMath.Max(visibleVideoPreviewRect.GetMinX() - newRegion.GetMinX(), 0);
yOffset = NMath.Max(visibleVideoPreviewRect.GetMinY() - newRegion.GetMinY(), 0);
}
if (!visibleVideoPreviewRect.Contains(visibleVideoPreviewRect.CornerBottomRight()))
{
xOffset = NMath.Min(visibleVideoPreviewRect.GetMaxX() - newRegion.GetMaxX(), xOffset);
yOffset = NMath.Min(visibleVideoPreviewRect.GetMaxY() - newRegion.GetMaxY(), yOffset);
}
newRegion.Offset(xOffset, yOffset);
}
// Clamp the size when the region of interest is being resized.
visibleVideoPreviewRect.Intersect(newRegion);
newRegion = visibleVideoPreviewRect;
// Fix a minimum width of the region of interest.
if (proposedRegionOfInterest.Size.Width < MinimumRegionOfInterestSize)
{
switch (currentControlCorner)
{
case ControlCorner.TopLeft:
case ControlCorner.BottomLeft:
var x = oldRegion.Location.X + oldRegion.Size.Width - MinimumRegionOfInterestSize;
newRegion = newRegion.WithX(x).WithWidth(MinimumRegionOfInterestSize);
break;
case ControlCorner.TopRight:
newRegion = newRegion.WithX(oldRegion.Location.X)
.WithWidth(MinimumRegionOfInterestSize);
break;
default:
newRegion = newRegion.WithLocation(oldRegion.Location)
.WithWidth(MinimumRegionOfInterestSize);
break;
}
}
// Fix a minimum height of the region of interest.
if (proposedRegionOfInterest.Height < MinimumRegionOfInterestSize)
{
switch (currentControlCorner)
{
case ControlCorner.TopLeft:
case ControlCorner.TopRight:
newRegion = newRegion.WithY(oldRegion.Y + oldRegion.Height - MinimumRegionOfInterestSize)
.WithHeight(MinimumRegionOfInterestSize);
break;
case ControlCorner.BottomLeft:
newRegion = newRegion.WithY(oldRegion.Y)
.WithHeight(MinimumRegionOfInterestSize);
break;
default:
newRegion = newRegion.WithLocation(oldRegion.Location)
.WithHeight(MinimumRegionOfInterestSize);
break;
}
}
RegionOfInterest = newRegion;
SetNeedsLayout();
}
void ResizeRegionOfInterestWithGestureRecognizer(UIPanGestureRecognizer pan)
{
var touchLocation = pan.LocationInView(pan.View);
var oldRegionOfInterest = RegionOfInterest;
switch (pan.State)
{
case UIGestureRecognizerState.Began:
// When the gesture begins, save the corner that is closes to
// the resize region of interest gesture recognizer's touch location.
currentControlCorner = CornerOfRect(oldRegionOfInterest, touchLocation);
break;
case UIGestureRecognizerState.Changed:
var newRegionOfInterest = oldRegionOfInterest;
switch (currentControlCorner)
{
case ControlCorner.None:
// Update the new region of interest with the gesture recognizer's translation.
var translation = pan.TranslationInView(pan.View);
// Move the region of interest with the gesture recognizer's translation.
if (RegionOfInterest.Contains(touchLocation))
{
newRegionOfInterest.X += translation.X;
newRegionOfInterest.Y += translation.Y;
}
// If the touch location goes outside the preview layer,
// we will only translate the region of interest in the
// plane that is not out of bounds.
var normalizedRect = new CGRect(0, 0, 1, 1);
if (!normalizedRect.Contains(VideoPreviewLayer.PointForCaptureDevicePointOfInterest(touchLocation)))
{
if (touchLocation.X < RegionOfInterest.GetMinX() || touchLocation.X > RegionOfInterest.GetMaxX())
{
newRegionOfInterest.Y += translation.Y;
}
else if (touchLocation.Y < RegionOfInterest.GetMinY() || touchLocation.Y > RegionOfInterest.GetMaxY())
{
newRegionOfInterest.X += translation.X;
}
}
// Set the translation to be zero so that the new gesture
// recognizer's translation is in respect to the region of
// interest's new position.
pan.SetTranslation(CGPoint.Empty, pan.View);
break;
case ControlCorner.TopLeft:
newRegionOfInterest = new CGRect(touchLocation.X, touchLocation.Y,
oldRegionOfInterest.Width + oldRegionOfInterest.X - touchLocation.X,
oldRegionOfInterest.Height + oldRegionOfInterest.Y - touchLocation.Y);
break;
case ControlCorner.TopRight:
newRegionOfInterest = new CGRect(newRegionOfInterest.X,
touchLocation.Y,
touchLocation.X - newRegionOfInterest.X,
oldRegionOfInterest.Height + newRegionOfInterest.Y - touchLocation.Y);
break;
case ControlCorner.BottomLeft:
newRegionOfInterest = new CGRect(touchLocation.X, oldRegionOfInterest.Y,
oldRegionOfInterest.Width + oldRegionOfInterest.X - touchLocation.X,
touchLocation.Y - oldRegionOfInterest.Y);
break;
case ControlCorner.BottomRight:
newRegionOfInterest = new CGRect(oldRegionOfInterest.X, oldRegionOfInterest.Y,
touchLocation.X - oldRegionOfInterest.X,
touchLocation.Y - oldRegionOfInterest.Y);
break;
}
// Update the region of intresest with a valid CGRect.
SetRegionOfInterestWithProposedRegionOfInterest(newRegionOfInterest);
break;
case UIGestureRecognizerState.Ended:
RegionOfInterestDidChange?.Invoke(this, EventArgs.Empty);
// Reset the current corner reference to none now that the resize.
// gesture recognizer has ended.
currentControlCorner = ControlCorner.None;
break;
default:
return;
}
}
