/// <summary>
/// This acquires a new CameraFrame from the pool and copies the pixel data through the internal IBuffer.
/// </summary>
/// <param name="bmpFrame">The software bitmap from the camera</param>
/// <returns>The camera frame (with the pixel data copied already)</returns>
public CameraFrameInternal AcquireFrame(SoftwareBitmap bmpFrame, PixelFormat desiredPixelFormat)
{
lock (frameLock)
{
CameraFrameInternal frame = null;
// convert the data format and get the data size -
PixelFormat pixelFormat = PixelHelpers.ConvertFormat(bmpFrame.BitmapPixelFormat);
if (pixelFormat != desiredPixelFormat)
{
BitmapPixelFormat bitmapPixelFormat = PixelHelpers.ConvertFormat(desiredPixelFormat);
bmpFrame = SoftwareBitmap.Convert(bmpFrame, PixelHelpers.ConvertFormat(desiredPixelFormat));
}
int dataSize = PixelHelpers.GetDataSize(bmpFrame.PixelWidth, bmpFrame.PixelHeight, desiredPixelFormat);
if (freeCameraFrames.Count > 0)
{
// find a frame with the required size buffer
for (LinkedListNode <CameraFrameInternal> node = freeCameraFrames.First; node != null; node = node.Next)
{
// check if the pixel data array is the correct length
if (node.Value != null && node.Value?.PixelData?.Length == dataSize)
{
// remove the frame from the free list
freeCameraFrames.Remove(node);
// add the frame to the used list (need to create a new node)
frame = node.Value;
usedCameraFrames.AddFirst(frame);
}
}
}
// if there were no free frames, create a new one
if (frame == null)
{
frame = new CameraFrameInternal(this);
frame.PixelData = new byte[dataSize];
frame.PixelDataBuffer = frame.PixelData.AsBuffer();
// add the new frame to the used camera frames list
usedCameraFrames.AddFirst(frame);
}
// copy the pixel data to the frame through the internal IBuffer
bmpFrame.CopyToBuffer(frame.PixelDataBuffer);
return(frame);
}
}
private void OnMediaFrameArrived(MediaFrameReader sender, MediaFrameArrivedEventArgs args)
{
bool getFrame = false;
lock (stateLock)
{
getFrame = (State == CameraState.CapturingContinuous || State == CameraState.CapturingSingle);
// quickly handle state changes here (only changes if we're capturing a single image)
if (State == CameraState.CapturingSingle)
{
State = CameraState.Ready;
}
}
CameraFrameInternal frame = null;
if (getFrame)
{
frame = GetFrameFromMediaFrameReader(sender);
}
if (frame != null)
{
// clean up state after frame
if (CaptureMode == CaptureMode.SingleLowLatency)
{
// release previous frame and addref current frame
if (latestFrame != null)
{
latestFrame.Release();
}
// add ref for the camera
frame.AddRef();
latestFrame = frame;
}
// callback any registered listeners
OnFrameCaptured?.Invoke(this, frame);
}
}
public void ReleaseFrame(CameraFrameInternal frame)
{
lock (frameLock)
{
// remove the frame from the used list and add to the free list
if (frame != null)
{
LinkedListNode <CameraFrameInternal> frameNode = usedCameraFrames.Find(frame);
// if the frame was found, add to the free pile and remove from the used list
if (frameNode != null)
{
// need to create a new node as nodes don't swap between linked lists
freeCameraFrames.AddFirst(frameNode.Value);
// remove from the current list
usedCameraFrames.Remove(frameNode);
}
}
}
}
private CameraFrameInternal GetFrameFromMediaFrameReader(MediaFrameReader frameReader)
{
// get the latest frame
MediaFrameReference frameReference = frameReader?.TryAcquireLatestFrame();
VideoMediaFrame videoFrame = frameReference?.VideoMediaFrame;
SoftwareBitmap frameBmp = videoFrame?.SoftwareBitmap;
CameraFrameInternal frame = null;
if (frameBmp != null)
{
// get a camera frame and populate with the correct data for this frame - acquire copies the bitmap to the frame
frame = framePool.AcquireFrame(frameBmp, desiredPixelFormat);
frame.PixelFormat = desiredPixelFormat;
frame.Resolution = Resolution;
frame.FrameTime = frameReference.SystemRelativeTime.HasValue ? frameReference.SystemRelativeTime.Value.TotalSeconds : 0.0;
frame.Exposure = frameReference.Duration.TotalSeconds;
frame.Gain = Gain;
if (KeepSoftwareBitmap)
{
frame.SoftwareBitmap = frameBmp;
}
else
{
frameBmp.Dispose();
}
// extrinsics and intrinsics
frame.Extrinsics = GetExtrinsics(frameReference.CoordinateSystem);
frame.Intrinsics = ConvertIntrinsics(frameReference.VideoMediaFrame.CameraIntrinsics);
}
frameReference?.Dispose();
return(frame);
}
