public static List <OverlayPlaneGraphic> CreateOverlayPlaneGraphics(Frame frame, OverlayPlaneModuleIod overlaysFromPresentationState)
{
ISopDataSource dataSource = frame.ParentImageSop.DataSource;
OverlayPlaneModuleIod overlaysIod = new OverlayPlaneModuleIod(dataSource);
List <OverlayPlaneGraphic> overlayPlaneGraphics = new List <OverlayPlaneGraphic>();
bool failedOverlays = false;
foreach (var overlayPlane in overlaysIod)
{
// DICOM 2009 PS 3.3 Section C.9.3.1.1 specifies the rule: NumberOfFramesInOverlay+ImageFrameOrigin-1 must be <= NumberOfFrames
if (!overlayPlane.IsValidMultiFrameOverlay(frame.ParentImageSop.NumberOfFrames))
{
failedOverlays = true;
Platform.Log(LogLevel.Warn, new DicomOverlayDeserializationException(overlayPlane.Group, OverlayPlaneSource.Image), "Encoding error encountered while reading overlay from image headers.");
continue;
}
try
{
byte[] overlayData = dataSource.GetFrameData(frame.FrameNumber).GetNormalizedOverlayData(overlayPlane.Index + 1);
overlayPlaneGraphics.Add(new OverlayPlaneGraphic(overlayPlane, overlayData, OverlayPlaneSource.Image));
// if overlay data is null, the data source failed to retrieve the overlay data for some reason, so we also treat it as an encoding error
// this is different from if the overlay data is zero-length, which indicates that the retrieval succeeded, but that the overlay data for the frame is empty
if (overlayData == null)
{
throw new NullReferenceException();
}
}
catch (Exception ex)
{
failedOverlays = true;
Platform.Log(LogLevel.Warn, new DicomOverlayDeserializationException(overlayPlane.Group, OverlayPlaneSource.Image, ex), "Failed to load overlay from the image header.");
}
}
if (overlaysFromPresentationState != null)
{
foreach (var overlayPlane in overlaysFromPresentationState)
{
// if overlay data is missing, treat as an encoding error
if (!overlayPlane.HasOverlayData)
{
failedOverlays = true;
Platform.Log(LogLevel.Warn, new DicomOverlayDeserializationException(overlayPlane.Group, OverlayPlaneSource.PresentationState), "Encoding error encountered while reading overlay from softcopy presentation state.");
continue;
}
try
{
byte[] overlayData;
// try to compute the offset in the OverlayData bit stream where we can find the overlay frame that applies to this image frame
int overlayFrame, bitOffset;
if (overlayPlane.TryGetRelevantOverlayFrame(frame.FrameNumber, frame.ParentImageSop.NumberOfFrames, out overlayFrame) &&
overlayPlane.TryComputeOverlayDataBitOffset(overlayFrame, out bitOffset))
{
// offset found - unpack only that overlay frame
var od = new OverlayData(bitOffset,
overlayPlane.OverlayRows,
overlayPlane.OverlayColumns,
overlayPlane.IsBigEndianOW,
overlayPlane.OverlayData);
overlayData = od.Unpack();
}
else
{
// no relevant overlay frame found - i.e. the overlay for this image frame is blank
overlayData = new byte[0];
}
overlayPlaneGraphics.Add(new OverlayPlaneGraphic(overlayPlane, overlayData, OverlayPlaneSource.PresentationState));
}
catch (Exception ex)
{
failedOverlays = true;
Platform.Log(LogLevel.Warn, new DicomOverlayDeserializationException(overlayPlane.Group, OverlayPlaneSource.PresentationState, ex), "Failed to load overlay from softcopy presentation state.");
}
}
}
if (failedOverlays)
{
// add an error graphic if any overlays are not being displayed due to deserialization errors.
overlayPlaneGraphics.Add(new ErrorOverlayPlaneGraphic(SR.MessageErrorDisplayingOverlays));
}
return(overlayPlaneGraphics);
}
protected override ISopFrameData GetFrameData(int frameNumber)
{
return(_sopDataSource.GetFrameData(frameNumber));
}