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L_DicomGetOverlayAttributes

Summary

Retrieves the attributes of the overlay at the specified index.

Syntax

#include "ltdic.h"

L_LTDIC_API L_UINT16 L_DicomGetOverlayAttributes(hDS, uOverlayIndex, pOverlayAttributes, uStructSize, pGroupNumber, pIsOverlayInDataset, uFlags)

Parameters

HDICOMDS hDS

A DICOM handle.

L_UINT uOverlayIndex

The index of the overlay for which to get the attributes. This index is zero-based.

pOVERLAYATTRIBUTES pOverlayAttributes

Pointer to a structure to be updated with the overlay attributes.

L_UINT uStructSize

Size of the OVERLAYATTRIBUTES structure. Pass sizeof(OVERLAYATTRIBUTES).

L_INT * pGroupNumber

Pointer to a variable to be updated with the group number for this overlay.

L_BOOL * pIsOverlayInDataset

Pointer to a variable to be updated with TRUE if the overlay data exists inside this dataset and updated with FALSE if the if the overlay data is in another dataset.

L_UINT uFlags

Reserved for future use. Pass 0.

Returns

Value	Meaning
DICOM_SUCCESS	The function was successful.
>0	An error occurred. Refer to Return Codes.

Comments

This function will retrieve the attributes of an overlay and store their values in the structure pointed to by pOverlayAttributes.

pOverlayAttributes->uStructSize will be set to the value of the parameter uStructSize.

Most of the members of the structure pOverlayAttributes are based on the "Overlay Plane Module Attributes" in the DICOM standard.

If the overlay data is embedded in the "Image Pixel Data" (7FE0,0010), the flag OVERLAY_USEBITPLANE will be set inside pOverlayAttributes->uFlags. If this flag is not set then the overlay data is stored in the "Overlay Data" (60xx,3000) element and in this case you can call L_DicomGetOverlayBitmap to get the data for that overlay.

pOverlayAttributes->ptOrigin will hold the value of the "Overlay Origin" (60xx,0050) element , however the upper left pixel of the image will have the coordinate 0\0 , instead of 1\1( as in the DICOM standard).

This function will always set pOverlayAttributes->crColor to black.

For multi-frame overlays, this function will update pOverlayAttributes->nNumFramesInOverlay with the value of "Number of Frames in Overlay" (60xx,0015) element and pOverlayAttributes-> uImageFrameOrigin with the value of "Image Frame Origin" (60xx,0051) element.

pOverlayAttributes->szActivationLayer will be updated with the value of the element "Overlay Activation Layer" (60xx,1001).

Because DICOM uses "Repeating Groups" to represent multiple overlays, pGroupNumber is useful in knowing under which group number this overlay exists.