C Specification

The xrGetMarkerStringML function is defined as:

// Provided by XR_ML_marker_understanding
XrResult xrGetMarkerStringML(
    XrMarkerDetectorML                          markerDetector,
    XrMarkerML                                  marker,
    uint32_t                                    bufferCapacityInput,
    uint32_t*                                   bufferCountOutput,
    char*                                       buffer);

Parameters

Parameter Descriptions

  • markerDetector is the detector object to retrieve marker information from.

  • marker is the marker atom to be examined.

  • bufferCapacityInput is the capacity of the buffer, or 0 to indicate a request to retrieve the required capacity.

  • bufferCountOutput is a pointer to the count of characters written to buffer (including the terminating '\0'), or a pointer to the required capacity in the case that bufferCapacityInput is insufficient.

  • buffer is a pointer to an application-allocated buffer that should be filled with the QR code’s contents. It can be NULL if bufferCapacityInput is 0.

  • See the Buffer Size Parameters section for a detailed description of retrieving the required buffer size.

Description

Get the string value of a marker, such as the QR encoded string. xrCreateMarkerSpaceML must only be called when the state of the detector is XR_MARKER_DETECTOR_STATUS_READY_ML.

If the marker does not have an associated string value, the runtime must return XR_ERROR_MARKER_DETECTOR_INVALID_DATA_QUERY_ML.

If xrGetMarkerDetectorStateML has not been called and returned XR_MARKER_DETECTOR_STATUS_READY_ML since the last invocation of xrSnapshotMarkerDetectorML, the runtime must return XR_ERROR_CALL_ORDER_INVALID.

This function follows the two-call idiom for filling the buffer.

The runtime must return XR_ERROR_MARKER_INVALID_ML if the marker atom is invalid.

Valid Usage (Implicit)
Return Codes
On success, this command returns

  • XR_SUCCESS

  • XR_SESSION_LOSS_PENDING

On failure, this command returns

  • XR_ERROR_FUNCTION_UNSUPPORTED

  • XR_ERROR_VALIDATION_FAILURE

  • XR_ERROR_RUNTIME_FAILURE

  • XR_ERROR_HANDLE_INVALID

  • XR_ERROR_INSTANCE_LOST

  • XR_ERROR_SESSION_LOST

  • XR_ERROR_MARKER_INVALID_ML

  • XR_ERROR_MARKER_DETECTOR_INVALID_DATA_QUERY_ML

See Also

XR_ML_marker_understanding, XrMarkerDetectorML, XrMarkerML, xrGetMarkersML

Document Notes

For more information, see the OpenXR Specification

This page is extracted from the OpenXR Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2024, The Khronos Group Inc.

This work is licensed under a Creative Commons Attribution 4.0 International License.