jp2_locator::get_file_pos

Returns the absolute location of the box to which this locator refers, within the original file to which it belongs. If the file is being delivered by a remote server to a dynamically evolving cache, accessed via a kdu_cache object, a linear file structure may not exist locally. Nevertheless, even in this case, the available data is generally referenced to an original file so that absolute locations can usually be established. The only exception to this is where a JP2 box has been synthesized by the server (stream equivalent) or is being served as an incremental code-stream (one whose open jp2_input_box can be passed to kdu_codestream::create). In these circumstances, the box does not have a file location and this function will return -1.

The file position corresponds to the first byte of the relevant box header, not the box contents, which appear after its header.