The file (xl/drawings/_rels/drawing1.xml.rels) contains the reference
to the PNG image file:
It's all XML so would be possible to construct something with existing
There is an existing C++ XLSX library (OpenXLSX) so possibly an
oct-file approach may work if this is more cumbersome natively in
If I'm following, that lets us embed an image file, but not a 'plot' in the Excel sense that can be later manipulated.