Grouped images are not preserved when reading and writing xlsx files

[rpg600]

Issue: Grouped images are not preserved when reading and writing xlsx files

Environment

PhpSpreadsheet version: 5.2.0 (also affects earlier versions)
PHP version: 8.x
File format: .xlsx (Office Open XML)

Description

When loading an Excel file containing grouped images and saving it back, the images inside the group are lost.

Screenshot

test file

group_issue.xlsx

Xml file comparison

original_drawing.xml

generated_drawing.xml

Xml debug

works : 
<xdr:twoCellAnchor>
  <xdr:pic>
    <a:blip r:embed="rId1"/>
  </xdr:pic>
</xdr:twoCellAnchor>

don't work :
<xdr:twoCellAnchor>
  <xdr:grpSp>              ← THE PROBLEM
    <xdr:pic>
      <a:blip r:embed="rId2"/>
    </xdr:pic>
    <xdr:pic>
      <a:blip r:embed="rId3"/>
    </xdr:pic>
  </xdr:grpSp>
</xdr:twoCellAnchor>

What happens

1) Reader/Xlsx.php (~line 1489)
Parses <xdr:pic> elements directly under <xdr:twoCellAnchor>
Does NOT parse <xdr:pic> inside <xdr:grpSp>
Grouped images are never loaded into DrawingCollection

2) Writer/Xlsx/Drawing.php
Regenerates Drawing XML from DrawingCollection only
Grouped images are not in the collection
Result: Grouped images omitted from output

Workaround:

Manually ungroup all images before processing (not always possible)

Solutions :

Option 1: Full Group Support (complex)
Option 2: Append the unsupported xml elements (pass-through)

[oleibman]

Agreed - we do not yet handle grouped images. It looks like it could be very difficult to add them. Would it be useful to you if the reader processed the grouped images as individual images, so that you would lose the groupings but not the images? This would still be difficult to implement, but not as difficult as full support.

[rpg600]

@oleibman Yes, as long as the image position stays the same.