Following recent security updates to macOS and iPadOS, they now refuse to
display bitmaps generated by addon graphics/bmp, or any bitmaps shipped
with j904. For example: /Applications/j904/addons/graphics/bmp/toucan.bmp

However, if I copy this BMP file to my iCloud Drive, I can display it okay
on a pre-Monterey macOS. This applies to all BMPs in the latest addons
folder (I count 11 such files).

Other image formats: .jpg, .png are not affected (not fully tested).

BUT macOS and iPadOS do still display bitmaps. I've verified this by
generating one of the sample BMP files published in
https://en.wikipedia.org/wiki/BMP_file_format
I'm happy to post my code, but it's only noise at this stage. The point is:
Apple has not withdrawn support for BMP, but tightened its checks for
compliance with the spec.

This has broken viewmat in j901-for-iOS.

It would be good to fix addon: graphics/bmp to generate Apple-compliant
BMPs, and replace the bad BMPs in all addons shipped with j904. That would
allow users to fix viewmat in j901-for-iOS without having to wait for the
bug release. But I cannot find the bug in graphics/bmp.

In an earlier thread, I promised to take the matter up with Apple. I did,
but their reply is overdue.

I am aware that viewmat in jqt now uses PNG not BMP. I confirm that the
latest version of graphics/viewmat generates correct PNGs which display
okay on iPadOS, using the Files app. But j901-for-iOS needs Swift
code-changes and a full re-install from App Store before it can correctly
handle the resulting ~temp/viewmat.png which will replace ~temp/vmat.bmp .
Simple in principle but messy in practice. I haven't worked out how best to
do it.

Ian Clark
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