Replace old stb_image 1.18 with stb_image 2.30 and stb_image_write 1.16

[illwieckz]

Replace old stb_image with stb_image 2.30 and stb_image_write 1.16.

Pulled from https://github.com/nothings/stb
Commit 013ac3beddff3dbffafd5177e7972067cd2b5083

Fixes #13:

• crunch is known to not properly grok all png format variants #13

[illwieckz]

To know the modifications that was previously added to the old copy of stb_image, one can compare from the commit before this branch the example1/stb_image.h file with the crnlib/crn_image_utils.cpp file which was just a copy of the same stb_image.h at the time plus some minor changes.

The big difference is that previously, the stb functions were declared in namespace crnlib, it si not anymore.

Other changes is that many minor fixes implemented on crnlib/crn_image_utils.cpp are now lost, but all of them are probably useless and has been likely implemented by upstream in newer stb_image.h. In fact, I managed to produce both Linux, MinGW, macOS and FreeBSD builds without problems.

I guess it means this can introduce a mismatch if crnlib is linked with another software having built another version of stb.

[illwieckz]

The update of stb_image will also help to make the examples less Windows-centric, as the very old stb_image was Windows-centric and the copy in crnlib received fixes before.

[illwieckz]

So, Appveyor says it also builds on MSVC. So it builds everywhere as I verified myself the others.

[DolceTriade]

Did you make any modifications to the upstream file?

[illwieckz]

Except the changes done in stb_image_write: prevent int to overflow before converting it to size_t commit (which are preventing some integers to overflow as reported by CodeQL), the stb files are an unmodified a copy-paste from stb upstream. I plan to submit the patch to stb upstream. My purpose is that future stb updates would just copy-paste the stb upstream.

Edit: I submitted the changes upstream:

• stb_image: prevent int to overflow before converting it to size_t nothings/stb#1658

[illwieckz]

This reintroduces a sprintf.

They have a pending PR for it:

• FIX: use snprintf instead of sprintf nothings/stb#1619

Edit: I implemented a similar fix.

[slipher]

Headers of a dependent library don't really belong in the source list. Same goes for example3

[illwieckz]

Isn't it what CMake use to know the source has to be rebuilt if the header changes?

[slipher]

No. AFAIK the only use is to index it in IDE projects.

[illwieckz]

Ah, wouldn't it be a good idea though? I see there are some VS projects there but they are likely unmaintained and will be out of date once this is merged.

[slipher]

No. In the VS project setting, headers that are part of the Crunch library should be in the library's sources, not the example sources.

[illwieckz]

OK I removed them.