stb_image: read image into a buffer allocated outside of stbi

[attilaz]

It could be implemented to output into a preallocated buffer like in stb_image_resize or with the ability to set a custom allocator for output buffer alloc/free. I am not interested in using custom allocator for internal, temporary buffers but others might find that useful too.

[attilaz]

The current STBI_MALLOC in stb_image v2.0 is good enough for me. Thanks for adding it. So If you don't plan to modify the interface to add a preallocated buffer for output this issue can be closed.

[nothings]

I still want to add that.

[attilaz]

Great. Thanks.

[ratchetfreak]

I mentioned this in #435 but I'll repeat it here for prosperity

Providing a row stride with the buffer would then be very nice addition for the APIs that require aligned rows.

[fishcu]

I'm also interested in this, for reasons already mentioned in #435 (namely non-trivial row stride). Is this still on the todo list, or maybe available in a fork already somewhere?

[mokafolio]

I'd be interested in this addition, too.

[kayomn]

I'm also interested in this. My game engine uses custom allocators everywhere and while I've done some hacks to STB image in order to accommodate, I think it would be nicer if it was exposed as part of the header by default.

[ronaaron]

Adding my voice to the "I'm interested in this" as well. Really interested!

[Karutoh]

This feature would be nice in Vulkan so that you may decode directly to the ppData parameter in vkMapMemory for a VkBuffer. This would reduce the amount of processing required. Otherwise the end-user will be forced to copy all data themselves to the mapped memory.