stb_image.h in the project is tech debt

[mulle-nat]

LOL, I always wanted to create a bug report with tech debt in the title. Now here's why.

The "stb_image.h" version in nanovg is nine years old, and a couple of revisions older than the current version.

nanovg.c uses it like this:

#ifndef NVG_NO_STB
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#endif
...
#ifndef NVG_NO_STB
int nvgCreateImage(NVGcontext* ctx, const char* filename, int imageFlags)
{

So, if you define NVG_NO_STB, you get no image functionality. You can't have your own version or get the symbols from a different library that also uses "stb_image.h".

It would be better, if the inclusion code would look like this:

#ifndef NVG_NO_STB
# ifndef NVG_NO_STB_IMAGE_IMPLEMENTATION
#  define STB_IMAGE_IMPLEMENTATION
# endif
# include <stb_image.h>
#endif

This way you could avoid creating possibly duplicate symbols when building nanovg (by setting NVG_NO_STB_IMAGE_IMPLEMENTATION) and you can still avoid "stb_image.h" altogether with NVG_NO_STB as before.
The # include <stb_image.h> will look for an installed "stb_image.h" before considering the local one.