Example for spng_set_png_stream()

[JanGerber]

Is there an example how to use the spng_set_png_stream() function?

[randy408]

One example is the spng_set_png_file() function which is essentially spng_set_png_stream(ctx, file_read_fn, file) where file_read_fn looks like this:

libspng/spng/spng.c

Lines 5024 to 5036 in e5c1fc4

	static int file_read_fn(spng_ctx *ctx, void *user, void *data, size_t n)
	{
	FILE *file = user;
	(void)ctx;
	if(fread(data, n, 1, file) != 1)
	{
	if(feof(file)) return SPNG_IO_EOF;
	else return SPNG_IO_ERROR;
	}
	return 0;
	}

For writing file_write_fn is used, it's right after file_read_fn in the same file.

There is documentation on the read and write callbacks: https://libspng.org/docs/context/#spng_read_fn, https://libspng.org/docs/context/#spng_write_fn