png_set_swap(png); has no effect?

[dartheditous]

Hi,

I hope this is the right place to ask. I've been testing writing of 16-bit PNG files and it seems like png_set_swap(png); is doing nothing. Whether I set it or not, my output files are binary identical, and comes out looking wrong (unless I swap the bytes myself).

I'm using png_write_row and writing each row one at a time. The source is the data() pointer of a vector of uint16_t.

I compiled libpng16.lib straight out of the box using Visual Studio, if that might make a difference. Is PNG_SWAP_BYTES already set by default? Or is swapping disabled in some way that's not obvious from the source code?