stb_image: Account for tRNS chunk in non-paletted images.

So we report channels_in_file correctly. Fixes #329.
2017-07-23 01:41:12 -07:00 · 2017-07-23 01:41:12 -07:00 · 0fbbda56fa
parent 7725f8b9cd
commit 0fbbda56fa
1 changed files with 3 additions and 0 deletions
--- a/stb_image.h
+++ b/stb_image.h
@ -4822,6 +4822,9 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp)
               if (req_comp >= 3) s->img_out_n = req_comp;
               if (!stbi__expand_png_palette(z, palette, pal_len, s->img_out_n))
                  return 0;
+            } else if (has_trans) {
+               // non-paletted image with tRNS -> source image has (constant) alpha
+               ++s->img_n;
            }
            STBI_FREE(z->expanded); z->expanded = NULL;
            return 1;