commit 4cfdb3c09571c22206ca38f652283be7180f8636
author Glenn Randers-Pehrson <glennrp at users.sourceforge.net> Thu Nov 26 11:49:37 2009 -0600
committer Glenn Randers-Pehrson <glennrp at users.sourceforge.net> Thu Nov 26 11:49:37 2009 -0600
tree d0ebd1a35a5e3fc0591eefbb33549a4aefd16cfa
parent b2154ccb2bac8193837215d8b9cfaae296dd0c0f

[devel] Add comment about TODO: issue warning if user tries to premultiply

in a nonliner colorspace.

pngread.c

diff --git a/pngread.c b/pngread.c
index 0afec89..96b844f 100644
--- a/pngread.c
+++ b/pngread.c
@@ -425,6 +425,24 @@
    else
       png_warning(png_ptr,
       "Ignoring extra png_read_update_info() call; row buffer not reallocated");
+
+#ifdef PNG_READ_PREMULTIPLY_ALPHA_SUPPORTED
+   if (png_ptr->transformations & PNG_PREMULTIPLY_ALPHA)
+   {
+     /* TO DO:
+      * Check for linear colorspace and if not, issue a warning.
+      * If gAMA is present with gamma == 1.0, it's linear.
+      * If iCCP is present, assume user knows what they are doing
+      *   and it's linear.
+      * If gAMA is present with gamma != 1.0, it's not linear.
+      * If no gAMA or iCCP, assume not linear.
+      * If not linear do:
+      *   png_warning(png_ptr,
+      *      "Premultiply should only be used with gamma == 1.0");
+      */
+   }
+#endif
+
    png_read_transform_info(png_ptr, info_ptr);
 }