Re: cairo built against libpng16

Hey everyone, here's a possible patch. It's the least invasive patch I
could think of.

On Wed, Mar 20, 2013 at 10:16 AM,  <[email protected]> wrote:
> Hi,
>
> simple program attached seems to have different results when
> cairo is built against libpng15 and when it is built against
> libpng16*):
>
> cairo-libpng15-changeroot> ./cairo-fail tmp.png
> PNG image read.
>
> cairo-libpng16-changeroot> ./cairo-fail tmp.png
> Error reading PNG image tmp.png: out of memory
>
>
> The difference between changeroots are really only libpng version:
> @@ -141,9 +141,9 @@ libpcrecpp0-8.31-5.1.x86_64
>  libpcreposix0-8.31-5.1.x86_64
>  libpixman-1-0-0.28.2-3.1.x86_64
>  libpixman-1-0-devel-0.28.2-3.1.x86_64
> -libpng15-15-1.5.14-1.1.x86_64
> -libpng15-compat-devel-1.5.14-1.1.x86_64
> -libpng15-devel-1.5.14-1.1.x86_64
> +libpng16-16-1.6.0-25.1.x86_64
> +libpng16-compat-devel-1.6.0-25.1.x86_64
> +libpng16-devel-1.6.0-25.1.x86_64
>  libpopt0-1.16-20.1.x86_64
>  libppl9-0.11.2-15.1.x86_64
>  libppl_c4-0.11.2-15.1.x86_64
>
> cairo-libpng1{5,6}-changeroot> rpm -q cairo-devel
> cairo-devel-1.12.14-0.x86_64
>
> Petr
>
>
> *) This boiled down when building perl-Cairo against cairo(libpng16).
> 40-th test from CairoSurface.t failed. In turn that means that second
> test from the following doesn't succed.
>
> use strict;
> use warnings;
>
> use Test::More tests => 2;
>
> use constant IMG_WIDTH => 256;
> use constant IMG_HEIGHT => 256;
>
> use Cairo;
>
> my $surf = Cairo::ImageSurface->create ('rgb24', IMG_WIDTH,
> IMG_HEIGHT);
> is ($surf->write_to_png ('tmp.png'), 'success');
>
> $surf = Cairo::ImageSurface->create_from_png ('tmp.png');
> is ($surf->status, 'success');
>
>
> --
> cairo mailing list
> [email protected]
> http://lists.cairographics.org/mailman/listinfo/cairo

-- 
cairo mailing list
[email protected]
http://lists.cairographics.org/mailman/listinfo/cairo

--- cairo-png.c	2012-03-29 12:05:32.000000000 +0200
+++ cairo-png.c	2013-03-30 09:13:50.817181600 +0100
@@ -497,6 +497,20 @@
     }
 }
 
+/* branches into premultiply_data or convert_bytes_to_data depending on color type */
+static void read_user_transform_func (png_structp png, png_row_infop row_info, png_bytep data)
+{
+    switch ((cairo_format_t) png_get_user_transform_ptr (png)) {
+        case CAIRO_FORMAT_ARGB32:
+            premultiply_data (png, row_info, data);
+            break;
+
+        case PNG_COLOR_TYPE_RGB:
+            convert_bytes_to_data (png, row_info, data);
+            break;
+    }
+}
+
 static cairo_status_t
 stdio_read_func (void *closure, unsigned char *data, unsigned int size)
 {
@@ -623,6 +637,9 @@
 
     png_set_filler (png, 0xff, PNG_FILLER_AFTER);
 
+    /* this must be stored before calling png_read_update_info */
+    png_set_read_user_transform_fn (png, read_user_transform_func);
+
     /* recheck header after setting EXPAND options */
     png_read_update_info (png, info);
     png_get_IHDR (png, info,
@@ -643,15 +660,15 @@
 
 	case PNG_COLOR_TYPE_RGB_ALPHA:
 	    format = CAIRO_FORMAT_ARGB32;
-	    png_set_read_user_transform_fn (png, premultiply_data);
 	    break;
 
 	case PNG_COLOR_TYPE_RGB:
 	    format = CAIRO_FORMAT_RGB24;
-	    png_set_read_user_transform_fn (png, convert_bytes_to_data);
 	    break;
     }
 
+    png_set_user_transform_info (png, (void*) format, 0, 0);
+
     stride = cairo_format_stride_for_width (format, png_width);
     if (stride < 0) {
 	surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_STRIDE));