[gdk-pixbuf] ico: Fix area-updated coordinates

[Bastien Nocera <hadess src gnome org>]

commit ebcd488cc433be8bc00ccb8e820597de4388108e
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Dec 29 16:21:37 2016 +0100

    ico: Fix area-updated coordinates
    
    When the icon is constructed bottom to top, the y coordinates were
    incorrectly computed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=581484

 gdk-pixbuf/io-ico.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/gdk-pixbuf/io-ico.c b/gdk-pixbuf/io-ico.c
index 9448619..9815dcf 100644
--- a/gdk-pixbuf/io-ico.c
+++ b/gdk-pixbuf/io-ico.c
@@ -881,9 +881,15 @@ static void OneLine(struct ico_progressive_state *context)
          
 
        if (context->updated_func != NULL) {
+               int y;
+
+               y = context->Lines % context->Header.height;
+               if (context->Header.Negative == 0 &&
+                   context->Lines < context->Header.height)
+                       y = context->Header.height - y;
                (*context->updated_func) (context->pixbuf,
                                          0,
-                                         context->Lines % context->Header.height,
+                                         y,
                                          context->Header.width,
                                          1,
                                          context->user_data);