gdip-pixbuf-loader r11 - in trunk: . src

[doml svn gnome org]

Author: doml
Date: Mon Feb 18 17:27:13 2008
New Revision: 11
URL: http://svn.gnome.org/viewvc/gdip-pixbuf-loader?rev=11&view=rev

Log:
2008-02-18  Dominic Lachowicz <domlachowicz gmail com>

	* src/io-gdip.c (gdk_pixbuf__gdip_image_stop_load): Un-premultiply alpha

Modified:
   trunk/ChangeLog
   trunk/src/io-gdip.c

Modified: trunk/src/io-gdip.c
==============================================================================
--- trunk/src/io-gdip.c	(original)
+++ trunk/src/io-gdip.c	Mon Feb 18 17:27:13 2008
@@ -171,6 +171,7 @@
 		{
 			ARGB pixel;
 			guchar * channel;
+                        guint8 alpha;
 
 			pixel = io_gdip_bitmap_get_pixel (bitmap, x, y);
 			channel = (guchar*) &pixel;
@@ -178,13 +179,16 @@
 			if (y > 0) cursor += y * x * n_channels;
 			else cursor += x * n_channels;
 
-//			cursor += y * rowstride; //Something wrong here rowstride=1604
-
-
-			cursor[0] = channel[1];
-			cursor[1] = channel[2];
-			cursor[2] = channel[3];
-			cursor[3] = channel[0];
+                        /* un-premultiply alpha */
+                        alpha = (pixel & 0xff000000) >> 24;
+                        if (alpha == 0) {
+                                cursor[0] = cursor[1] = cursor[2] = cursor[3] = 0;
+                        } else {
+                                cursor[0] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+                                cursor[1] = (((pixel & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha;
+                                cursor[2] = (((pixel & 0x0000ff) >> 0) * 255 + alpha / 2) / alpha;
+                                cursor[3] = alpha;
+                        }                        
 		}
 	}