Re: More problems with gdk-pixbuf [UPDATE]

[Owen Taylor <otaylor redhat com>]

Loban Rahman <loban@enigma.caltech.edu> writes:

> Thanx Jeff, it works now. Here is the patch for the package, if anyone
> can please commit it (unless this is the wrong solution).

[...]
 
> cvs server: Diffing .
> Index: gdk-pixbuf-util.c
> ===================================================================
> RCS file: /cvs/gnome/gdk-pixbuf/gdk-pixbuf/gdk-pixbuf-util.c,v
> retrieving revision 1.6
> diff -r1.6 gdk-pixbuf-util.c
> 129,130c129
> < 			  (double) (dest_x - src_x),
> < 			  (double) (dest_y - src_y),
> ---
> > 			  0, 0,

Well, it's on the right track, but not quite the right solution.
(Also note, that you should also use unified diffs (cvs diff -u)
diffs like this aren't particularly useful since there is
no context.)

The problem isn't actually in- gdk_pixbuf_copy_area() - it is
using gdk_pixbuf_scale() correctly as documented. The problem
is in gkd_pixbuf_scale() itself, which doesn't handle the 
dest_x and dest_y parameters correctly. 

The patch I'm going to commit is appended below - I do need to
do a bit more testing first. (The hunk for pixops.c is an
unrelated bug that I came across while looking for the real
one.)

Thanks for coming up with a good test case - it was very useful
in tracking this down.

                                        Owen
 
? lines
Index: gdk-pixbuf-scale.c
===================================================================
RCS file: /cvs/gnome/gdk-pixbuf/gdk-pixbuf/gdk-pixbuf-scale.c,v
retrieving revision 1.4
diff -u -r1.4 gdk-pixbuf-scale.c
--- gdk-pixbuf-scale.c	2000/04/11 07:03:24	1.4
+++ gdk-pixbuf-scale.c	2000/04/22 04:57:18
@@ -68,7 +68,8 @@
   offset_y = floor (offset_y + 0.5);
   
   pixops_scale (dest->pixels + dest_y * dest->rowstride + dest_x * dest->n_channels,
-		-offset_x, -offset_y, dest_width - offset_x, dest_height - offset_y,
+		dest_x - offset_x, dest_y - offset_y, 
+		dest_x + dest_width - offset_x, dest_y + dest_height - offset_y,
 		dest->rowstride, dest->n_channels, dest->has_alpha,
 		src->pixels, src->width, src->height,
 		src->rowstride, src->n_channels, src->has_alpha,
@@ -118,7 +119,8 @@
   offset_x = floor (offset_x + 0.5);
   offset_y = floor (offset_y + 0.5);
   pixops_composite (dest->pixels + dest_y * dest->rowstride + dest_x * dest->n_channels,
-		    -offset_x, -offset_y, dest_width - offset_x, dest_height - offset_y,
+		    dest_x - offset_x, dest_y - offset_y, 
+		    dest_x + dest_width - offset_x, dest_y + dest_height - offset_y,
 		    dest->rowstride, dest->n_channels, dest->has_alpha,
 		    src->pixels, src->width, src->height,
 		    src->rowstride, src->n_channels, src->has_alpha,
@@ -180,7 +182,8 @@
   offset_y = floor (offset_y + 0.5);
   
   pixops_composite_color (dest->pixels + dest_y * dest->rowstride + dest_x * dest->n_channels,
-			  -offset_x, -offset_y, dest_width - offset_x, dest_height - offset_y,
+			  dest_x - offset_x, dest_y - offset_y, 
+			  dest_x + dest_width - offset_x, dest_y + dest_height - offset_y,
 			  dest->rowstride, dest->n_channels, dest->has_alpha,
 			  src->pixels, src->width, src->height,
 			  src->rowstride, src->n_channels, src->has_alpha,
Index: pixops/pixops.c
===================================================================
RCS file: /cvs/gnome/gdk-pixbuf/gdk-pixbuf/pixops/pixops.c,v
retrieving revision 1.10
diff -u -r1.10 pixops.c
--- pixops/pixops.c	2000/04/11 07:03:25	1.10
+++ pixops/pixops.c	2000/04/22 04:57:21
@@ -93,7 +93,7 @@
 
   for (i = 0; i < (render_y1 - render_y0); i++)
     {
-      const guchar *src  = src_buf + ((i * y_step + y_step / 2) >> SCALE_SHIFT) * src_rowstride;
+      const guchar *src  = src_buf + (((i + render_y0) * y_step + y_step / 2) >> SCALE_SHIFT) * src_rowstride;
       guchar       *dest = dest_buf + i * dest_rowstride;
 
       x = render_x0 * x_step + x_step / 2;