Re: gdk_pixbuf_composite leaves artifacts in the dest pixbuf, if, dest_x is > 0. Help please?

[Todor Todorov <ttodorov gmx net>]

Thank you so much for the answer!

The correct use (yours) is

gdk_pixbuf_composite( interm, result, xOffset, 0, width, height, xOffset, 0, 1.0, 1.0, GDK_INTERP_NEAREST, 
255 );

as opposed to (mine)

gdk_pixbuf_composite( interm, result, xOffset, 0, width, height, /* !!! */ 0, 0, 1.0, 1.0, 
GDK_INTERP_NEAREST, 255 );

I didn't quite realize that I need to apply the destination displacement 
as scaling offset as well - the documentation, or rather the nice 
picture showing the use of the function in the GdkPixbuf reference, did 
not explain the relationship between step 1 and step 3 in the transition 
... It is a nice picture though :-)

Thanks again for the help.

Best regards,

Todor

On 11/11/2009 03:20 AM, Tadej BorovÅak wrote:
> Hello.
>
> Composing function is a bit hard to use at first. Your code should
> probably look something like this (I haven't tested it).
>
> ---- CODE ----
> gchar *imgSrcName;
> GdkPixbuf *src, *interm, *result;
> guint width, height, xOffset, yOffset;
> int i = 0;
> ...
> src = gdk_pixbuf_load_from_file_at_scale( imgSrcName, 128, 128, TRUE, NULL );
> result = gdk_pixbuf_new( GDK_COLORSPACE_RGB, TRUE,
> gdk_pixbuf_get_bits_per_sample( src ), 128, 128 );
>
> interm = gdk_pixbuf_apply_embedded_orientation( src );
> gdk_pixbuf_unref( src );
> width = gdk_pixbuf_get_width( interm );
> height = gdk_pixbuf_get_height( interm );
> ...
> while ( i<  2 )
> {
>         gchar *save;
>
>         gdk_pixbuf_fill( result, 0xffffff00 );
>         xOffset = i++ * ( 128 - width ) / 2;
>         yOffset = i++ * ( 128 - height ) / 2;
>         gdk_pixbuf_composite( interm, result, xOffset, yOffset, width,
> height, xOffset, yOffset, 1.0, 1.0, GDK_INTERP_NEAREST, 255 );
>
>         save = g_strdup_printf( "test%d.jpg", i );
>         gdk_pixbuf_save( result, save, "jpeg", NULL, "quality", "100", NULL );
>         g_free( save );
> }
> gdk_pixbuf_unref( interm );
> gdk_pixbuf_unref( result );
> ---- CODE ----
>
> BTW, gdk_pixbuf_unref is deprecated in favor of g_object_unref, since
> GdkPixbuf is derived from GObject now.
>
> Tadej
>
>