Re: GdkPixmap and GdkPixbuf

[y g <odysseus lost gmail com>]

On 6/6/05, David Necas (Yeti) <yeti physics muni cz> wrote:
> On Mon, Jun 06, 2005 at 03:52:32PM +0100, y g wrote:
> > I already did as I realised that neither is a child of the other as
> > you say. But I am still get seg fault with the following:
> >
> > static void
> > save_image(GtkWidget* widget, gpointer user_data)
> > {
> >  GdkPixbuf* pixbuf;
> >
> >  g_print("Saving image...\n");
> >  //gdk_pixbuf_save(gdk_pixbuf_get_from_drawable(NULL,
> > GDK_DRAWABLE(pixmap), NULL, 0, 0, 0, 0, 600, 400), "temp.bmp", "bmp",
> > NULL);
> >  gdk_pixbuf_get_from_drawable(pixbuf, GDK_DRAWABLE(pixmap), NULL, 0,
>
> Here you pass an uninitialized pointer as pixbuf...
you are referring to pixbuf... yes it is unitiliased and this line
gives me the following when i run it

(canvas:8829): Gdk-CRITICAL **: gdk_pixbuf_get_from_drawable:
assertion `dest->n_channels == 3 || dest->n_channels == 4' failed

if i change the 
> >  GdkPixbuf* pixbuf;
to 
GdkPixbuf* pixbuf=NULL;
I get no warning but still the seg fault.

If I use 
gdk_pixbuf_save(gdk_pixbuf_get_from_drawable(NULL,
GDK_DRAWABLE(pixmap), NULL, 0, 0, 0, 0, 600, 400), "temp.bmp", "bmp",
NULL);

i get again a seg fault. The documentation says: "Destination pixbuf,
or NULL if a new pixbuf should be created." for arg 1.

I also tried to pass a value for colormap with
gdk_drawable_get_colormap(GDK_DRAWABLE(pixmap)) which I dont think it
really matters even if it is NULL.

> >  gdk_pixbuf_save(pixbuf, "temp.bmp", "bmp", NULL);

This one gives me the seg fault.

> ...and again. Don't you get any CRITICAL messages to
> console?

see above
>     pixbuf = gdk_pixbuf_get_from_drawable(NULL, drawable, ...);
>     gdk_pixbuf_save(pixbuf, ...);
>     g_object_unref(pixbuf);

ok i see what you mean... but the following still seg faults... no
warnings this time...


static void
save_image(GtkWidget* widget, gpointer user_data)
{
  GdkPixbuf* pixbuf;

  g_print("Saving image...\n");
  //gdk_pixbuf_save(gdk_pixbuf_get_from_drawable(NULL,
GDK_DRAWABLE(pixmap), NULL, 0, 0, 0, 0, 600, 400), "temp.bmp", "bmp",
NULL);
  pixbuf = gdk_pixbuf_get_from_drawable(NULL, GDK_DRAWABLE(pixmap),
gdk_drawable_get_colormap(GDK_DRAWABLE(pixmap)), 0, 0, 0, 0, 600,
400);
  gdk_pixbuf_save(pixbuf, "temp.bmp", "bmp", NULL);
  g_object_unref(pixbuf);
}



btw thanks for all your help :)