Re: Crash when calling Gdk::Drawable::draw_pixbuf

[Falk Schilling <falk schilling gmx net>]

Hallo Daniel,

thanks for your reply.

Daniel Elstner schrieb:
>> m_drawable = Gdk::Drawable::create();
> 
> That looks odd.  If that create() method does indeed exist, I have no
> idea what it would possibly do.  Gdk::Drawable is an abstract base
> class. :-)

Well, that explains a few things, e.g. some missing constructor methods
for Gdk::Drawable (compared with other classes). Since this class method
returns a Glib::RefPtr<Gdk::Drawable> I assumed that this is the way of
creating objects. The documentation unfortunately lacks some information
at this point, what this is used for.

>> Maybe I have somewhere overlooked something in the documentation, but I
>> assume that this is the right way to instantiate an Gdk::Drawable object.
> 
> I'm surprised that it is possible at all.  You want to instantiate a
> Gdk::Pixmap, Gdk::Bitmap or Gdk::Window object, I think.
> 
> Also, are you sure Gdk::Image is really what you want to use?  This
> stuff all maps directly to X11 primitives...

Well, I don’t want to use Cairo for just drawing simple pixels. I indeed
don’t need stuff like arcs, lines or whatever else; I want to read
pixels out of an image, process the values and write the result into
another image. Purely and simple pixel operations.

Ok, you suggest to take Gdk::Pixmap for this stuff. Well, how do I
convert the Gdk::Pixbuf into a Gdk::Pixmap?

Greetings,
Falk Schilling