Where are the pixels ?

["Christophe Dehais" <christophe dehais gmail com>]

hi list!

So in gtk, a UI is a hierarchy of nested widgets, and the nodes of this "tree" are container elements. Some widgets have an associated GdkWindow, some don't.

What is not clear to me is whether or not a GdkWindow contains the real pixels in some way. Let's assume this scenario: a window is created and its size is computed through size negociation, then a pixel buffer containing all pixels for the window is allocated. So all nested widgets could be NO_WINDOW, they could use the portion of the big pixel buffer corresponding to their position in the window. But this is not the case (for what I understand), and if GdkWindow does allocate the real pixels, I figure there is some sort of over-coverage of the window.

Is there any guru that could explains me how that works or points me a good link to help me clarify this.

The thing is that I plan to write a custom Container widget that composites its childrens and also adds some decorations, and I don't know if I have to claim its parent window for the drawing or if I have to allocate the (possibly multiple) GdkWindow I need.


thanks in advance,
Christophe.