[gtkmm] Pixbuf memory management

[Jussi Pakkanen <jpakkane yahoo com>]

Hi

I have been porting a program to gtkmm2. So far
everything has been nice. However when I tried to use
pixbufs I ran into some trouble.

The lifetime issues of pixbufs is very murky, both in
Gtk+'s and gtkmm's documentation. In my case, I have
several small images in a nonstandard format. These
images need to be shown occasionally. I think that the
best way to do this is to code a function that
transforms the images to a temporary RGB pixel array.
Then I create a pixbuf using
Gdk::Pixbuf::create_from_data().

The problem is this: when and who should free the
temporary array of RGB values I constructed? The
documentation seems to implicate that creating the
pixbuf does not make a copy of the data. This seems a
little counterintuitive. I just want to create a
pixbuf from my temporary data and then delete it
without affecting the pixbuf.

Does create_from_data() make a copy of the image data
or not? If not, is there a more elegant way around
this than making a pixbuf without a destroyer
function, duplicating it with copy() and then deleting
the first pixbuf and the temporary array?

PS I assume that create_from_data() expects the data
to be in the format R,G,B,R,G,B,R,G,B... without alpha
channel and R,G,B,A,R,G,B,A,R,G,B,A... with it. Is
this correct?


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