Re: Gdk::Pixbuf::create_from_data strange behaviour

[Aurélien KAMEL <aurelien kamel gmail com>]

Thanks both Paul and Jonathon for your answers, I appreciate.

Having two objects which share the same pixel array (and so avoid  
updating the pixbuf manually) can be a good thing for my application  
so my problem is going to be a kind of solution if I modify some things.

Thanks to you I'm a bit more aware of how works a Pixbuf when created  
with create_from_data().

Good evenning,
Aurelien (the guy with his bad english :)

Le 10 mai 06 à 20:56, Jonathon Jongsma a écrit :

> On 5/10/06, Aurélien KAMEL <aurelien kamel gmail com> wrote:
> > Hello,
> >
> > I'm creating a pixbuf from a pixel array like this :
> >
> > Glib::RefPtr<Gdk::Pixbuf> =
> >         Gdk::Pixbuf::create_from_data 
> > (array,Gdk::COLORSPACE_RGB,false,
> > 8,sizeX,sizeY,sizeX*3);
> >
> > The problem is that if after this call to create_from_data() I do a
> > free() on the pixel array then the program crash when I try to use
> > the Pixbuf... If I don't free() the pixel array then I can use my
> > Pixbuf normally, display it etc.
>
> I believe this is intentional.  Consider the use case where you have a
> pixel array that is created or managed by a different object, and you
> want to use that data with a Gdk::Pixbuf.  You want these two
> different objects to use the exact same data source so that, for
> example, when the other object modifies some of the raw data, it's
> also updated in the Pixbuf.  At least that's my understanding of this
> function.
>
> > And, I see that there is a create_from_inline() which take as
> > argument a bool copy_pixels ? Can I use this function (how?) so that
> > I can free() the pixel array after Pixbuf was created ?
>
> It looks to me like this function expects the data formatted in a
> slightly different way than create_from_data() (see
> http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/ 
> classGdk_1_1Pixbuf.html#aac78677d8310866334827db2a9f753c).
> If you can get your data into that format, you might be able to use
> it.
>
> Otherwise, do you need to free the pixel array right away?  Maybe you
> could use the create_from_data() function that takes a SlotDestroyData
> argument.  That way you don't have to worry about when to free it
> because it will be automatically freed when the pixbuf is destroyed.
>
> Jonner