Re: [gtkmm] Why gdk::Pixbuf makes every image to 24bit or 32 bit ?

[Anastasios Bassoukos <abas aix meng auth gr>]

On Tue, 2004-02-24 at 10:34, Ramachandra Putti wrote:
> Hi ,
>    I am currently working on a Image Processing tool. I am using 

Why? Aren't there enough already?

> Gnome::Canvas to display the image with the help of pixbuf.

Hell, you won't be doing any heavy-duty image displaying then, correct? 

>    The situation in which I am strucked is on creating Pixbuf from
> file 
> or data , even though I have 1 bit image, gdk:: pixbuf will
>    convert it into 24 bit image or 32 bit image.
> 
>         Glib::RefPtr<Gdk::Pixbuf>  pixBuf;   
>         pixBuf = Gdk::Pixbuf::create_from_file( fileName );
>   
>         Glib::RefPtr<Gdk::Pixbuf> newpicture;
>          
>         newpicture = Gdk::Pixbuf::create(Gdk::COLORSPACE_RGB, true, 1,
> width, height);   //  This to be checked ???
>         newpicture =  Gdk::Pixbuf::create_subpixbuf (pixBuf, ax1, ay1,
> width, height);
>    
>           I have to implement one feature which changes 24 bit image
> to 
>  1 bit , 8 bit , 32 bit and vice versa. How can I do that ?

Have a look at the Gimp source.
[flamebait mode=off] You have to understand that *you* will need to take
care of the internal representation of images to 

>      Question is why gdk::pixbuf changes every image into 24 or 32 bi
> t ? 
> don't it makes image manipulation slow too ?

No. It makes for less code, as it makes the image manipulation routines
simpler. Also, note that pixbufs are only one step removed from the
display, which is probably not abstract enough for your needs.

>  Any help will be appreciated.

You could use Gdk::Images, they do implement different bit-depths, but
then you will need to implement zooming and clipping, and that's why you
have a canvas, correct?

> Regards ,
> Ramachandra

HTH,
Tassos

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