Ron Steinke <[EMAIL PROTECTED]> writes:
> Is there any way to extract the alpha channel information from
> a GdkPixbuf (for example, writing it to an array or a grayscale
> pixmap)?
>
You just iterate over the pixels in the pixbuf.
They are arranged like so for a pixbuf with alpha:
RGBA RGBA RGBA RGBA RGBA RGBA RGBA PPP
| rowstride |
| width |
like so for one without:
RGB RGB RGB RGB RGB RGB RGB RGB RGB PP
| rowstride |
| width |
Each letter is a byte,
R = red
G = green
B = blue
A = alpha channel
P = padding (rowstride - width bytes of padding at the end of each
line, it's possible that rowstride == width if so then
no pad bytes are present)
So the red channel at row, column is something like:
pixels[(row * rowstride) + column * bytes_per_pixel]
Where a pixel is an RGB or RGBA group.
Havoc
_______________________________________________
gtk-list mailing list
[EMAIL PROTECTED]
http://mail.gnome.org/mailman/listinfo/gtk-list
