On 6/16/06, Frédéric <[EMAIL PROTECTED]> wrote:
On Friday 16 June 2006 21:41, Michael Thaler wrote:

> Can someone explain to me why the code iterates over all pixels in a
> region and then over all regions and not just over all pixels in a
> layer? What are PixelRegions actually, what are they used for and why
> they are needed here? (I had a look at
> http://developer.gimp.org/api/2.0/app/app-pixel-region.html but this
> doesn't explain what they are for)

As far as I understand, a region can be what you want; it can cover a
entire layer, or just a small part (like the preview for plug-ins. Have a
look here:


When you have initialized a region, you can access it pixel by pixel, row
by row, or tile by tile, depending what you want to do (I guess each
method has advantages, according to the filter you want to write).

I think it's important to mention that if your algorithm supports it,
using pixel_regions_process () or the new gimp_rgn_iterate() functions
is by far the easiest and best performing way to use pixel regions.
If you use them on more than one pixel region, the regions are
"registered" such that through each iteration, all of the regions are
pointing to the same part.  This makes operations like copying from
one layer to another a snap to write.  You might want to look at
tile.c or threshold_alpha.c in the plug-ins/common directory for some

Gimp-developer mailing list

Reply via email to