Painting on a temporary layer

Boudewijn Rempt boud at
Sat Sep 25 15:55:39 CEST 2004

On Saturday 25 September 2004 15:44, Bart Coppens wrote:
> Quoting Boudewijn Rempt <boud at>:
> > This is for painting with filters, right? Not for applying filters in
> > general?
> Yes, it's for painting with filters.

I really like it that we have that feature -- it's pretty original, as far
as I know only Photogenics has it. It's at its best with the big cursors you
can make with autobrush.

> Yes, that's what I feared. Because of that, I made the whole feature
> optional and set to off by default. So only the paint tools that really
> need it can use it.

There must be lots of possibilities to make the whole process more efficient. 
What I wonder, though, is why it makes a difference when we already have a 
temporary layer in the paint ops. If I understand it correctly we have
always used the following

1 layer
2 take data from layer, filter it, put in dab using brush shape as mask
3 composite dab with layer

Which with temp layers becomes:

1 original layer
2 create temp layer
3 take data from original layer, filter it, put in brush shape on dab.
4 composite dab with temp layer
5 composite temp layer when done.

I think I see... You shouldn't take already filtered data in step 3, but the
original data. But even after step 3 in the original process, we still have 
the original unfiltered data. But it's hidden in the undo information. If we 
had a way of taking data during paint from the layer state before we started 
painting, instead of from the affected tiles, we wouldn't need a temporary 

That would be a lot harder, though, and prone to mistakes. Still, it might be 
something to give a try if your current approach (which has the advantage of
being conceptually cleaner and easier to understand) turns out to be too slow
with big images (say > 1600x1200).

> > KisView::updateCanvas() ?
> I'll try that, thanks for the idea.

I took a look at the code KisView uses to add a new layer, and that seemed
one of the significant differences.

Boudewijn Rempt | "Geef mij maar zuurtjes."
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