[CREATE] OpenRaster specification: updates to support masking

[Boudewijn Rempt]

On Tue, 28 Jan 2014, Andrew Chadwick wrote:

> It's worth noting that there are probably only a small number of the
> compositing modes that make sense for a painting app:
>
> - source-over for general work
> - destination-in for making masks where you draw the void
> - destination-out for making masks where you trim off the unwanted
> edges (unusual, but it's more efficient to render ☺)
> - source-atop for making coloured textures over the tops of things
>
> Of the others, {destination, copy, clear} are pointless for getting
> things done. As for source-{in, out} for making masks, sure they can
> be used, but using their destination-{in, out} equivalents over the
> top in an isolated <stack/> makes for a simpler stacking structure
> when you find yourself wanting a group of layers you want to mask as a
> whole.

Yes -- well, as I understand it, this means we will have to do the layer 
composition in two steps, and that touches the core of our codebase. But 
maybe I'm wrong.

>> On the topic of openraster, I want to bring something up that was discussed before, but I don't remember the resolution:
>>
>> I'd like to add a png of the rendered image to the zip file. For Qt, I created a qimagio plugin that can show ora files, but it actually uses all of Krita to render the file -- and that is both dangerous and takes a lot of time.
>
> Isn't that the idea behind mergedimage.png?
> http://www.freedesktop.org/wiki/Specifications/OpenRaster/Draft/FileLayout/
>
> We could bump it up to a MUST, but that might need a new spec version.

I'd like a bump then -- it would make viewers so much easier.

Boud