Colorspaces and medium interactions

[Boudewijn Rempt]

> > The paintop and palette are debatable.
> about palettes, we have allready too much palette visibles at the same
> time, and some are useless for the selected layer. I mean the wet
> palette is only usuable with watercolor. 

I did add code to only show the wet palette if the current layer is wet,
and to hide the wet palette if the current layer is not wet. It seemed
to work for me.

> And in the future we will add
> new palettes, one for CMYk, one for LAB (maybe one for YCbCr), one for
> {$NAMEOFYOURBRANDNEWANDCOOLCOLORSPACE}...
> 
> So I think we should have a maximum of four palettes visible at the
> same time, and some might be disabled when needed :
> - HSV
> - the colorspace's palette
> - the predefined palettes
> - history of colors (maybe it can be merged with the predefined palettes ?)
> 
> And of course, in case of watercolors, only the "the colorspace's
> palette" is enabled.
> 
> So, what do you think ?

We got two types of color selector: ordinary color selectors and paint
selectors. The one works for non-media layers, the other type has the
potential to work everywhere.

The ordinary selctors (hsv, gray, lab, cmyk, ycbcr, rgb, swatches,
color wheel, color mixer, image palette) are not colorspace specific:
they work for all non-media colorspaces. Users should have the option
of selecting any number of these and always have them visible whenever a
non-media layer is active. But these selectors could work quite well for
some media layer types (like wet & sticky, which uses hsv natively, where
a hsv color would have no wetness and no stickiness).

Some media colorspaces have selectors that don't do much useful work
when the current layer is not a media layer -- except that it's always
possible to go from a media color to rgb, so they can always be used.

I think we should have three color selectors active by default, and the
rest hidden at the user's option:

* hsv colorwheel (but one with a triangle inside the circle, that one
seems to be preferred by artists above the one with the solid circle) 
* swatches (the palettes palette) 
* a placeholder for media paint selection.

If the layer cannot work with ordinary color selectors, the visible
ordinary color selectors should be disabled, not hidden -- we should
not rearrange the palettes the user has selected. This is where my
solution in 1.5 goes wrong, I try to hide the palette. We should keep
the paint selectors outside the ordinary system of palettes, but instead
keep a list associated with a particular colorspace.

Conversely, if there is a paint selector in the placeholder, we should not 
disable it if the media is ordinary: it can still be used to select color.

We should strive for some more innovative color selectors in 2.0, though.
About a year ago we had an interesting thread about this topic with some
fun links.

Boudewijn