Example of moving colors:

Example creating a Palette from Image:

See T71548 for import add-ons

Example of default palette defined in grease pencil branch (equals to Krita default).

Example of Photoshop default palette imported using new addon of T71548

The palette list does not follow the UI of other lists in Blender, and with new operators we will need more buttons and menus:

That right side looks quite a bit better, I agree.

Small thing but it would also be cool if "Extract Palette" used the same name as the image for the palette.

Example of moving colors

I really would prefer if we can solve this with drag and drop, rather than adding more Up/Down arrow buttons. Not only is it unsightly and ungainly, it's also impractical if you want to move a color swatch 40 places up, you'd have to click that button 40 times!

@Julian Eisel (Severin) Is this another thing that could be handled by your drag and drop system?

In T71705#814106, @William Reynish (billreynish) wrote:

@Julian Eisel (Severin) Is this another thing that could be handled by your drag and drop system?

It will not be handled by D4071, but should be once we extend it for T67893: Drag and Drop for UI elements.

In T71705#814106, @William Reynish (billreynish) wrote:

Example of moving colors

I really would prefer if we can solve this with drag and drop, rather than adding more Up/Down arrow buttons. Not only is it unsightly and ungainly, it's also impractical if you want to move a color swatch 40 places up, you'd have to click that button 40 times!
@Julian Eisel (Severin) Is this another thing that could be handled by your drag and drop system?

this yes! so much i absolutly hate this up/down arrow design +1 to your idea

In T71705#814106, @William Reynish (billreynish) wrote:

Example of moving colors

I really would prefer if we can solve this with drag and drop, rather than adding more Up/Down arrow buttons. Not only is it unsightly and ungainly, it's also impractical if you want to move a color swatch 40 places up, you'd have to click that button 40 times!
@Julian Eisel (Severin) Is this another thing that could be handled by your drag and drop system?

Totally agree, but this is somewhat more general for all list controls in Blender. It's not the main topic of this task, we can implement it when drag and drop to rearrange list items is ready

Great to see palettes getting some care.
From the python API perspective, I would like also to use palettes generally, (specifically with materials/shader editor), but any kind of flexibility would be useful.
At the moment, I had trouble getting a custom palette property to behave, it seems template_palette is limited in scope and not much is exposed within the API and locked down to update parts in the UI it only knows about.
I wouldn't know where to start since Palette and specifically how PaletteColor behaves is quite unique CTRL-click to change, click to update the color picker; but currently only the color picker it knows about.
But since Palette.colors is a collection property itself, perhaps a new template?

template_palette_colors(myproperty.active_palette, "colors", myproperty, "picker_color")

Not to mention the required operators (new, remove, etc)

Just some thoughts. Thanks again.

I don't know if it is possible. But it could be interesting to keep space to be able to display it as an horizontal ribbon.

Such behavior would be as useful for a weight paint palette.

An additional idea:
I remember in another render engine (older version of Appleseed I believe) we were able to define colors, like global colors that can be re-used in shaders.
If we could re-use the colors of a color palette for shaders then we could also just change the color palette to change the colors of all shaders in one go. To get an idea, check: https://youtu.be/DkznarCvPEQ?t=33

In T71705#817743, @rob wesseling (robwesseling) wrote:

An additional idea:
I remember in another render engine (older version of Appleseed I believe) we were able to define colors, like global colors that can be re-used in shaders.
If we could re-use the colors of a color palette for shaders then we could also just change the color palette to change the colors of all shaders in one go. To get an idea, check: https://youtu.be/DkznarCvPEQ?t=33

Yes, currently my addon injects a custom RGB node (named/identifier is unique) into a shader which allows easy access to coloring outside of the shader and to experiment with visual ideas. However palettes at this stage are limited in scope as I mentioned and was only able to resort to this solution which is far from optimal.