ColorProperty: Use ColorProperty instead of ListProperty for color property

[pythonic64]

For all color properties except:

• GestureSurface.color
• Label.outline_color
• Label.disabled_outline_color

as for those properties format rgb is used and additional changes are needed to enable using of ColorProperty

[pythonic64]

Should be merged after #6917 .

[matham]

It looks ok, although it makes me nervous to change code on masse like this. I'd want at least one other person to look it over.

One thing, it would be ideal if you could add versionchanged tag for these properties to say it was changed to a color property.

[pythonic64]

Added versionchanged tag.

Regression problem I can see is setting of individual components for color (with __setitem__) or setting of slice, but those are rare cases in my opinion.

[matham]

Regression problem I can see is setting of individual components for color (with setitem) or setting of slice,

How do you mean? ColorProperty still uses a list to represent the color, doesn't it?

[pythonic64]

Setting like

obj.color[0] = 0.5

won't dispatch event that color changed.

[matham]

won't dispatch event that color changed.

Oh, that's definitely bad. I wouldn't assume it's not a common usage, I'm pretty sure I used that with slicing. But even if it's not common, we can't break it like that.

The solution is to change ColorProperty to use a ObservableList instead of a normal list https://github.com/kivy/kivy/blob/master/kivy/properties.pyx#L710.

[pythonic64]

How can we ensure that iterable of 3 or 4 components are used when setting a slice?
Example:

obj.color[:] = [0.1, 0.2, 0.3, 1.0, 1.0]

ColorProperty should ensure that 4 components or 3 with 1.0 alpha by default.

[matham]

How can we ensure that iterable of 3 or 4 components are used when setting a slice?

The current implementation has the same problem though!? That would be user error and we don't have to protect against it. Trying to protect against that would make things much more complicated.

[pythonic64]

Ok. I'll add a note to ColorProperty about slicing and that should cover it.

[matham]

Cool. Although it's not just slicing. Presumably doing obj.color.extend([1, 2, 3, 4, 5, 6]) would also be a problem.

[pythonic64]

Added note under versionchanged tag because indexing and slicing are now supported. See #6930.

[pythonic64]

@matham Are we waiting for another developer to approve or I can squash and merge?

[matham]

Yeah, because it's such a large change I'd like it if someone like @tshirtman would also approve.

[tshirtman]

looks good to me, as long the change to ColorProperty now means we can use it exactly like any ListProperty would be in this context, yes it changes quite a few pieces of the code, but the change every time is pretty trivial.