ColorChooser : Maintain hue and saturation at zero

[ericmehl]

This changes the behavior of the color chooser somewhat, so that setting the saturation to zero does not cause the hue to be reset to zero, and setting the value to zero does not cause the hue and saturation to be reset to zero.

I'm not super-excited about storing and syncing the HSV color to the RGB color, but I think it's better than the alternatives. We need some way of knowing what the HS value should be if we're deciding not to set it, and that's now coming from the synchronized self.__colorHsv variable.

I also looked at converting the whole ColorChooser to use HSV values internally and not store RGB. That worked also, but as we talked about, it also has the side effect that ColorChooser.setColor( x ).getColor() != x because of floating point round off, which does not seem like the right way to go.

Checklist

• I have read the contribution guidelines.
• I have updated the documentation, if applicable.
• I have tested my change(s) in the test suite, and added new test cases where necessary.
• My code follows the Gaffer project's prevailing coding style and conventions.

[johnhaddon]

Thanks Eric - very nice to have this fixed. Couple of comments inline - the latter of which is definitely worth addressing I think. And we also need to target the PR to 1.4_maintenance1.
Cheers...
John

[johnhaddon]

Thanks Eric! And sorry, one last round of comments from me. The "not public" one is definitely important - see what you think about the others...
Cheers...
John

[ericmehl]

I pushed up a fix to the previous fix (squashed into the fixup in f2fd617) and all seems to be working well in practice. Ready for a new look!

[johnhaddon]

Thanks Eric! I've squashed in the fixups and merged.