Add support for setting indicator color

[almarklein]

• [x] Add color arg, eg VolumeSlicer(... color='red').
• [x] Draw a rectangle around the image in that color. (But only when other slicers are present.)
• [x] Other slicers draw indicators in that color.
• [x] Indicators are now across the image.
• [x] Decide on way to display the color of the current slicer. -> corners with slightly thicker lines.
• [x] What should the default color be -> different color for each axis based on a good colormap (e.g. D3).
• [x] Refactor to use one store less (combine "index" and "pos" into "state).
• [x] Also include (rate limited) axis ranges, so that the indicators can be drawn correctly when zoomed in.
• [x] Renamed some fields in the info store to avoid confusion with shape, sampling and origin.
• [x] Slicer colors are taken from a plotly colormap.
• [x] The create_overlay_data() method samples default colors from the same colormap.
• [x] If a colormap is given to create_overlay_data(), the first element is used where mask is 1 (was 0).
• [x] Update slicer_with_3_views to show slicer view ranges in the 3D figure.

• [x] Find actual figure size via gd._fullLayout.width / height?

[nicolaskruchten]

Hmm the border is a bit intense... I wonder if maybe just having the corners highlighted would be enough? Like an indicator line along both sides of every corner for 20 pixels or something?

[almarklein]

Hmm the border is a bit intense...

Yeah, I played a bit with slimmer lines, but certain colors would be barely visible then. I'll try the corners-thing.

[emmanuelle]

Maybe a matter of color and taste, but I'm fine with lines as they are now. And it helps a lot with the navigation, love this feature!!

[emmanuelle]

What do you think @surchs? Are lines too thick or ok? We need more opinions :-).

[almarklein]

Added another possible approach to the top post. edit: And also Nicolas' suggestion.

[surchs]

Nice, this looks very cool and makes it easier to use! I like the lines as well with the current thickness. Maybe to denote the individual axis graphs, we could just use a thick line on the bottom, rather than a complete border. And maybe this "indicator" line should be optional and default to hidden when no slicer colour is defined (or they all default to turquoise).

[nicolaskruchten]

I think this is looking pretty great! The corner indicators could be a little smaller perhaps, and I personally preferred the "outer tick" style of indicators for the other two, that way they don't occlude the figure, but that's maybe just a personal style thing.

It would be awesome to get these indicators somehow reflected in the 3d view as well if possible in the example with the 3d plot :)

[almarklein]

@nicolaskruchten

[nicolaskruchten]

zomg that's cool

[almarklein]

Ready for review.

The corner-indicators are now actually square, and have the same size in each view targeting the same volume.

Quite a few changes, I also renamed some variables, and refactored a bit.

[almarklein]

Hold on - After discussion with @nicolaskruchten I'm going to try changing how we define the "indicator ranges".