Colour by...

[Olly Betts]

On Thu, Feb 06, 2025 at 10:14:01AM +0100, Wilfremed Kane wrote:
> Hi, I am a Survex user since long ago, and wanted to ask about the "colour
> by" options. All the 9 options are ok, but there is one, I think very
> usefull, I miss, or don´t know the way to use it (if it´s available): Have
> the option, in the text file, to determine the colour in each survey
> -*begin / *end- (i.e. *colour green)

That would be mixing how to present the data with the data itself, we
we have tried to avoid doing in Survex.

To see why this sort of approach is limiting, say you want to colour all
the surveys found via particular entrances a different colour so you
add `*colour green`, etc.  However you may also want to be able to view
in aven with the main route through the cave coloured differently to
other surveys.  Embedding colouring information directly in the survey
data means that to have multiple colourings you need to have multiple
copies of the survey data, and then you have the problem of making sure
that the copies of the data remain in step when updates are made.

Having the colouring information as a separate layer to the data means
you could have as many colourings as you wanted.  Also colours could be
set from aven with a GUI colour picker, rather than having to limit to
a short list of named colours or requiring users to enter RGB triplets.

There isn't such a feature currently though I'm afraid.

You can "Colour by Survey" which sets a different colour for each
survey but without any way to control the colours (for the technically
curious, it's implemented by calculating a numeric hash from the survey
name and converting the hash to a colour in HSV-space with the full
range of hue, saturation >= 50% and value 90%).

Cheers,
    Olly