WIP: Further improvements to Git Graph

[zeripath]

• Restructure to extract out Flow generation and allow flows to be associated with commits
• Provide an alternative flow generation that prefers trunks
  • algorithm
  • provide a switch
• Provide a default palette to make colors more predictable
• Provide a way of pinning colors over page turns.
  • When assigning colors to flows allow colors to be preassigned
  • Pass the colors on page turn
• It would be helpful if you could highlight commits/flows on mouseover of flows/commits

Signed-off-by: Andrew Thornton art27@cantab.net

[silverwind]

Provide a way of pinning colors over page turns.
Pass the colors on page turn

This seems like a overly complicated approach. I would use something like https://github.com/zenozeng/color-hash to convert a branch name to a static color. On dark theme (use isDarkTheme()) add a higher lightness than on light theme to ensure sufficient contrast over the background.

I also once made a personal fork of color-hash with an option to specificy min/max lightness and saturation, maybe it'll be needed.

Also see #10217 (comment)

[zeripath]

Git branches are misnamed they are simply named commits - once a commit has been made there is no way to determine which of the parents had the branch name, or of any of them had it.

It would be lovely if we could apply fixed names to flows. There is no such naming system possible.

So as far as I can see this is the simplest approach.

[zeripath]

Even determining whether to create a new flow or end a flow is not even fixed:

Given the following glyphs:

 |    or    \|
/|           |

Which flow continues, which flow creates a new flow?

If we want pinning we will also have to apply #12142 - fortunately that appears to have no detrimental effects on my test machine although it definitely seems wasteful.

[zeripath]

But I think you're right in another way flow determination will have to go to the server for the same reason as #12142

[silverwind]

Regarding colors, I just suggest a static list of 16 (or more if you like, but the more there are, the less distinction is possible) predefined colors, see #10217 (comment). It's the simplest way and we can tweak the colors to always look good.