bug#22470: 25.1.50; vc-annotate (HG) does not display changes within one day (colors)

[Dmitry Gutov <dgutov@yandex.ru>]

On 01/26/2016 09:50 PM, Glenn Morris wrote:

> FWIW, I see no difference between current master and emacs-25.
> It also seems self-evident to me that if you've set the date to only
> display at the level of days, you'll only get colouring at the same
> level.
>
> The current vc-annotate behavior for hg seems consistent with eg git.

Both true statements. However, it is possible to both show short dates 
and colorize at the minute resolution, e.g. by asking for a detailed 
date format from the backend program, and then turning those dates into 
short ones when parsing the output. Something to consider for the next 
release, maybe.

> Finally, at a very quick glance that ahg thing seems to colorize based
> on revision number, not on age, which is a different scheme.

I do wonder if aHg's approach is better. The default palette mapping 
doesn't convey to me, personally, any particular information about time. 
I had to glance at the relevant variable and its value to understand 
that red means "new", blue means "old", and green and orange are 
somewhere in between. I'll probably forget this soon enough.

The only way we could make the color intuitive, I think, is by using 
some linear gradient, and then, I fear, the difference in color between 
revisions made on close days might be too small to notice.

Simply showing that these lines of code were produce by the same 
revision, and those and those by two different ones, seems more valuable 
anyway.