Change diagonals concepts

[PhMajerus]

Currently, the ╱ (U+2571), ╲ (U+2572), and ╳ (U+2573) diagonals are using a 2-2-2-1-2-2-2 pattern for their slopes.
While this looks the most natural when they are seen individually, those diagonals characters are designed to join together to create longer diagonal lines and shapes, and when they are combined, because of the 1px overflow/overhang, the resulting pattern combines two consecutive segments of 2 pixels.
The final line pattern therefore ends up being …2-2-1-2-2-4-2-2-1-2-2-4…. As you can see, this pattern is not regular, and the mix of 1 and 4 makes the line wiggly instead of straight.

I really like the idea of the 1px overflow/overhang to merge the pixels when characters are touching horizontally, so this proposal contains an improvement to make the lines straighter but keeps the original concept.
I propose to use the pattern 1-2-2-3-2-2-1 pattern instead. While this looks less regular at first glance when taking it individually, observe how it combines when several of those characters follow each other. The final line pattern ends up being …2-2-3-2-2-2-2-2-3-2-2-2-2-2-3…, creating a line as straight as it can be achieved with an odd number of pixels.

These three characters are also now complemented by 4 different cusps (like < > v ^) in Symbols for Legacy Computing (seen below as Diagonals group 1), and using the updated pattern makes continuity of all these pieces fit much more nicely together. My PR #144 already uses that proposed design for those 4 new characters.

I didn't want my first PR to introduce changes to existing glyphs, but if you're open to those changes, I would submit them.

[the-moonwitch]

I like this! My only concern is about how it'll look if the characters are used in e.g. editor status lines.

[PhMajerus]

These 3 diagonals, and the 4 new ones added in Unicode 16, are part of the box drawings, like the table lines and corners. Their purpose is to connect to make lines. If you try echo "Cozette" | figlet -f slant | sed 'y|/\\|╱╲|', here are the results…

With the current box drawings diagonals:

And with my proposed design:

I think having them join properly is the most important. Do you have any application in mind that uses them in a status bar? It shouldn't break it, and they still reach the same pixels at their ends. It will just look slightly less natural by itself while greatly improving their intended design as pieces of longer diagonal lines. We're basically just slightly correcting their angle.

Edit: The rendering can be even further improved by using the following command: echo "Cozette" | figlet -f slant | sed 'y|/\\_|╱╲▁|':

[the-moonwitch]

Actually, yeah, you're right - status bars generally use customizable separators, and we should prioritize the characters looking right in their intended purpose (box drawing) over usecases where they can be easily replaced with something else.