Changing border rendering of terminals

[SquidDev]

This isn't an issue or PR, as I'm not planning to do it anything further about this, but felt it would be useful to demo some work/fiddling I've done:

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CC draws the border margin using the adjacent background colour. This works most of the time, but looks very odd when drawing inverted teletext characters. For instance, here is \x99 rendered with white-on-black and black-on-white:

There was some discussion a long time ago on the original ComputerCraft repo about this, and it has up a couple of times since on CC:T's own issue tracker (e.g. #722).

There, a couple of options were proposed, which I've had a fiddle with implementing. All three screenshots are the result of running the following program (yet, this is very lazy and non-representative):

for i =  1, 19 do
  term.setCursorPos(1, i)
  if i % 2 == 0 then
    term.setBackgroundColor(colours.white)
    term.setTextColor(colours.black)
    term.write("\x8e")
  else
    term.setBackgroundColor(colours.black)
    term.setTextColor(colours.white)
    term.write("\x99")
  end
end

Keep as is

Extend the teletext characters to the edge

Black border

Conclusion

I was originally quite hopeful about "Extend the teletext characters to the edge". This is what I'd suggested in the original issue, but looking at it in practice, I'm less sure about it. It works pretty well for art, and I suspect will be fine for GUIs (as they're fairly blocky), but still feels a little strange for the more complex characters.

I do still prefer the black border in most cases. However, I do agree with Dan's original complaints in dan200/ComputerCraft#242 that it looks a little odd for programs like paint.

[Lupus590]

I like the black border. It'll be mostly the same feel and won't make the border pixels seem like they are extra big in odd dimensions.