Improve color values storing.

[Gvin]

"Instead of recording the actual color value, 1, 16, 4096, etc, you could store the color as exponent of 2.
2^X where X is from 0 to 15 would give you from white(1) to black(32768) and all the colors between.
To convert back from the color value to X, you could use math.log(color)/math.log(2)"

[theoriginalbit]

indeed, also I suggest that if you're storing colours for the terminal to do math.ceil on the log2, there is no point storing and remembering it as a combination of numbers as the terminal cannot do this. Also doing ceil as opposed to floor will replicate how Java casts a double to an int and make sure that your colours match up with the ones that will be displayed to the screen.

Also if you're writing any screen buffers or anything to file you can combine the background and text colours into a single byte using this conversion method, I'm sure you can figure out how to do it, but here is the code anyway

math.log2 = function(n) return math.log(n)/math.log(2) end

function getCompressedColor( fg, bg )
  local low = bit.band(math.log2(bg), 0xF)
  local high = bit.band(math.log2(fg), 0xF)
  local color = bit.bor( bit.blshift(high, 4), low)
  return color
end

function getUncompressedColor( b )
  low = bit.band(b,15)
  high = bit.brshift(b,4)
  return 2^high, 2^low
end

[Gvin]

Thanks for this storing algorythm! For now we are using the only image format which is capable of storing just pixel's color. But for desktop icons an "icon" file type will be created and we will use your code there.

[theoriginalbit]

No problems. Always happy to help others.