I deal a lot with hex color codes in CSS. One thing I occasionally need to do is invert color codes. Normally this is something I could Google for, but I wanted a solution that didn’t requiring constant reference.
My favorite text editor, Textmate, has a powerful automation system. I can write mini scripts in whatever language suitable and take advantage of the power of Unix shell scripting to execute them. From Googling, I learned enough ruby to learn that this:
printf("#%06X", 0xFFFFFF - STDIN.gets.gsub(/^#/,"").hex )
Will invert a hex color from standard input. What it’s doing is fairly simple. It’s using printf to print a formatted string. %06X means it should zero-fill the resulting string with up to six zeros, the same way a hex color string is (e.g. we write 0000FF and not FF to mean ‘blue’). The rest is simple subtraction. We take FFFFFF, the hex code for white, and subtract the input from STDIN and arrive at the inverse of what we started.
Now to add this to TextMate we open Automation|Run Command|Edit Commands... and create a new command:
echo $TM_SELECTED_TEXT |ruby -e 'printf("#%06X", 0xFFFFFF - STDIN.gets.gsub(/^#/,"").hex )'
This echo’s whatever is selected and pipes it to the ruby script. We set the command to input selected text and replace the selected text on output. Furthermore we can bind it to a keystroke. I chose Control-Alt-I, as it is unused on my system.
Voila, I can highlight any hex code and instantly invert it.
To keep this on one line, I neglected a few friendly features. One is interpreting 3-digit hex colors (e.g. #ccc), and the other is knowing whether or not to place the # in the result. If you can come up with an elegant solution, please post it below. Otherwise I hope this helps.