Added methods for converting between rgb and hex color formats

plugin/indent-guides.vim

@@ -1,6 +1,8 @@
 " Author:   Nate Kane <nathanaelkane AT gmail DOT com>
 " Homepage: http://github.com/nathanaelkane/vim-indent-guides
 
+let s:hex_color_pattern = '#[0-9A-Fa-f]\{6\}'
+
 function! s:IndentGuidesToggle()
   let g:IndentGuides_matches =
   \ exists('g:IndentGuides_matches') ? g:IndentGuides_matches : []
@@ -43,8 +45,8 @@ function! s:IndentGuidesDisable()
 endfunction
 
 function! s:IndentGuidesHighlightColors()
-  hi IndentLevelOdd  guibg=#252525
-  hi IndentLevelEven guibg=#303030
+  hi IndentLevelOdd  guibg=#FFFFFF
+  hi IndentLevelEven guibg=#FBFBFB
 endfunction
 
 " Commands
@@ -59,3 +61,83 @@ let g:IndentGuides_debug         = 0
 " Default mapping
 nmap <Leader>ig :IndentGuidesToggle<CR>
 
+"
+" Return hex string equivalent to given decimal string or number.
+"
+" Example: DecToHex(255, 2)
+" Returns: 'FF'
+"
+" Example: DecToHex(255, 5)
+" Returns: '000FF'
+"
+function! DecToHex(arg, padding)
+  return toupper(printf('%0' . a:padding . 'x', a:arg + 0))
+endfunction
+
+"
+" Return number equivalent to given hex string ('0x' is optional).
+"
+" Example: HexToDec('FF')
+" Returns: 255
+"
+" Example: HexToDec('88')
+" Returns: 136
+"
+" Example: HexToDec('00')
+" Returns: 0
+"
+function! HexToDec(arg)
+  return (a:arg =~? '^0x') ? a:arg + 0 : ('0x'.a:arg) + 0
+endfunction
+
+" Example: HexColorToRGB('#0088FF')
+" Returns: [0, 136, 255]
+function! HexColorToRGB(hex_color)
+  let l:rgb = []
+  if matchstr(a:hex_color, s:hex_color_pattern) == a:hex_color
+    let l:red   = HexToDec(strpart(a:hex_color, 1, 2))
+    let l:green = HexToDec(strpart(a:hex_color, 3, 2))
+    let l:blue  = HexToDec(strpart(a:hex_color, 5, 2))
+    let l:rgb = [l:red, l:green, l:blue]
+  end
+  return l:rgb
+endfunction
+
+"
+" Example: RGBColorToHex([0, 136, 255])
+" Returns: '#0088FF'
+"
+function! RGBColorToHex(rgb_color)
+  let l:hex_color  = '#'
+  let l:hex_color .= DecToHex(a:rgb_color[0], 2) " red
+  let l:hex_color .= DecToHex(a:rgb_color[1], 2) " green
+  let l:hex_color .= DecToHex(a:rgb_color[2], 2) " blue
+  return l:hex_color
+endfunction
+
+"
+" Example: HexColorBrighten('#000000', 0.10)
+" Returns: '#191919'
+"
+function! HexColorBrighten(color, percent)
+  let l:rgb = HexColorToRGB(a:color)
+  let l:rgb_brightened = []
+  for decimal in l:rgb
+    call add(l:rgb_brightened, float2nr((255 - decimal) * a:percent))
+  endfor
+  return RGBColorToHex(l:rgb_brightened)
+endfunction
+
+"
+" Example: HexColorDarken('#FFFFFF', 0.10)
+" Returns: '#E5E5E5'
+"
+function! HexColorDarken(color, percent)
+  let l:rgb = HexColorToRGB(a:color)
+  let l:rgb_darkened = []
+  for decimal in l:rgb
+    call add(l:rgb_darkened, float2nr(decimal * (1 - a:percent)))
+  endfor
+  return RGBColorToHex(l:rgb_darkened)
+endfunction
+