Extract method for clarity.

README.mkd

@@ -61,15 +61,45 @@ You may want to add mappings for these if you use them often.
 If you want to define your own highlights, you can turn off vim-gitgutter's with `let g:gitgutter_highlights = 0` in your `~/.vimrc`.
 
 
+### Customisation
+
+* The sign column's colours
+* The signs' colours
+* The signs' symbols
+* Line highlights
+* Whether or not vim-gitgutter is on initially (defaults to on)
+* Whether or not line highlighting is on initially (defaults to off)
+
+Please note that vim-gitgutter won't override any colours or highlights you've set in your colorscheme.
+
+
+#### Sign column
+
+The background colour of the sign column is controlled by the `SignColumn` highlight group.  This will be either set in your colour scheme or Vim's default.
+
+To find out where it's set, and to what it's set, use `:verbose highlight SignColumn`.
+
+If your `SignColumn` is not set (`:highlight SignColumn` gives you `SignColumn xxx cleared`), vim-gitgutter will set it to the same as your line number column (i.e. the `LineNr` highlight group).
+
+To change your sign column's appearance, update your colour scheme or `~/.vimrc` like this:
+
+* For the same appearance as your line number column: `highlight clear SignColumn`
+* For a specific appearance on terminal Vim: `highlight SignColumn ctermbg=whatever`
+* For a specific appearance on gVim/MacVim: `highlight SignColumn guibg=whatever`
+
+
+#### Signs' colours
+
+To customise these, put this in your colorscheme or `~/.vimrc`:
+
+
+
 ### FAQ
 
 > The colours in the sign column are weird.
 
-The syntax highlighting for your sign column is probably set strangely.  Either modify your colorscheme or add this to your `~/.vimrc`:
+Please see the section above on customising the sign column.
 
-```
-highlight clear SignColumn
-```
 
 > What happens if I also use another plugin which uses signs (e.g. Syntastic)?
 

plugin/gitgutter.vim

@@ -38,7 +38,6 @@ function! s:init()
   endif
 endfunction
 
-
 " }}}
 
 " Utility {{{
@@ -86,6 +85,10 @@ function! s:is_tracked_by_git()
   return !v:shell_error
 endfunction
 
+function! s:snake_case_to_camel_case(text)
+  return substitute(a:text, '\v(.)(\a+)(_(.)(.+))?', '\u\1\l\2\u\4\l\5', '')
+endfunction
+
 " }}}
 
 " {{{ Colours and signs
@@ -140,7 +143,6 @@ function! s:update_line_highlights(highlight_lines)
   redraw!
 endfunction
 
-
 " }}}
 
 " Diff processing {{{
@@ -305,8 +307,7 @@ endfunction
 function! s:show_signs(file_name, modified_lines)
   for line in a:modified_lines
     let line_number = line[0]
-    " snake case to camel case
-    let type = substitute(line[1], '\v(.)(\a+)(_(.)(.+))?', '\u\1\l\2\u\4\l\5', '')
+    let type = s:snake_case_to_camel_case(line[1])
     call s:add_sign(line_number, 'GitGutterLine' . type, a:file_name)
   endfor
 endfunction