Retool :Git blame colored commits

Use 3 characters of the commit hash rather than 6, limiting the maximum
total declarations to 4,096 rather than 16 million. Avoid color
components lower than 0x20 and higher than 0xdf to help avoid colors
that blend into the background, light or dark.  And for the terminal,
replace the use of CSApprox with a simple usage of the 6x6x6 color cube
found on 256 color terminals.  CSApprox aims to provide accurate
replication of the input colors, whereas our goal is simply to use all
colors in roughly equal amounts.

autoload/fugitive.vim

@@ -5725,7 +5725,6 @@ function! fugitive#BlameSyntax() abort
   syn spell notoplevel
   syn match FugitiveblameBlank                      "^\s\+\s\@=" nextgroup=FugitiveblameAnnotation,FugitiveblameScoreDebug,FugitiveblameOriginalFile,FugitiveblameOriginalLineNumber skipwhite
   syn match FugitiveblameHash       "\%(^\^\=[?*]*\)\@<=\<\x\{7,\}\>" nextgroup=FugitiveblameAnnotation,FugitiveblameScoreDebug,FugitiveblameOriginalLineNumber,FugitiveblameOriginalFile skipwhite
-  syn match FugitiveblameUncommitted "\%(^\^\=\)\@<=\<0\{7,\}\>" nextgroup=FugitiveblameAnnotation,FugitiveblameScoreDebug,FugitiveblameOriginalLineNumber,FugitiveblameOriginalFile skipwhite
   if s:HasOpt(flags, '-b') || FugitiveConfigGet('blame.blankBoundary') =~# '^1$\|^true$'
     syn match FugitiveblameBoundaryIgnore "^\^[*?]*\x\{7,\}\>" nextgroup=FugitiveblameAnnotation,FugitiveblameScoreDebug,FugitiveblameOriginalLineNumber,FugitiveblameOriginalFile skipwhite
   else
@@ -5757,31 +5756,37 @@ function! fugitive#BlameSyntax() abort
   endif
   let seen = {}
   for lnum in range(1, line('$'))
-    let hash = matchstr(getline(lnum), '^\^\=\zs\x\{6\}')
+    let orig_hash = matchstr(getline(lnum), '^\^\=[*?]*\zs\x\{6\}')
-    if hash ==# '' || hash ==# '000000' || has_key(seen, hash)
+    let hash = orig_hash
+    let hash = substitute(hash, '\(\x\)\x', '\=submatch(1).printf("%x", 15-str2nr(submatch(1),16))', 'g')
+    let hash = substitute(hash, '\(\x\x\)', '\=printf("%02x", str2nr(submatch(1),16)*3/4+32)', 'g')
+    if hash ==# '' || orig_hash ==# '000000' || has_key(seen, hash)
       continue
     endif
     let seen[hash] = 1
-    if &t_Co > 16 && get(g:, 'CSApprox_loaded') && !empty(findfile('autoload/csapprox/per_component.vim', escape(&rtp, ' ')))
+    if &t_Co == 256
-          \ && empty(get(s:hash_colors, hash))
+      let [s, r, g, b; __] = map(matchlist(orig_hash, '\(\x\)\x\(\x\)\x\(\x\)\x'), 'str2nr(v:val,16)')
-      let [s, r, g, b; __] = map(matchlist(hash, '\(\x\x\)\(\x\x\)\(\x\x\)'), 'str2nr(v:val,16)')
+      let color = 16 + (r + 1) / 3 * 36 + (g + 1) / 3 * 6 + (b + 1) / 3
-      let color = csapprox#per_component#Approximate(r, g, b)
+      if color == 16
-      if color == 16 && &background ==# 'dark'
+        let color = 235
-        let color = 8
+      elseif color == 231
+        let color = 255
       endif
       let s:hash_colors[hash] = ' ctermfg='.color
     else
       let s:hash_colors[hash] = ''
     endif
-    exe 'syn match FugitiveblameHash'.hash.'       "\%(^\^\=\)\@<='.hash.'\x\{1,34\}\>" nextgroup=FugitiveblameAnnotation,FugitiveblameOriginalLineNumber,fugitiveblameOriginalFile skipwhite'
+    let pattern = substitute(orig_hash, '^\(\x\)\x\(\x\)\x\(\x\)\x$', '\1\\x\2\\x\3\\x', '') . '*\>'
+    exe 'syn match FugitiveblameHash'.hash.'       "\%(^\^\=[*?]*\)\@<='.pattern.'" nextgroup=FugitiveblameAnnotation,FugitiveblameOriginalLineNumber,fugitiveblameOriginalFile skipwhite'
   endfor
+  syn match FugitiveblameUncommitted "\%(^\^\=[?*]*\)\@<=\<0\{7,\}\>" nextgroup=FugitiveblameAnnotation,FugitiveblameScoreDebug,FugitiveblameOriginalLineNumber,FugitiveblameOriginalFile skipwhite
   call s:BlameRehighlight()
 endfunction
 
 function! s:BlameRehighlight() abort
   for [hash, cterm] in items(s:hash_colors)
     if !empty(cterm) || has('gui_running') || has('termguicolors') && &termguicolors
-      exe 'hi FugitiveblameHash'.hash.' guifg=#'.hash.get(s:hash_colors, hash, '')
+      exe 'hi FugitiveblameHash'.hash.' guifg=#' . hash . cterm
     else
       exe 'hi link FugitiveblameHash'.hash.' Identifier'
     endif

doc/fugitive.txt

@@ -59,6 +59,12 @@ that are part of Git repositories).
                         ~     reblame at [count]th first grandparent
                         P     reblame at [count]th parent (like HEAD^[count])
 
+                                                *g:fugitive_dynamic_colors*
+                        In the GUI or a 256 color terminal, commit hashes will
+                        highlighted in different colors. To disable this:
+>
+                        let g:fugitive_dynamic_colors = 0
+<
 :[range]Git blame [...] If a range is given, just that part of the file will
 :Git blame [...] {file} be blamed, and a horizontal split without
                         scrollbinding is used.  You can also give an arbitrary