Merge branch 'vim/guess-background'

3 files changed, 30 insertions, 7 deletions

diff --git a/tmux/tmux.conf b/tmux/tmux.conf
index 4e277515..2eb1665a 100644
--- a/tmux/tmux.conf
+++ b/tmux/tmux.conf
@@ -1,7 +1,5 @@
 # Strip out a lot of machine and X11 dependent crap from the initial
 # environment
-set-environment -gru COLORFGBG
-set-environment -gru COLORTERM
 set-environment -gru DISPLAY
 set-environment -gru SSH_CLIENT
 set-environment -gru SSH_CONNECTION
@@ -10,7 +8,7 @@ set-environment -gru WINDOWID
 
 # Otherwise, use the environment we had when we started; don't touch it during
 # a session unless I specifically ask
-set-option -g update-environment ''
+set-option -g update-environment 'COLORFGBG COLORTERM'
 
 # Setting this makes each new pane a non-login shell, which suits me better
 set-option -g default-command "$SHELL"
diff --git a/vim/config/syntax.vim b/vim/config/syntax.vim
index af332ba3..250ce924 100644
--- a/vim/config/syntax.vim
+++ b/vim/config/syntax.vim
@@ -5,8 +5,31 @@ if has('syntax')
   silent! syntax enable
   silent! syntax sync minlines=100
 
-  " I almost always use a dark background, so use that version of the selected
-  " colorscheme
-  set background=dark
+  " Invert Vim's built-in logic for choosing dark or light backgrounds; we'll
+  " default to choosing a dark background unless we find some reason *not* to.
+  if has('eval')
+
+    " Wrap all this logic in a function
+    function! DetectBackground()
+
+      " Split up the value of $COLORFGBG (if any) by semicolons
+      let l:colorfgbg = split($COLORFGBG, ';')
+
+      " Get the background color value, or an empty string if none
+      let l:bg = len(l:colorfgbg) ? l:colorfgbg[-1] : ''
+
+      " Choose the background setting based on this value
+      if l:bg == 'default' || l:bg == '7' || l:bg == '15'
+          set background=light
+      else
+          set background=dark
+      endif
+
+    endfunction
+
+    " Cull the function just defined directly
+    call DetectBackground()
+
+  endif
 
 endif
diff --git a/vim/vimrc b/vim/vimrc
index d225a148..043dea8b 100644
--- a/vim/vimrc
+++ b/vim/vimrc
@@ -24,8 +24,10 @@ if v:version >= 701
   silent! call pathogen#infect()
   silent! call pathogen#helptags()
 
-  " With the plugins loaded, we might now be able to use my custom colorscheme
+  " The 'sahara' colorscheme only works for dark backgrounds with 256 colors
   if has('syntax')
+        \ && &background == 'dark'
+        \ && (has('gui_running') || &t_Co == 256)
     silent! colorscheme sahara
   endif
 endif