function theme_precmd {

     local TERMWIDTH
     (( TERMWIDTH = ${COLUMNS} - 1 ))
 
 
     ###
     # Truncate the path if it's too long.

     PR_FILLBAR=""
     PR_PWDLEN=""

     local promptsize=${#${(%):---(%n@%m:%l)---()--}}

     local rubyprompt=`rvm_prompt_info || rbenv_prompt_info`

     local rubypromptsize=${#${rubyprompt}}
     local pwdsize=${#${(%):-%~}}

     if [[ "$promptsize + $rubypromptsize + $pwdsize" -gt $TERMWIDTH ]]; then
       ((PR_PWDLEN=$TERMWIDTH - $promptsize))
     else
       PR_FILLBAR="\${(l.(($TERMWIDTH - ($promptsize + $rubypromptsize + $pwdsize)))..${PR_HBAR}.)}"
     fi
 
 }
 
 
 setopt extended_glob

 theme_preexec () {

     if [[ "$TERM" == "screen" ]]; then
 	local CMD=${1[(wr)^(*=*|sudo|-*)]}
 	echo -n "\ek$CMD\e\\"
     fi
 }
 
 
 setprompt () {
     ###
     # Need this so the prompt will work.
 
     setopt prompt_subst
 
 
     ###
     # See if we can use colors.
 
     autoload colors zsh/terminfo
     if [[ "$terminfo[colors]" -ge 8 ]]; then
 	colors
     fi
     for color in RED GREEN YELLOW BLUE MAGENTA CYAN WHITE GREY; do
 	eval PR_$color='%{$terminfo[bold]$fg[${(L)color}]%}'
 	eval PR_LIGHT_$color='%{$fg[${(L)color}]%}'
 	(( count = $count + 1 ))
     done
     PR_NO_COLOUR="%{$terminfo[sgr0]%}"
 
     ###
     # Modify Git prompt
     ZSH_THEME_GIT_PROMPT_PREFIX=" on %{$fg[green]%}"
     ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%}"
     ZSH_THEME_GIT_PROMPT_DIRTY=""
     ZSH_THEME_GIT_PROMPT_CLEAN=""
 
     ZSH_THEME_GIT_PROMPT_ADDED="%{$fg[green]%} ✚"
     ZSH_THEME_GIT_PROMPT_MODIFIED="%{$fg[blue]%} ✹"
     ZSH_THEME_GIT_PROMPT_DELETED="%{$fg[red]%} ✖"
     ZSH_THEME_GIT_PROMPT_RENAMED="%{$fg[magenta]%} ➜"
     ZSH_THEME_GIT_PROMPT_UNMERGED="%{$fg[yellow]%} ═"
     ZSH_THEME_GIT_PROMPT_UNTRACKED="%{$fg[cyan]%} ✭"
 
     ###
     # See if we can use extended characters to look nicer.

     typeset -A altchar
     set -A altchar ${(s..)terminfo[acsc]}
     PR_SET_CHARSET="%{$terminfo[enacs]%}"
     PR_SHIFT_IN="%{$terminfo[smacs]%}"
     PR_SHIFT_OUT="%{$terminfo[rmacs]%}"
     PR_HBAR=${altchar[q]:--}
     PR_ULCORNER=${altchar[l]:--}
     PR_LLCORNER=${altchar[m]:--}
     PR_LRCORNER=${altchar[j]:--}
     PR_URCORNER=${altchar[k]:--}
 

     ###
     # Decide if we need to set titlebar text.

     case $TERM in
 	xterm*)
 	    PR_TITLEBAR=$'%{\e]0;%(!.-=*[ROOT]*=- | .)%n@%m:%~ | ${COLUMNS}x${LINES} | %y\a%}'
 	    ;;
 	screen)
 	    PR_TITLEBAR=$'%{\e_screen \005 (\005t) | %(!.-=[ROOT]=- | .)%n@%m:%~ | ${COLUMNS}x${LINES} | %y\e\\%}'
 	    ;;
 	*)
 	    PR_TITLEBAR=''
 	    ;;
     esac

     ###
     # Decide whether to set a screen title
     if [[ "$TERM" == "screen" ]]; then
 	PR_STITLE=$'%{\ekzsh\e\\%}'
     else
 	PR_STITLE=''
     fi

     ###
     # Finally, the prompt.
 
     PROMPT='$PR_SET_CHARSET$PR_STITLE${(e)PR_TITLEBAR}\
 $PR_CYAN$PR_SHIFT_IN$PR_ULCORNER$PR_HBAR$PR_SHIFT_OUT$PR_GREY(\
 $PR_GREEN%$PR_PWDLEN<...<%~%<<\

 $PR_GREY)`rvm_prompt_info || rbenv_prompt_info`$PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_HBAR${(e)PR_FILLBAR}$PR_HBAR$PR_SHIFT_OUT$PR_GREY(\

 $PR_CYAN%(!.%SROOT%s.%n)$PR_GREY@$PR_GREEN%m:%l\
 $PR_GREY)$PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_URCORNER$PR_SHIFT_OUT\
 
 $PR_CYAN$PR_SHIFT_IN$PR_LLCORNER$PR_BLUE$PR_HBAR$PR_SHIFT_OUT(\
 $PR_YELLOW%D{%H:%M:%S}\
 $PR_LIGHT_BLUE%{$reset_color%}`git_prompt_info``git_prompt_status`$PR_BLUE)$PR_CYAN$PR_SHIFT_IN$PR_HBAR\
 $PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT\
 >$PR_NO_COLOUR '
 
     # display exitcode on the right when >0
     return_code="%(?..%{$fg[red]%}%? ↵ %{$reset_color%})"
     RPROMPT=' $return_code$PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_BLUE$PR_HBAR$PR_SHIFT_OUT\
 ($PR_YELLOW%D{%a,%b%d}$PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_CYAN$PR_LRCORNER$PR_SHIFT_OUT$PR_NO_COLOUR'
 
     PS2='$PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT\
 $PR_BLUE$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT(\
 $PR_LIGHT_GREEN%_$PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT\
 $PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT$PR_NO_COLOUR '
 }
 
 setprompt

 
 autoload -U add-zsh-hook
 add-zsh-hook precmd  theme_precmd
 add-zsh-hook preexec theme_preexec