@ .t tag config ln -foreground gray
@ .t tag config chng -background {#d0d0ff}
@ .t tag config add -background {#c0ffc0}
@ .t tag config rm -background {#ffc0c0}
@ proc dehtml {x} {
@   return [string map {&amp; & &lt; < &gt; > &#39; ' &quot; \"} $x]
@ }
@ # puts $cmd
@ set in [open $cmd r]
@ while {![eof $in]} {
@   set line [gets $in]
@   if {[regexp {^<a name="chunk.*"></a>} $line]} continue
@   if {[regexp {^===} $line]} {
@     set n [string length $line]
@     if {$n>$mx} {set mx $n}

** to the diff command.
** 
** Steps:
** (1) Write the Tcl/Tk script used for rendering into a temp file.
** (2) Invoke "wish" on the temp file using fossil_system().
** (3) Delete the temp file.
*/
static void diff_tk(void){
void diff_tk(const char *zSubCmd, int firstArg){
  int i;
  Blob script;
  char *zTempFile;
  char *zCmd;
  blob_zero(&script);
  blob_appendf(&script, "set cmd {| \"%/\" diff --html -y -i", g.nameOfExe);
  for(i=2; i<g.argc; i++){
    blob_appendf(&script, " \"%s\"", g.argv[i]);
  blob_appendf(&script, "set cmd {| \"%/\" %s --html -y -i",
               g.nameOfExe, zSubCmd);
  for(i=firstArg; i<g.argc; i++){
    blob_append(&script, " ", 1);
    shell_escape(&script, g.argv[i]);
  }
  blob_appendf(&script, "}\n%s", zDiffScript);
  zTempFile = write_blob_to_temp_file(&script);
  zCmd = mprintf("tclsh \"%s\"", zTempFile);
  fossil_system(zCmd);
  file_delete(zTempFile);
  fossil_free(zCmd);
}

/*
** Returns non-zero if files that may be binary should be used with external
** diff programs.
*/
int diff_include_binary_files(void){

  const char *zDiffCmd = 0;  /* External diff command. NULL for internal diff */
  const char *zBinGlob = 0;  /* Treat file names matching this as binary */
  int fIncludeBinary = 0;    /* Include binary files for external diff */
  u64 diffFlags = 0;         /* Flags to control the DIFF */
  int f;

  if( find_option("tk",0,0)!=0 ){
    diff_tk();
    diff_tk("diff", 2);
    return;
  }
  isGDiff = g.argv[1][0]=='g';
  isInternDiff = find_option("internal","i",0)!=0;
  zFrom = find_option("from", "r", 1);
  zTo = find_option("to", 0, 1);
  zBranch = find_option("branch", 0, 1);