From 281765923e6247890649058c366e67e6ea7e4cce Mon Sep 17 00:00:00 2001
From: sls <sls>
Date: Mon, 5 Jun 1995 02:42:26 +0000
Subject: [PATCH] Implement forward, back, and go.

---
 help.tcl | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/help.tcl b/help.tcl
index a7267f2..eb2e449 100644
--- a/help.tcl
+++ b/help.tcl
@@ -2,19 +2,30 @@
 # $Id$
 #
 
-lappend auto_path /usr/local/lib/stl
-
 dialog help_window {
     param topics {}
     param width 50
     param height 35
     param helpdir .
+    member history {}
+    member history_ndx -1
+    member history_len 0
     method create {} {
 	frame $self.menu -relief raised -bd 2
 	menubutton $self.menu.topics -text "Topics" -underline 0 \
 	    -menu $self.menu.topics.m
 	pack $self.menu.topics -in $self.menu -side left
 	set m [menu $self.menu.topics.m]
+	menubutton $self.menu.navigate -text "Navigate" -underline 0 \
+	    -menu $self.menu.navigate.m
+	pack $self.menu.navigate -in $self.menu -side left
+	set m [menu $self.menu.navigate.m]
+	$m add command -label "Forward" -underline 0 -state disabled \
+	    -command "$self forward"
+	$m add command -label "Back" -underline 0 -state disabled \
+	    -command "$self back"
+	$m add cascade -label "Go" -underline 0 -menu $m.go
+	menu $m.go -postcommand "$self fill_go_menu"
 	frame $self.text -bd 2 -relief raised
 	scrollbar $self.text.sb -command "$self.text.t yview"
 	text $self.text.t -relief sunken -bd 2 -yscroll "$self.text.sb set" \
@@ -40,15 +51,20 @@ dialog help_window {
 	$self.text.t config -width $slot(width) -height $slot(height)
     }
     method show_topic {topic} {
-	set slot(topic) $topic
+	incr slot(history_ndx)
+	set slot(history) [lrange $slot(history) 0 $slot(history_ndx)]
+	set slot(history_len) [expr $slot(history_ndx) + 1]
+	lappend slot(history) $topic
 	$self read_topic $topic
-	wm title $self "Help: $topic"
     }
     method read_topic {topic} {
+	set slot(topic) $topic
+	wm title $self "Help: $topic"
 	set f [open $slot(helpdir)/$topic.html r]
 	set txt [read $f]
 	close $f
-	feedback .help_feedback -steps [set slot(len) [string length $txt]]
+	feedback .help_feedback -steps [set slot(len) [string length $txt]] \
+	    -title "Rendering HTML"
 	set slot(remaining) $slot(len)
 	grab set .help_feedback
 	tkhtml_set_render_hook "$self update_feedback"
@@ -56,9 +72,37 @@ dialog help_window {
 	tkhtml_render $self.text.t $txt
 	grab release .help_feedback
 	destroy .help_feedback
+	set m $self.menu.navigate.m
+	if {($slot(history_ndx)+1) < $slot(history_len)} {
+	    $m entryconfig 1 -state normal
+	} else {
+	    $m entryconfig 1 -state disabled
+	}
+	if {$slot(history_ndx) > 0} {
+	    $m entryconfig 2 -state normal
+	} else {
+	    $m entryconfig 2 -state disabled
+	}
     }
     method follow_link {link} {
-	$self read_topic [file root $link]
+	$self show_topic [file root $link]
+    }
+    method forward {} {
+	incr slot(history_ndx)
+	$self read_topic [lindex $slot(history) $slot(history_ndx)]
+    }
+    method back {} {
+	incr slot(history_ndx) -1
+	$self read_topic [lindex $slot(history) $slot(history_ndx)]
+    }
+    method fill_go_menu {} {
+	set m $self.menu.navigate.m.go
+	catch {$m delete 0 last}
+	for {set i [expr [llength $slot(history)]-1]} {$i >= 0} {incr i -1} {
+	    set topic [lindex $slot(history) $i]
+	    $m add command -label $topic \
+		-command [list $self show_topic $topic]
+	}
     }
     method update_feedback {n} {
 	if {($slot(remaining) - $n) > .1*$slot(len)} {
-- 
2.23.0