From c3645c967a7998cb73d81b8065bc305c906e83f2 Mon Sep 17 00:00:00 2001
From: Nick White <git@njw.me.uk>
Date: Mon, 21 Oct 2013 18:09:59 +0100
Subject: Add some markdown processing

---
 tkread | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/tkread b/tkread
index 8c5d318..e607bf8 100755
--- a/tkread
+++ b/tkread
@@ -2,6 +2,9 @@
 # Usage: tkread [-w]
 #        -w rewrap lines
 #
+# The markdown parsing is inspired by the code of smu:
+# <https://github.com/Gottox/smu> 
+#
 # TODO:
 # - justify text (not simple; see http://wiki.tcl.tk/1774)
 # - add a basic search function
@@ -13,6 +16,13 @@ set fontsize 20
 set colour #333333
 set inverted 0
 set drag 0
+set tagnum 0
+
+set surroundfmt { \
+      {"***" "bold italic"} \
+      {"**" "bold"} \
+      {"*" "italic"} \
+     }
 
 package require Tk
 
@@ -24,12 +34,65 @@ proc rewrap {text} {
 	return [regsub -all {\n\n\n} $better "\n"]
 }
 
+# This uses marks before tags, as they handle deletions fine, so
+# marks can be made and then the formatting characters can be
+# deleted without affecting the position for formatting.
+proc markup {widget} {
+	global surroundfmt
+	global fontsize
+	global tagnum
+
+	foreach fmt $surroundfmt {
+		set searchchar [lindex $fmt 0]
+		set fmtstring [lindex $fmt 1]
+		set searchlen [string length $searchchar]
+		set insection 0
+		set cur ""
+		set markonnum 0
+		set markoffnum 0
+
+		set cur [$widget search $searchchar 0.0 end]
+		while {$cur != ""} {
+			if {$insection == 0} {
+				set insection 1
+				$widget mark set markon_$markonnum $cur
+				incr markonnum
+			} else {
+				set insection 0
+				$widget mark set markoff_$markoffnum $cur
+				incr markoffnum
+			}
+			$widget delete $cur "$cur + $searchlen chars"
+
+			set cur [$widget search "$searchchar" $cur end]
+		}
+
+		# ignore any final mismatched mark
+		if {$markonnum != $markoffnum } {
+			set markonnum $markoffnum
+		}
+
+		for {set x 0} {$x < $markonnum} {incr x} {
+			$widget tag add tag_$tagnum markon_$x markoff_$x
+		}
+
+		$widget tag configure tag_$tagnum -font "Times $fontsize $fmtstring"
+		incr tagnum
+	}
+}
+
 proc changeFontSize {change} {
 	global fontsize
+	global surroundfmt
+	global tagnum
 	set newsize [expr $fontsize $change]
 	if {$newsize > 0} {
 		set fontsize $newsize
 		.t configure -font "Times $fontsize" -padx [expr $fontsize * 3] -spacing2 [expr [font metrics "Times $fontsize" -linespace] / 4]
+		for {set x 0} {$x < $tagnum} {incr x} {
+			set fmtstring [lindex [lindex $surroundfmt $x] 1]
+			.t tag configure tag_$x -font "Times $fontsize $fmtstring"
+		}
 	}
 }
 
@@ -69,6 +132,7 @@ if { $::argc > 0 && [lindex $::argv 0] == "-w" } {
 	set text [rewrap $text]
 }
 .t insert end $text
+markup .t
 .t configure -state disabled ;# disable cursor
 
 bind . <Up> {scroll -1 unit}
-- 
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