guarddescent for EAN/UPC; guards now descend so height is for nominal bars

Author: terryburton

CHANGES

@@ -1,3 +1,9 @@
+2026-04-09
+
+* A guarddescent option was added to specify the descent of EAN/UPC guard bars in multiples of the X-dimension.
+* EAN/UPC guards now correctly descend below the baseline so that height relates to the nominal bars.
+
+
 2026-04-08
 
 * Under propspec, the height option now acts as a multiplier on the spec-derived bar height.

src/ean13.ps.src

@@ -71,8 +71,9 @@ begin
     /text1font /Helvetica def
     /text1size 12.0 def
     /text1xoffset -7.75 def
-    /text1yoffset -.25 def
+    /text1yoffset -5.25 def
     /height -1.0 def
+    /guarddescent 5 def
     /width 0 def
     /addongap 12.0 def
     /addontextfont (unset) def
@@ -134,6 +135,8 @@ begin
     /ean13 ast /apply_ast //render exec not { //raiseerror exec } if
     /resolve_strictspec //render exec
 
+    /descent guarddescent modunit mul 72 div def  % Guard bar descent
+
     %
     % Add checksum digit
     %
@@ -227,15 +230,15 @@ begin
     /height /resolve_height //render exec dup -1 eq { pop 1.0 } if def
 
     includetext {
-        /descent 5 modunit mul 72 div def  % Guard bar descent: 5X
-        /bhs [height height 12{height descent sub}repeat height height 12{height descent sub}repeat height height] def
-        /bbs [0 0 12{descent}repeat 0 0 12{descent}repeat 0 0] def
+        /guardheight height descent add def
+        /bhs [guardheight guardheight 12{height}repeat guardheight guardheight 12{height}repeat guardheight guardheight] def
+        /bbs [descent neg descent neg 12{0}repeat descent neg descent neg 12{0}repeat descent neg descent neg] def
     } {
         /bhs [30{height}repeat] def
         /bbs [30{0}repeat] def
         /txt [] def
     } ifelse
-    /guardrightypos 0.0 def
+    /guardrightypos -5.0 def
 
     %
     % Append the addon
@@ -244,6 +247,7 @@ begin
         /addopts <<
             /includetext true
             /height height includetext { 0.15 sub } if
+            /guarddescent guarddescent
             /text1xoffset addontextxoffset null ne {addontextxoffset} {98.25 addongap add} ifelse
             addontextyoffset null ne {/text1yoffset addontextyoffset} if
             /text1size addontextsize null ne {addontextsize} {text1size} ifelse
@@ -273,7 +277,7 @@ begin
     /borderleft 11.0
     /borderright addon () eq {7.0} {5.0} ifelse
     /bordertop 0.0
-    /borderbottom 5.0
+    /borderbottom 5.0 guarddescent modunit mul add
     /strictspec strictspec
     /loosespec loosespec
     /xdim xdim

src/ean13composite.ps.src

@@ -187,6 +187,8 @@ begin
 
     % Main symbol bars extend to full height connecting to separator; add-on bars keep their height
     /linheight 0 bhsrow { ceiling cvi 2 copy lt { exch } if pop } forall def
+    /lindescent 0 bbsrow { floor cvi 2 copy gt { exch } if pop } forall def
+    txt { dup 2 get lindescent neg add 2 exch put } forall
     /mainbars nbars def
     0 1 sbs length 1 sub {
         dup sbs exch get type /realtype eq { 1 add 2 idiv /mainbars exch def exit } { pop } ifelse
@@ -197,7 +199,7 @@ begin
     /rowbuf pixx string def
     /prevrow () def  /linrowmult 72 array def  /lri 0 def
     /linpixs [
-        linheight 1 sub -1 0 {
+        linheight 1 sub -1 lindescent {
             /y exch def
             /p 0 def
             linpad { rowbuf p 3 -1 roll put /p p 1 add def } forall
@@ -246,13 +248,13 @@ begin
         2 copy lt { exch } if pop dup 0 lt { pop 0 } if
     def
     /bordertop 1 def
-    /borderbottom linsym /borderbottom 2 copy known { get } { pop pop 0 } ifelse def
+    /borderbottom linsym /borderbottom 2 copy known { get } { pop pop 0 } ifelse lindescent add def
 
     % Guard positions adjusted for linear offset within matrix
     /guardleftpos linsym /guardleftpos 2 copy known { get linpad length 1 add sub } { pop pop 0 } ifelse def
-    /guardleftypos linsym /guardleftypos 2 copy known { get } { pop pop 0 } ifelse def
+    /guardleftypos linsym /guardleftypos 2 copy known { get lindescent neg add } { pop pop 0 } ifelse def
     /guardrightpos linsym /guardrightpos 2 copy known { get linpad length 1 add linwidth add pixx sub add } { pop pop 0 } ifelse def
-    /guardrightypos linsym /guardrightypos 2 copy known { get } { pop pop 0 } ifelse def
+    /guardrightypos linsym /guardrightypos 2 copy known { get lindescent neg add } { pop pop 0 } ifelse def
 
     % Height is already applied to the linear bars via bhs; don't let renmatrix rescale
     options /height undef

src/ean2.ps.src

@@ -69,6 +69,7 @@ begin
     /text1xoffset 3.25 def
     /text1yoffset null def  % sentinel realtype
     /height -1.0 def
+    /guarddescent 5 def
     /width 0 def
 
     /propspec false def
@@ -112,6 +113,8 @@ begin
 
     /height /resolve_height //render exec dup -1 eq { pop 0.7 } if def
 
+    /descent guarddescent modunit mul 72 div def  % Guard bar descent
+
     text1yoffset null eq {
         /text1yoffset height 72 mul 5.75 add def
     } if
@@ -158,8 +161,8 @@ begin
     <<
     /ren /renlinear
     /sbs [sbs {48 sub} forall]
-    /bhs [12{height}repeat]
-    /bbs [12{0}repeat]
+    /bhs [12{height descent add}repeat]
+    /bbs [12{descent neg}repeat]
     includetext {
         /txt txt
     } if

src/ean5.ps.src

@@ -72,6 +72,7 @@ begin
     /text1xoffset 3.25 def
     /text1yoffset null def  % realtype sentinel
     /height -1.0 def
+    /guarddescent 5 def
     /width 0 def
 
     /propspec false def
@@ -115,6 +116,8 @@ begin
 
     /height /resolve_height //render exec dup -1 eq { pop 0.7 } if def
 
+    /descent guarddescent modunit mul 72 div def  % Guard bar descent
+
     text1yoffset null eq {
         /text1yoffset height 72 mul 5.75 add def
     } if
@@ -172,8 +175,8 @@ begin
     <<
     /ren /renlinear
     /sbs [sbs {48 sub} forall]
-    /bhs [16 {height} repeat]
-    /bbs [16 {0} repeat]
+    /bhs [16 {height descent add} repeat]
+    /bbs [16 {descent neg} repeat]
     includetext {
         /txt txt
     } if

src/ean8.ps.src

@@ -68,8 +68,9 @@ begin
     /text1font /Helvetica def
     /text1size 12.0 def
     /text1xoffset 7.25 def
-    /text1yoffset -0.25 def
+    /text1yoffset -5.25 def
     /height -1.0 def
+    /guarddescent 5 def
     /width 0 def
 
     /propspec false def
@@ -136,6 +137,8 @@ begin
     /ean8 ast /apply_ast //render exec not { //raiseerror exec } if
     /resolve_strictspec //render exec
 
+    /descent guarddescent modunit mul 72 div def  % Guard bar descent
+
     %
     % Add checksum digit
     %
@@ -211,15 +214,15 @@ begin
     /height /resolve_height //render exec dup -1 eq { pop 1.0 } if def
 
     includetext {
-        /descent 5 modunit mul 72 div def  % Guard bar descent: 5X
-        /bhs [height height 8{height descent sub}repeat height height 8{height descent sub}repeat height height] def
-        /bbs [0 0 8{descent}repeat 0 0 8{descent}repeat 0 0] def
+        /guardheight height descent add def
+        /bhs [guardheight guardheight 8{height}repeat guardheight guardheight 8{height}repeat guardheight guardheight] def
+        /bbs [descent neg descent neg 8{0}repeat descent neg descent neg 8{0}repeat descent neg descent neg] def
     } {
         /bhs [22{height}repeat] def
         /bbs [22{0}repeat] def
         /txt [] def
     } ifelse
-    /guardrightypos 0.0 def
+    /guardrightypos -5.0 def
 
     %
     % Append the addon
@@ -228,6 +231,7 @@ begin
         /addopts <<
             /includetext true
             /height height includetext { 0.15 sub } if
+            /guarddescent guarddescent
             /text1xoffset addontextxoffset null ne {addontextxoffset} {70.25 addongap add} ifelse
             addontextyoffset null ne {/text1yoffset addontextyoffset} if
             /text1size addontextsize null ne {addontextsize} {text1size} ifelse
@@ -253,12 +257,13 @@ begin
     /txt txt
     /opt options
     /guardleftpos 7.0
+    /guardleftypos -5.0
     /guardrightpos addon () eq {7.0} {5.0} ifelse
     /guardrightypos guardrightypos
     /borderleft 7.0
     /borderright addon () eq {7.0} {5.0} ifelse
     /bordertop 0.0
-    /borderbottom 5.0
+    /borderbottom 5.0 guarddescent modunit mul add
     /strictspec strictspec
     /loosespec loosespec
     /xdim xdim

src/ean8composite.ps.src

@@ -183,6 +183,8 @@ begin
 
     % Main symbol bars extend to full height connecting to separator; add-on bars keep their height
     /linheight 0 bhsrow { ceiling cvi 2 copy lt { exch } if pop } forall def
+    /lindescent 0 bbsrow { floor cvi 2 copy gt { exch } if pop } forall def
+    txt { dup 2 get lindescent neg add 2 exch put } forall
     /mainbars nbars def
     0 1 sbs length 1 sub {
         dup sbs exch get type /realtype eq { 1 add 2 idiv /mainbars exch def exit } { pop } ifelse
@@ -193,7 +195,7 @@ begin
     /rowbuf pixx string def
     /prevrow () def  /linrowmult 72 array def  /lri 0 def
     /linpixs [
-        linheight 1 sub -1 0 {
+        linheight 1 sub -1 lindescent {
             /y exch def
             /p 0 def
             linpad { rowbuf p 3 -1 roll put /p p 1 add def } forall
@@ -242,13 +244,13 @@ begin
         2 copy lt { exch } if pop dup 0 lt { pop 0 } if
     def
     /bordertop 1 def
-    /borderbottom linsym /borderbottom 2 copy known { get } { pop pop 0 } ifelse def
+    /borderbottom linsym /borderbottom 2 copy known { get } { pop pop 0 } ifelse lindescent add def
 
     % Guard positions adjusted for linear offset within matrix
     /guardleftpos linsym /guardleftpos 2 copy known { get linpad length 1 add sub } { pop pop 0 } ifelse def
-    /guardleftypos linsym /guardleftypos 2 copy known { get } { pop pop 0 } ifelse def
+    /guardleftypos linsym /guardleftypos 2 copy known { get lindescent neg add } { pop pop 0 } ifelse def
     /guardrightpos linsym /guardrightpos 2 copy known { get linpad length 1 add linwidth add pixx sub add } { pop pop 0 } ifelse def
-    /guardrightypos linsym /guardrightypos 2 copy known { get } { pop pop 0 } ifelse def
+    /guardrightypos linsym /guardrightypos 2 copy known { get lindescent neg add } { pop pop 0 } ifelse def
 
     % Height is already applied to the linear bars via bhs; don't let renmatrix rescale
     options /height undef

src/isbn.ps.src

@@ -310,7 +310,7 @@ begin
             /isbntextxoffset isbn length 9 eq {-1.0} {-12.0} ifelse def
         } if
         isbntextyoffset null eq {
-            /isbntextyoffset args (bhs) get 0 get 72 mul 3 add def
+            /isbntextyoffset args (bhs) get 2 get 72 mul 3 add def
         } if
         args (txt) known {
             /txt args (txt) get def

src/ismn.ps.src

@@ -289,7 +289,7 @@ begin
             /ismntextxoffset ismntxt length 18 eq {-1.0} {-12.0} ifelse def
         } if
         ismntextyoffset null eq {
-            /ismntextyoffset args (bhs) get 0 get 72 mul 3 add def
+            /ismntextyoffset args (bhs) get 2 get 72 mul 3 add def
         } if
         args (txt) known {
             /txt args (txt) get def

src/issn.ps.src

@@ -233,7 +233,7 @@ begin
     %
     includetext {
         issntextxoffset null eq {/issntextxoffset 10.0 def} if
-        issntextyoffset null eq {/issntextyoffset args (bhs) get 0 get 72 mul 3 add def} if
+        issntextyoffset null eq {/issntextyoffset args (bhs) get 2 get 72 mul 3 add def} if
         args (txt) known {
             /txt args (txt) get def
             /newtxt txt length 1 add array def