From 9e0913fa71697863f3e9ca155e3b1f67a69bdb7c Mon Sep 17 00:00:00 2001
From: Jacob Moody <moody@posixcafe.org>
Date: Fri, 3 Jan 2025 00:51:43 +0000
Subject: [PATCH] libmemdraw: change openmemsubfont() to accept rune minimum as
 argument

Subfonts for non ascii characters are offset by some minimum rune,
typically specified within the parent font file.  Because libmemdraw
only deals in subfonts, if we want to have it draw non ascii runes we
need some method of providing that base offset.

This function is only used in one place, so update the function
signature and fix the only caller.
---
 sys/include/memdraw.h               | 3 ++-
 sys/man/2/memdraw                   | 2 +-
 sys/src/cmd/venti/srv/graph.c       | 2 +-
 sys/src/libmemdraw/openmemsubfont.c | 3 ++-
 sys/src/libmemdraw/string.c         | 2 ++
 5 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/sys/include/memdraw.h b/sys/include/memdraw.h
index f1bb41e3f..62cc8cae5 100644
--- a/sys/include/memdraw.h
+++ b/sys/include/memdraw.h
@@ -80,6 +80,7 @@ struct	Memsubfont
 	short	n;		/* number of chars in font */
 	uchar	height;		/* height of bitmap */
 	char	ascent;		/* top of bitmap to baseline */
+	Rune	min;		/* rune offset for first glyph in subfont */
 	Fontchar *info;		/* n+1 character descriptors */
 	Memimage	*bits;		/* of font */
 };
@@ -156,7 +157,7 @@ extern int	memimageinit(void);
  * Subfont management
  */
 extern Memsubfont*	allocmemsubfont(char*, int, int, int, Fontchar*, Memimage*);
-extern Memsubfont*	openmemsubfont(char*);
+extern Memsubfont*	openmemsubfont(char*, Rune);
 extern void	freememsubfont(Memsubfont*);
 extern Point	memsubfontwidth(Memsubfont*, char*);
 extern Memsubfont*	getmemdefont(void);
diff --git a/sys/man/2/memdraw b/sys/man/2/memdraw
index 0500a561b..865dbdd09 100644
--- a/sys/man/2/memdraw
+++ b/sys/man/2/memdraw
@@ -150,7 +150,7 @@ int	memlineendsize(int end)
 .nf
 Memsubfont*	allocmemsubfont(char *name, int n, int height,
 	   int ascent, Fontchar *info, Memimage *i)
-Memsubfont*	openmemsubfont(char *name)
+Memsubfont*	openmemsubfont(char *name, Rune min)
 void	freememsubfont(Memsubfont *f)
 Point	memsubfontwidth(Memsubfont *f, char *s)
 Memsubfont*	getmemdefont(void)
diff --git a/sys/src/cmd/venti/srv/graph.c b/sys/src/cmd/venti/srv/graph.c
index cbad1ada2..780c674da 100644
--- a/sys/src/cmd/venti/srv/graph.c
+++ b/sys/src/cmd/venti/srv/graph.c
@@ -58,7 +58,7 @@ ginit(void)
 #ifdef PLAN9PORT
 	smallfont = openmemsubfont(unsharp("#9/font/lucsans/lstr.10"));
 #else
-	smallfont = openmemsubfont("/lib/font/bit/lucidasans/lstr.10");
+	smallfont = openmemsubfont("/lib/font/bit/lucidasans/lstr.10", 0);
 #endif
 	black = memblack;
 	blue = allocrepl(DBlue);
diff --git a/sys/src/libmemdraw/openmemsubfont.c b/sys/src/libmemdraw/openmemsubfont.c
index 1a17cfde6..22a644c29 100644
--- a/sys/src/libmemdraw/openmemsubfont.c
+++ b/sys/src/libmemdraw/openmemsubfont.c
@@ -4,7 +4,7 @@
 #include <memdraw.h>
 
 Memsubfont*
-openmemsubfont(char *name)
+openmemsubfont(char *name, Rune min)
 {
 	Memsubfont *sf;
 	Memimage *i;
@@ -45,6 +45,7 @@ openmemsubfont(char *name)
 		free(fc);
 		goto Err;
 	}
+	sf->min = min;
 	close(fd);
 	free(p);
 	return sf;
diff --git a/sys/src/libmemdraw/string.c b/sys/src/libmemdraw/string.c
index c0a6dc2de..69b4b5ab5 100644
--- a/sys/src/libmemdraw/string.c
+++ b/sys/src/libmemdraw/string.c
@@ -25,6 +25,7 @@ memimagestring(Memimage *b, Point p, Memimage *color, Point cp, Memsubfont *f, c
 			}
 			s += w;
 		}
+		c -= f->min;
 		if(c >= f->n)
 			continue;
 		i = f->info+c;
@@ -58,6 +59,7 @@ memsubfontwidth(Memsubfont *f, char *cs)
 			}
 			s += w;
 		}
+		c -= f->min;
 		if(c >= f->n)
 			continue;
 		i = f->info+c;