Initial revision
diff --git a/src/libdraw/stringwidth.c b/src/libdraw/stringwidth.c
new file mode 100644
index 0000000..c487791
--- /dev/null
+++ b/src/libdraw/stringwidth.c
@@ -0,0 +1,97 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+
+static Rune empty[] = { 0 };
+int
+_stringnwidth(Font *f, char *s, Rune *r, int len)
+{
+ int wid, twid, n, max, l;
+ char *name;
+ enum { Max = 64 };
+ ushort cbuf[Max];
+ Rune rune, **rptr;
+ char *subfontname, **sptr;
+ Font *def;
+
+ if(s == nil){
+ s = "";
+ sptr = nil;
+ }else
+ sptr = &s;
+ if(r == nil){
+ r = empty;
+ rptr = nil;
+ }else
+ rptr = &r;
+ twid = 0;
+ while((*s || *r) && len){
+ max = Max;
+ if(len < max)
+ max = len;
+ n = 0;
+ while((l = cachechars(f, sptr, rptr, cbuf, max, &wid, &subfontname)) <= 0){
+ if(++n > 10){
+ if(*r)
+ rune = *r;
+ else
+ chartorune(&rune, s);
+ if(f->name != nil)
+ name = f->name;
+ else
+ name = "unnamed font";
+ fprint(2, "stringwidth: bad character set for rune 0x%.4ux in %s\n", rune, name);
+ return twid;
+ }
+ if(subfontname){
+ if(_getsubfont(f->display, subfontname) == 0){
+ def = f->display->defaultfont;
+ if(def && f!=def)
+ f = def;
+ else
+ break;
+ }
+ }
+ }
+ agefont(f);
+ twid += wid;
+ len -= l;
+ }
+ return twid;
+}
+
+int
+stringnwidth(Font *f, char *s, int len)
+{
+ return _stringnwidth(f, s, nil, len);
+}
+
+int
+stringwidth(Font *f, char *s)
+{
+ return _stringnwidth(f, s, nil, 1<<24);
+}
+
+Point
+stringsize(Font *f, char *s)
+{
+ return Pt(_stringnwidth(f, s, nil, 1<<24), f->height);
+}
+
+int
+runestringnwidth(Font *f, Rune *r, int len)
+{
+ return _stringnwidth(f, nil, r, len);
+}
+
+int
+runestringwidth(Font *f, Rune *r)
+{
+ return _stringnwidth(f, nil, r, 1<<24);
+}
+
+Point
+runestringsize(Font *f, Rune *r)
+{
+ return Pt(_stringnwidth(f, nil, r, 1<<24), f->height);
+}
