1 files changed, 50 insertions, 0 deletions
diff --git a/pith/charconv/utf8.c b/pith/charconv/utf8.c
index 411e1ddd..bca0d26b 100644
--- a/pith/charconv/utf8.c
+++ b/pith/charconv/utf8.c
@@ -1049,6 +1049,56 @@ utf8_width(char *str)
 
 
 /*
+ * Returns the screen cells width of the UTF-8 string argument, treating tabs
+ * in a special way.
+ */
+unsigned
+utf8_widthis(char *str)
+{
+    unsigned width = 0;
+    int this_width;
+    UCS ucs;
+    unsigned long remaining_octets;
+    char *readptr;
+
+    if(!(str && *str))
+      return(width);
+
+    readptr = str;
+    remaining_octets = readptr ? strlen(readptr) : 0;
+
+    while(remaining_octets > 0 && *readptr){
+
+	ucs = (UCS) utf8_get((unsigned char **) &readptr, &remaining_octets);
+
+	if(ucs & U8G_ERROR){
+	    /*
+	     * This should not happen, but do something to handle it anyway.
+	     * Treat each character as a single width character, which is what should
+	     * probably happen when we actually go to write it out.
+	     */
+	    remaining_octets--;
+	    readptr++;
+	    this_width = 1;
+	}
+	else{
+	    this_width = (ucs == TAB) ? ((~width & 0x07) + 1) : wcellwidth(ucs);
+
+	    /*
+	     * If this_width is -1 that means we can't print this character
+	     * with our current locale. Writechar will print a '?'.
+	     */
+	    if(this_width < 0)
+	      this_width = 1;
+	}
+
+	width += (unsigned) this_width;
+    }
+
+    return(width);
+}
+
+/*
  * Copy UTF-8 characters from src into dst.
  * This is intended to be used if you want to truncate a string at
  * the start instead of the end. For example, you have a long string