Add dStr_shorten() to make strings shorter

Some URLs are very long and would cause long lines when being displayed.
To avoid this problem, we introduce dStr_shorten() to cut them and use
"..." in the middle so they fit in the specified character count.

2 files changed, 42 insertions, 1 deletions

diff --git a/dlib/dlib.c b/dlib/dlib.c
index 2cbd083e..ed967b3a 100644
--- a/dlib/dlib.c
+++ b/dlib/dlib.c
@@ -2,7 +2,7 @@
  * File: dlib.c
  *
  * Copyright (C) 2006-2007 Jorge Arellano Cid <jcid@dillo.org>
- * Copyright (C) 2024 Rodrigo Arias Mallo <rodarima@gmail.com>
+ * Copyright (C) 2024-2025 Rodrigo Arias Mallo <rodarima@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -538,6 +538,34 @@ const char *dStr_printable(Dstr *in, int maxlen)
    return out->str;
 }
 
+/** Shorten string so it fits in n characters.
+ *
+ * Cuts the string src so that it fits in n by replacing the middle of
+ * the string with "...", but leaving both the start and the end.
+ *
+ * The length n must be at least 9. If the src string is already shorter
+ * than n, it is appended as-is.
+ *
+ * The resulting string is appended to out.
+ */
+void dStr_shorten(Dstr *dst, const char *src, int n)
+{
+   if (n < 9)
+      n = 9;
+
+   int len = strlen(src);
+   if (len > n) {
+      int m = n - 3;
+      int n1 = m / 2; /* First half */
+      int n2 = m - n1; /* Second half */
+      dStr_append_l(dst, src, n1);
+      dStr_append(dst, "...");
+      dStr_append(dst, &src[len - n2]);
+   } else {
+      dStr_append(dst, src);
+   }
+}
+
 /*
  *- dList ---------------------------------------------------------------------
  */
diff --git a/dlib/dlib.h b/dlib/dlib.h
index 351294ff..6c4b018a 100644
--- a/dlib/dlib.h
+++ b/dlib/dlib.h
@@ -1,3 +1,15 @@
+/*
+ * File: dlib.h
+ *
+ * Copyright (C) 2006-2007 Jorge Arellano Cid <jcid@dillo.org>
+ * Copyright (C) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ */
+
 #ifndef __DLIB_H__
 #define __DLIB_H__
 
@@ -124,6 +136,7 @@ void dStr_sprintfa (Dstr *ds, const char *format, ...);
 int  dStr_cmp(Dstr *ds1, Dstr *ds2);
 char *dStr_memmem(Dstr *haystack, Dstr *needle);
 const char *dStr_printable(Dstr *in, int maxlen);
+void dStr_shorten(Dstr *dst, const char *src, int n);
 
 /*
  *-- dList --------------------------------------------------------------------