Adds some convenience methods.

fl_filename_absolute can no generate a path using arbitrary source paths.
Fl_Menu_ adds find_item_with_user_data and find_item_with_argument
Fl_String adds find(string, start)

10 files changed, 170 insertions, 37 deletions

diff --git a/FL/Fl_Menu_.H b/FL/Fl_Menu_.H
index 66bd9c64c..a30c870ea 100644
--- a/FL/Fl_Menu_.H
+++ b/FL/Fl_Menu_.H
@@ -73,6 +73,8 @@ public:
   const Fl_Menu_Item* picked(const Fl_Menu_Item*);
   const Fl_Menu_Item* find_item(const char *name);
   const Fl_Menu_Item* find_item(Fl_Callback*);
+  const Fl_Menu_Item* find_item_with_user_data(void*);
+  const Fl_Menu_Item* find_item_with_argument(long);
   int find_index(const char *name) const;
   int find_index(const Fl_Menu_Item *item) const;
   int find_index(Fl_Callback *cb) const;
diff --git a/FL/Fl_String.H b/FL/Fl_String.H
index e0280f43c..dc0d8307a 100644
--- a/FL/Fl_String.H
+++ b/FL/Fl_String.H
@@ -113,6 +113,7 @@ public:
   Fl_String &operator+=(const char *src);
   Fl_String &operator+=(const Fl_String &src);
   Fl_String &operator+=(char c);
+  int find(const Fl_String &needle, int start_pos=0) const;
   Fl_String &replace(int at, int n_del, const char *src, int n_ins=npos);
   Fl_String &replace(int at, int n_del, const Fl_String &src);
   Fl_String substr(int pos=0, int n=npos) const;
diff --git a/FL/filename.H b/FL/filename.H
index 3d9da0294..be7e90ead 100644
--- a/FL/filename.H
+++ b/FL/filename.H
@@ -63,7 +63,9 @@ FL_EXPORT Fl_String fl_filename_ext(const Fl_String &filename);
 FL_EXPORT Fl_String fl_filename_setext(const Fl_String &filename, const Fl_String &new_extension);
 FL_EXPORT Fl_String fl_filename_expand(const Fl_String &from);
 FL_EXPORT Fl_String fl_filename_absolute(const Fl_String &from);
+FL_EXPORT Fl_String fl_filename_absolute(const Fl_String &from, const Fl_String &base);
 FL_EXPORT Fl_String fl_filename_relative(const Fl_String &from);
+FL_EXPORT Fl_String fl_filename_relative(const Fl_String &from, const Fl_String &base);
 FL_EXPORT Fl_String fl_getcwd();
 
 #  endif
@@ -75,6 +77,7 @@ FL_EXPORT Fl_String fl_getcwd();
 
 inline char *fl_filename_setext(char *to, const char *ext) { return fl_filename_setext(to, FL_PATH_MAX, ext); }
 inline int fl_filename_expand(char *to, const char *from) { return fl_filename_expand(to, FL_PATH_MAX, from); }
+FL_EXPORT int fl_filename_absolute(char *to, int tolen, const char *from, const char *cwd);
 inline int fl_filename_absolute(char *to, const char *from) { return fl_filename_absolute(to, FL_PATH_MAX, from); }
 FL_EXPORT int fl_filename_relative(char *to, int tolen, const char *from, const char *cwd);
 inline int fl_filename_relative(char *to, const char *from) { return fl_filename_relative(to, FL_PATH_MAX, from); }
diff --git a/src/Fl_Menu_.cxx b/src/Fl_Menu_.cxx
index 28a476e02..1769af9a1 100644
--- a/src/Fl_Menu_.cxx
+++ b/src/Fl_Menu_.cxx
@@ -267,6 +267,40 @@ const Fl_Menu_Item * Fl_Menu_::find_item(Fl_Callback *cb) {
 }
 
 /**
+ Find the menu item for the given user data \p v.
+
+ \param[in] v find the first item with this user data
+ \returns The item found, or NULL if not found
+ \see find_item(const char*)
+ */
+const Fl_Menu_Item* Fl_Menu_::find_item_with_user_data(void *v) {
+  for ( int t=0; t < size(); t++ ) {
+    const Fl_Menu_Item *m = menu_ + t;
+    if (m->user_data_==v) {
+      return m;
+    }
+  }
+  return (const Fl_Menu_Item *)NULL;
+}
+
+/**
+ Find the menu item for the given user argument \p v.
+
+ \param[in] v find the first item with this user argument
+ \returns The item found, or NULL if not found
+ \see find_item(const char*)
+ */
+const Fl_Menu_Item* Fl_Menu_::find_item_with_argument(long v) {
+  for ( int t=0; t < size(); t++ ) {
+    const Fl_Menu_Item *m = menu_ + t;
+    if (m->argument()==v) {
+      return m;
+    }
+  }
+  return (const Fl_Menu_Item *)NULL;
+}
+
+/**
   The value is the index into menu() of the last item chosen by
   the user.  It is zero initially.  You can set it as an integer, or set
   it with a pointer to a menu item.  The set routines return non-zero if
diff --git a/src/Fl_String.cxx b/src/Fl_String.cxx
index 693a88286..e285519ff 100644
--- a/src/Fl_String.cxx
+++ b/src/Fl_String.cxx
@@ -466,6 +466,21 @@ Fl_String &Fl_String::operator+=(char c) {
 }
 
 /**
+ Find a string inside this string.
+ \param[in] needle    find this string
+ \param[in] start_pos start looking at this position
+ \return the offset of the text inside this string, if it was found
+ \return Fl_String::npos if the needle was not found
+ */
+int Fl_String::find(const Fl_String &needle, int start_pos) const {
+  if ((start_pos < 0) || (start_pos >= size_)) return npos;
+  const char *haystack = data() + start_pos;
+  const char *found = strstr(haystack, needle.c_str());
+  if (!found) return npos;
+  return (int)(found - data());
+}
+
+/**
  Replace part of the string with a C-style string or data.
  \param[in] at    erase and insert at this index
  \param[in] n_del number of bytes to erase
diff --git a/src/Fl_System_Driver.H b/src/Fl_System_Driver.H
index 89110b201..e7230f74e 100644
--- a/src/Fl_System_Driver.H
+++ b/src/Fl_System_Driver.H
@@ -134,7 +134,7 @@ public:
   // the default implementation of filename_relative() is in src/filename_absolute.cxx and may be enough
   virtual int filename_relative(char *to, int tolen, const char *from, const char *base);
   // the default implementation of filename_absolute() is in src/filename_absolute.cxx and may be enough
-  virtual int filename_absolute(char *to, int tolen, const char *from);
+  virtual int filename_absolute(char *to, int tolen, const char *from, const char *base);
   // the default implementation of filename_isdir() is in src/filename_isdir.cxx and may be enough
   virtual int filename_isdir(const char* n);
   // the default implementation of filename_isdir_quick() is in src/filename_isdir.cxx and may be enough
diff --git a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.H
index 10047b632..aae1017e2 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.H
@@ -74,7 +74,7 @@ public:
                             char *errmsg=NULL, int errmsg_sz=0) FL_OVERRIDE;
   int filename_expand(char *to,int tolen, const char *from) FL_OVERRIDE;
   int filename_relative(char *to, int tolen, const char *from, const char *base) FL_OVERRIDE;
-  int filename_absolute(char *to, int tolen, const char *from) FL_OVERRIDE;
+  int filename_absolute(char *to, int tolen, const char *from, const char *base) FL_OVERRIDE;
   int filename_isdir(const char *n) FL_OVERRIDE;
   int filename_isdir_quick(const char *n) FL_OVERRIDE;
   const char *filename_ext(const char *buf) FL_OVERRIDE;
diff --git a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
index cda8c1b36..c2d41f98e 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
@@ -636,21 +636,17 @@ Fl_WinAPI_System_Driver::filename_relative(char *to,    // O - Relative filename
   return 1;
 }
 
-int Fl_WinAPI_System_Driver::filename_absolute(char *to, int tolen, const char *from) {
-  if (isdirsep(*from) || *from == '|' || from[1]==':') {
+int Fl_WinAPI_System_Driver::filename_absolute(char *to, int tolen, const char *from, const char *base) {
+  if (isdirsep(*from) || *from == '|' || from[1]==':' || !base) {
     strlcpy(to, from, tolen);
     return 0;
   }
   char *a;
   char *temp = new char[tolen];
   const char *start = from;
-  a = getcwd(temp, tolen);
-  if (!a) {
-    strlcpy(to, from, tolen);
-    delete[] temp;
-    return 0;
-  }
+  strlcpy(temp, base, tolen);
   for (a = temp; *a; a++) if (*a=='\\') *a = '/'; // ha ha
+  /* remove trailing '/' in current working directory */
   if (isdirsep(*(a-1))) a--;
   /* remove intermediate . and .. names: */
   while (*start == '.') {
diff --git a/src/filename_absolute.cxx b/src/filename_absolute.cxx
index 8d016c991..70b86fcf7 100644
--- a/src/filename_absolute.cxx
+++ b/src/filename_absolute.cxx
@@ -1,7 +1,7 @@
 //
 // Filename expansion routines for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2017 by Bill Spitzak and others.
+// Copyright 1998-2023 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -30,7 +30,7 @@
 
 static inline int isdirsep(char c) {return c == '/';}
 
-/** Makes a filename absolute from a relative filename.
+/** Makes a filename absolute from a relative filename to the current working directory.
     \code
     #include <FL/filename.H>
     [..]
@@ -45,30 +45,46 @@ static inline int isdirsep(char c) {return c == '/';}
     \return 0 if no change, non zero otherwise
  */
 int fl_filename_absolute(char *to, int tolen, const char *from) {
-  return Fl::system_driver()->filename_absolute(to, tolen, from);
+  char cwd_buf[FL_PATH_MAX];    // Current directory
+  // get the current directory and return if we can't
+  if (!fl_getcwd(cwd_buf, sizeof(cwd_buf))) {
+    strlcpy(to, from, tolen);
+    return 0;
+  }
+  return Fl::system_driver()->filename_absolute(to, tolen, from, cwd_buf);
 }
 
+/** Concatenate the absolute path `base` with `from` to form the new absolute path in `to`.
+ \code
+ #include <FL/filename.H>
+ char out[FL_PATH_MAX];
+ fl_filename_absolute(out, sizeof(out), "../foo.txt", "/var/tmp");   // out="/var/foo.txt"
+ fl_filename_absolute(out, sizeof(out), "../local/bin", "/usr/bin");  // out="/usr/local/bin"
+ \endcode
+ \param[out] to resulting absolute filename
+ \param[in]  tolen size of the absolute filename buffer
+ \param[in]  from relative filename
+ \param[in]  base `from` is relative to this absolute file path
+ \return 0 if no change, non zero otherwise
+ */
+int fl_filename_absolute(char *to, int tolen, const char *from, const char *base) {
+  return Fl::system_driver()->filename_absolute(to, tolen, from, base);
+}
 
 /**
  \cond DriverDev
  \addtogroup DriverDeveloper
  \{
  */
-
-int Fl_System_Driver::filename_absolute(char *to, int tolen, const char *from) {
-  if (isdirsep(*from) || *from == '|') {
+int Fl_System_Driver::filename_absolute(char *to, int tolen, const char *from, const char *base) {
+  if (isdirsep(*from) || *from == '|' || !base) {
     strlcpy(to, from, tolen);
     return 0;
   }
   char *a;
   char *temp = new char[tolen];
   const char *start = from;
-  a = fl_getcwd(temp, tolen);
-  if (!a) {
-    strlcpy(to, from, tolen);
-    delete[] temp;
-    return 0;
-  }
+  strlcpy(temp, base, tolen);
   a = temp+strlen(temp);
   /* remove trailing '/' in current working directory */
   if (isdirsep(*(a-1))) a--;
@@ -125,10 +141,7 @@ int Fl_System_Driver::filename_absolute(char *to, int tolen, const char *from) {
     \param[in]  from absolute filename
     \return 0 if no change, non zero otherwise
  */
-int                                     // O - 0 if no change, 1 if changed
-fl_filename_relative(char       *to,    // O - Relative filename
-                     int        tolen,  // I - Size of "to" buffer
-                     const char *from)  // I - Absolute filename
+int fl_filename_relative(char *to, int tolen, const char *from)
 {
   char cwd_buf[FL_PATH_MAX];    // Current directory
   // get the current directory and return if we can't
@@ -144,14 +157,10 @@ fl_filename_relative(char       *to,    // O - Relative filename
  \param[out] to resulting relative filename
  \param[in]  tolen size of the relative filename buffer
  \param[in]  from absolute filename
- \param[in]  base relative to this absolute path
+ \param[in]  base generate filename relative to this absolute filename
  \return 0 if no change, non zero otherwise
  */
-int                                     // O - 0 if no change, 1 if changed
-fl_filename_relative(char       *to,    // O - Relative filename
-                     int        tolen,  // I - Size of "to" buffer
-                     const char *from,  // I - Absolute filename
-                     const char *base) { // I - Find path relative to this path
+int fl_filename_relative(char *to, int tolen, const char *from, const char *base) {
   return Fl::system_driver()->filename_relative(to, tolen, from, base);
 }
 
@@ -162,11 +171,7 @@ fl_filename_relative(char       *to,    // O - Relative filename
  \{
  */
 
-int                                             // O - 0 if no change, 1 if changed
-Fl_System_Driver::filename_relative(char *to,   // O - Relative filename
-                     int        tolen,          // I - Size of "to" buffer
-                     const char *from,          // I - Absolute filename
-                     const char *base)          // I - Find path relative to this path
+int Fl_System_Driver::filename_relative(char *to, int tolen, const char *from, const char *base)
 {
   char          *newslash;              // Directory separator
   const char    *slash;                 // Directory separator
@@ -315,6 +320,20 @@ Fl_String fl_filename_absolute(const Fl_String &from) {
 }
 
 /**
+ Append the relative filename `from` to the absolute filename `base` to form
+ the new absolute path.
+ \param[in] from relative filename
+ \param[in] base `from` is relative to this absolute file path
+ \return the new, absolute filename
+ \see fl_filename_absolute(char *to, int tolen, const char *from, const char *base)
+ */
+Fl_String fl_filename_absolute(const Fl_String &from, const Fl_String &base) {
+  char buffer[FL_PATH_MAX];
+  fl_filename_absolute(buffer, FL_PATH_MAX, from.c_str(), base.c_str());
+  return Fl_String(buffer);
+}
+
+/**
  Makes a filename relative to the current working directory.
  \param[in] from file path and name
  \return the new, relative filename
@@ -326,6 +345,19 @@ Fl_String fl_filename_relative(const Fl_String &from) {
   return Fl_String(buffer);
 }
 
+/**
+ Makes a filename relative to any directory.
+ \param[in] from file path and name
+ \param[in] base relative to this absolute path
+ \return the new, relative filename
+ \see fl_filename_relative(char *to, int tolen, const char *from, const char *base)
+ */
+Fl_String fl_filename_relative(const Fl_String &from, const Fl_String &base) {
+  char buffer[FL_PATH_MAX];
+  fl_filename_relative(buffer, FL_PATH_MAX, from.c_str(), base.c_str());
+  return Fl_String(buffer);
+}
+
 /** Cross-platform function to get the current working directory
  as a UTF-8 encoded value in an Fl_String.
  \return the CWD encoded as UTF-8
diff --git a/test/unittest_core.cxx b/test/unittest_core.cxx
index baccdbd04..6091dd7b4 100644
--- a/test/unittest_core.cxx
+++ b/test/unittest_core.cxx
@@ -243,6 +243,56 @@ TEST(Fl_Preferences, Strings) {
   return true;
 }
 
+TEST(fl_filename, ext) {
+  Fl_String r = fl_filename_ext("test.txt");
+  EXPECT_STREQ(r.c_str(), ".txt");
+  r = fl_filename_ext("test");
+  EXPECT_STREQ(r.c_str(), "");
+  r = fl_filename_ext("");
+  EXPECT_STREQ(r.c_str(), "");
+  return true;
+}
+
+TEST(fl_filename, setext) {
+  Fl_String r = fl_filename_setext(Fl_String("test.txt"), ".rtf");
+  EXPECT_STREQ(r.c_str(), "test.rtf");
+  r = fl_filename_setext(Fl_String("test"), ".rtf");
+  EXPECT_STREQ(r.c_str(), "test.rtf");
+  r = fl_filename_setext(Fl_String("test.txt"), "");
+  EXPECT_STREQ(r.c_str(), "test");
+  r = fl_filename_setext(Fl_String(""), ".rtf");
+  EXPECT_STREQ(r.c_str(), ".rtf");
+  r = fl_filename_setext(Fl_String("path/test"), ".rtf");
+  EXPECT_STREQ(r.c_str(), "path/test.rtf");
+  return true;
+}
+
+TEST(fl_filename, relative) {
+  Fl_String base = "/var/tmp/somedir";
+  Fl_String r = fl_filename_relative("/var/tmp/somedir/foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "foo.txt");
+  r = fl_filename_relative("/var/tmp/foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "../foo.txt");
+  r = fl_filename_relative("./foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "./foo.txt");
+  r = fl_filename_relative("../foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "../foo.txt");
+  return true;
+  }
+
+TEST(fl_filename, absolute) {
+  Fl_String base = "/var/tmp/somedir";
+  Fl_String r = fl_filename_absolute("foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "/var/tmp/somedir/foo.txt");
+  r = fl_filename_absolute("/var/tmp/foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "/var/tmp/foo.txt");
+  r = fl_filename_absolute("./foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "/var/tmp/somedir/foo.txt");
+  r = fl_filename_absolute("../foo.txt", base);
+  EXPECT_STREQ(r.c_str(), "/var/tmp/foo.txt");
+  return true;
+}
+
 bool cb1a_ok = false, cb1b_ok = false, cb1c_ok = false;
 int cb1_alloc = 0;
 class MyString : public Fl_String {