add util::crop_utf8 (stringutil)

src/util/stringutil.hpp

@@ -17,8 +17,23 @@ namespace util {
 
     uint encode_utf8(uint32_t c, ubyte* bytes);
     uint32_t decode_utf8(uint& size, const char* bytes);
+
+    /// @brief Encode raw wstring to UTF-8
+    /// @param ws source raw wstring
+    /// @return new UTF-8 encoded string
     std::string wstr2str_utf8(const std::wstring& ws);
+
+    /// @brief Decode UTF
+    /// @param s source encoded string
+    /// @return new raw decoded string
     std::wstring str2wstr_utf8(const std::string& s);
+
+    /// @brief Calculated length of UTF-8 encoded string that fits into maxSize
+    /// @param s source UTF-8 encoded string view
+    /// @param maxSize max encoded string length after crop
+    /// @return cropped string size (less or equal to maxSize)
+    size_t crop_utf8(std::string_view s, size_t maxSize);
+    
     bool is_integer(const std::string& text);
     bool is_integer(const std::wstring& text);
     bool is_valid_filename(const std::wstring& name);