Expose some font utility API for public usage

DEVSIX-5101

Autoported commit.
Original commit hash: [9fadebfb1]

Author: Artyom Yanchevsky

itext/itext.kernel/itext/kernel/font/DocTrueTypeFont.cs

@@ -50,7 +50,7 @@ source product.
 using iText.Kernel.Pdf;
 
 namespace iText.Kernel.Font {
-    internal class DocTrueTypeFont : TrueTypeFont, IDocFontProgram {
+    public class DocTrueTypeFont : TrueTypeFont, IDocFontProgram {
         private PdfStream fontFile;
 
         private PdfName fontFileName;

itext/itext.kernel/itext/kernel/font/FontUtil.cs

@@ -51,10 +51,19 @@ source product.
 using iText.Kernel.Pdf;
 
 namespace iText.Kernel.Font {
-    internal class FontUtil {
+    public class FontUtil {
         private static readonly Dictionary<String, CMapToUnicode> uniMaps = new Dictionary<String, CMapToUnicode>(
             );
 
+        public static String AddRandomSubsetPrefixForFontName(String fontName) {
+            StringBuilder newFontName = new StringBuilder(fontName.Length + 7);
+            for (int k = 0; k < 6; ++k) {
+                newFontName.Append((char)(JavaUtil.Random() * 26 + 'A'));
+            }
+            newFontName.Append('+').Append(fontName);
+            return newFontName.ToString();
+        }
+
         internal static CMapToUnicode ProcessToUnicode(PdfObject toUnicode) {
             CMapToUnicode cMapToUnicode = null;
             if (toUnicode is PdfStream) {

itext/itext.kernel/itext/kernel/font/PdfFont.cs

@@ -43,10 +43,8 @@ source product.
 */
 using System;
 using System.Collections.Generic;
-using System.Text;
 using iText.IO.Font;
 using iText.IO.Font.Otf;
-using iText.IO.Util;
 using iText.Kernel;
 using iText.Kernel.Pdf;
 
@@ -533,11 +531,7 @@ protected internal override bool IsWrappedObjectMustBeIndirect() {
         /// </returns>
         protected internal static String UpdateSubsetPrefix(String fontName, bool isSubset, bool isEmbedded) {
             if (isSubset && isEmbedded) {
-                StringBuilder s = new StringBuilder(fontName.Length + 7);
-                for (int k = 0; k < 6; ++k) {
-                    s.Append((char)(JavaUtil.Random() * 26 + 'A'));
-                }
-                return s.Append('+').Append(fontName).ToString();
+                return FontUtil.AddRandomSubsetPrefixForFontName(fontName);
             }
             return fontName;
         }

port-hash

@@ -1 +1 @@
-21c9b38db565d1815041438f2c8b6e1d6b1a2e7e
+9fadebfb114a7ee9ef9058a8b0c9deec71262210