Allow font cache to be cleared

DEVSIX-3216

Autoported commit.
Original commit hash: [c2b2e7f65]

Author: yulian-gaponenko

itext.tests/itext.io.tests/itext/io/font/FontCacheTest.cs

@@ -0,0 +1,28 @@
+using System;
+using iText.IO.Font.Otf;
+using iText.Test;
+
+namespace iText.IO.Font {
+    public class FontCacheTest : ExtendedITextTest {
+        [NUnit.Framework.Test]
+        public virtual void ClearFontCacheTest() {
+            String fontName = "FreeSans.ttf";
+            NUnit.Framework.Assert.IsNull(FontCache.GetFont(fontName));
+            FontProgram fontProgram = new FontCacheTest.FontProgramMock();
+            FontCache.SaveFont(fontProgram, fontName);
+            NUnit.Framework.Assert.AreEqual(fontProgram, FontCache.GetFont(fontName));
+            FontCache.ClearSavedFonts();
+            NUnit.Framework.Assert.IsNull(FontCache.GetFont(fontName));
+        }
+
+        private class FontProgramMock : FontProgram {
+            public override int GetPdfFontFlags() {
+                return 0;
+            }
+
+            public override int GetKerning(Glyph first, Glyph second) {
+                return 0;
+            }
+        }
+    }
+}

itext/itext.io/itext/io/font/FontCache.cs

@@ -150,6 +150,22 @@ public static CMapCidByte GetCid2Byte(String cmap) {
             return ParseCmap(cmap, cidByte);
         }
 
+        /// <summary>
+        /// Clears the cache by removing fonts that were added via
+        /// <see cref="SaveFont(FontProgram, System.String)"/>
+        /// .
+        /// <para />
+        /// Be aware that in multithreading environment this method call will affect the result of
+        /// <see cref="GetFont(System.String)"/>
+        /// .
+        /// This in its turn affects creation of fonts via factories when
+        /// <c>cached</c>
+        /// argument is set to true (which is by default).
+        /// </summary>
+        public static void ClearSavedFonts() {
+            fontCache.Clear();
+        }
+
         public static FontProgram GetFont(String fontName) {
             return fontCache.Get(FontCacheKey.Create(fontName));
         }

port-hash

@@ -1 +1 @@
-3b0d07f7b864be476b654b2344f46cf01fd20131
+c2b2e7f65cb8c55d184420181403551267812a16