Make lower/upper casing locale independent

DEVSIX-9092

Author: vitali-pr

barcodes/src/main/java/com/itextpdf/barcodes/BarcodeCodabar.java

@@ -23,6 +23,7 @@ This file is part of the iText (R) project.
 package com.itextpdf.barcodes;
 
 import com.itextpdf.barcodes.exceptions.BarcodesExceptionMessageConstant;
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.kernel.colors.Color;
 import com.itextpdf.kernel.font.PdfFont;
 import com.itextpdf.kernel.geom.Rectangle;
@@ -150,7 +151,7 @@ public BarcodeCodabar(PdfDocument document, PdfFont font) {
      * @return the bars
      */
     public static byte[] getBarsCodabar(String text) {
-        text = text.toUpperCase();
+        text = StringNormalizer.toUpperCase(text);
         int len = text.length();
         if (len < 2) {
             throw new IllegalArgumentException(
@@ -186,7 +187,7 @@ public static byte[] getBarsCodabar(String text) {
     public static String calculateChecksum(String code) {
         if (code.length() < 2)
             return code;
-        String text = code.toUpperCase();
+        String text = StringNormalizer.toUpperCase(code);
         int sum = 0;
         int len = text.length();
         for (int k = 0; k < len; ++k) {

commons/src/main/java/com/itextpdf/commons/actions/contexts/ContextManager.java

@@ -24,6 +24,7 @@ This file is part of the iText (R) project.
 
 import com.itextpdf.commons.actions.NamespaceConstant;
 import com.itextpdf.commons.actions.ProductNameConstant;
+import com.itextpdf.commons.utils.StringNormalizer;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -131,7 +132,7 @@ void registerGenericContext(Collection<String> namespaces, Collection<String> pr
 
     private static String normalize(String namespace) {
         // Conversion to lowercase is done to be compatible with possible changes in case of packages/namespaces
-        return namespace.toLowerCase();
+        return StringNormalizer.toLowerCase(namespace);
     }
 
     private static class LengthComparator implements Comparator<String> {

commons/src/main/java/com/itextpdf/commons/utils/StringNormalizer.java

@@ -0,0 +1,77 @@
+/*
+    This file is part of the iText (R) project.
+    Copyright (c) 1998-2025 Apryse Group NV
+    Authors: Apryse Software.
+
+    This program is offered under a commercial and under the AGPL license.
+    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.
+
+    AGPL licensing:
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.itextpdf.commons.utils;
+
+import java.util.Locale;
+
+/**
+ * Utility class for string normalization.
+ */
+public final class StringNormalizer {
+
+    private StringNormalizer() {
+        // Empty constructor
+    }
+
+    /**
+     * Converts a string to lowercase using Root locale.
+     *
+     * @param str a string to convert
+     * @return a converted string
+     */
+    public static String toLowerCase(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        return str.toLowerCase(Locale.ROOT);
+    }
+
+    /**
+     * Converts a string to uppercase using Root locale.
+     *
+     * @param str a string to convert
+     * @return a converted string
+     */
+    public static String toUpperCase(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        return str.toUpperCase(Locale.ROOT);
+    }
+
+    /**
+     * Converts a string to lowercase using Root locale and trims it.
+     *
+     * @param str a string to convert
+     * @return a converted string
+     */
+    public static String normalize(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        return toLowerCase(str).trim();
+    }
+}

commons/src/test/java/com/itextpdf/commons/actions/contexts/ContextManagerTest.java

@@ -23,6 +23,7 @@ This file is part of the iText (R) project.
 package com.itextpdf.commons.actions.contexts;
 
 import com.itextpdf.commons.actions.NamespaceConstant;
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.test.ExtendedITextTest;
 
 import java.util.Arrays;
@@ -37,8 +38,8 @@ public class ContextManagerTest extends ExtendedITextTest {
 
     @Test
     public void getRecognisedNamespaceForSpecificNamespaceTest() {
-        String outerNamespaces = NamespaceConstant.ITEXT.toLowerCase();
-        String innerNamespaces = NamespaceConstant.PDF_HTML.toLowerCase();
+        String outerNamespaces = StringNormalizer.toLowerCase(NamespaceConstant.ITEXT);
+        String innerNamespaces = StringNormalizer.toLowerCase(NamespaceConstant.PDF_HTML);
 
         Assertions.assertTrue(innerNamespaces.startsWith(outerNamespaces));
 
@@ -89,7 +90,7 @@ public void unregisterNamespaceTest() {
 
         Assertions.assertEquals(testNamespace,
                 manager.getRecognisedNamespace(testNamespace + ".MyClass"));
-        Assertions.assertEquals(testNamespaceWithCapitals.toLowerCase(),
+        Assertions.assertEquals(StringNormalizer.toLowerCase(testNamespaceWithCapitals),
                 manager.getRecognisedNamespace(testNamespaceWithCapitals + ".MyClass"));
 
         manager.unregisterContext(testNamespaces);
@@ -102,7 +103,7 @@ public void unregisterNamespaceTest() {
     public void registeredNamespaceTest() {
         String registeredNamespace = NamespaceConstant.CORE_LAYOUT + "custompackage";
 
-        Assertions.assertEquals(NamespaceConstant.CORE_LAYOUT.toLowerCase(),
+        Assertions.assertEquals(StringNormalizer.toLowerCase(NamespaceConstant.CORE_LAYOUT),
                 ContextManager.getInstance().getRecognisedNamespace(registeredNamespace));
     }
 }

commons/src/test/java/com/itextpdf/commons/utils/StringNormalizerTest.java

@@ -0,0 +1,52 @@
+/*
+    This file is part of the iText (R) project.
+    Copyright (c) 1998-2025 Apryse Group NV
+    Authors: Apryse Software.
+
+    This program is offered under a commercial and under the AGPL license.
+    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.
+
+    AGPL licensing:
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.itextpdf.commons.utils;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+
+@Tag("UnitTest")
+public class StringNormalizerTest {
+
+    @Test
+    public void toLowerCaseTest() {
+        Assertions.assertNull(StringNormalizer.toLowerCase(null));
+        Assertions.assertEquals("some string", StringNormalizer.toLowerCase("SoMe StRiNg"));
+        Assertions.assertEquals("some string", StringNormalizer.toLowerCase("SOME STRING"));
+    }
+
+    @Test
+    public void toUpperCaseTest() {
+        Assertions.assertNull(StringNormalizer.toUpperCase(null));
+        Assertions.assertEquals("SOME STRING", StringNormalizer.toUpperCase("SoMe StRiNg"));
+        Assertions.assertEquals("SOME STRING", StringNormalizer.toUpperCase("some string"));
+    }
+
+    @Test
+    public void normalizeTest() {
+        Assertions.assertNull(StringNormalizer.normalize(null));
+        Assertions.assertEquals("some   string", StringNormalizer.normalize(" \t\nSoMe   StRiNg  "));
+        Assertions.assertEquals("some   string", StringNormalizer.normalize(" \t\nSOME   STRING  "));
+    }
+}

forms/src/main/java/com/itextpdf/forms/xfdf/XfdfObjectFactory.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.forms.xfdf;
 
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.forms.PdfAcroForm;
 import com.itextpdf.forms.fields.PdfFormCreator;
 import com.itextpdf.io.logs.IoLogMessageConstant;
@@ -509,7 +510,7 @@ private static void updateXfdfAnnotation(AnnotObject annotObject, PdfAnnotation
     }
 
     private static void addCommonAnnotationAttributes(AnnotObject annot, PdfAnnotation pdfAnnotation) {
-        annot.setName(pdfAnnotation.getSubtype().getValue().toLowerCase());
+        annot.setName(StringNormalizer.toLowerCase(pdfAnnotation.getSubtype().getValue()));
 
         if (pdfAnnotation.getColorObject() != null) {
             annot.addAttribute(new AttributeObject(XfdfConstants.COLOR, XfdfObjectUtils.convertColorToString(pdfAnnotation.getColorObject().toFloatArray())));

forms/src/main/java/com/itextpdf/forms/xfdf/XfdfObjectUtils.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.forms.xfdf;
 
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.io.source.ByteUtils;
 import com.itextpdf.kernel.colors.Color;
 import com.itextpdf.kernel.geom.Rectangle;
@@ -258,7 +259,7 @@ static int convertFlagsFromString(String flagsString) {
         StringTokenizer st = new StringTokenizer(flagsString, delims);
         List<String> flagsList = new ArrayList<>();
         while (st.hasMoreTokens()) {
-            flagsList.add(st.nextToken().toLowerCase());
+            flagsList.add(StringNormalizer.toLowerCase(st.nextToken()));
         }
 
         Map<String, Integer> flagMap = new HashMap<>();
@@ -349,7 +350,7 @@ static String convertColorToString(Color color) {
      * Converts float representation of the rgb color into a hex string representing the rgb color.
      */
     private static String convertColorFloatToHex(float colorFloat) {
-        String result = "0" + Integer.toHexString(((int) (colorFloat * 255 + 0.5))).toUpperCase();
+        String result = "0" + StringNormalizer.toUpperCase(Integer.toHexString(((int) (colorFloat * 255 + 0.5))));
         return result.substring(result.length() - 2);
     }
 
@@ -360,7 +361,7 @@ static String convertIdToHexString(String idString) {
         StringBuilder stb = new StringBuilder();
         char[] stringSymbols = idString.toCharArray();
         for (char ch : stringSymbols) {
-            stb.append(Integer.toHexString((int) ch).toUpperCase());
+            stb.append(StringNormalizer.toUpperCase(Integer.toHexString((int) ch)));
         }
         return stb.toString();
     }

forms/src/main/java/com/itextpdf/forms/xfdf/XfdfReader.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.forms.xfdf;
 
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.forms.PdfAcroForm;
 import com.itextpdf.forms.fields.PdfFormCreator;
 import com.itextpdf.forms.fields.PdfFormField;
@@ -199,7 +200,7 @@ private void addBorderStyleAttributes(PdfAnnotation annotation, AnnotObject anno
             borderStyle.put(PdfName.D, XfdfObjectUtils.convertDashesFromString(dashes));
         }
         if (style != null && !"cloudy".equals(style)) {
-            borderStyle.put(PdfName.S, new PdfName(style.substring(0, 1).toUpperCase()));
+            borderStyle.put(PdfName.S, new PdfName(StringNormalizer.toUpperCase(style.substring(0, 1))));
         }
         if (borderStyle.size() > 0) {
             annotation.put(PdfName.BS, borderStyle);

io/src/main/java/com/itextpdf/io/font/AdobeGlyphList.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.io.font;
 
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.io.font.constants.FontResources;
 import com.itextpdf.io.util.ResourceUtil;
 
@@ -99,7 +100,7 @@ public static int nameToUnicode(String name) {
         if (names2unicode.containsKey(name)) {
             v = (int) names2unicode.get(name);
         }
-        if (v == -1 && name.length() == 7 && name.toLowerCase().startsWith("uni")) {
+        if (v == -1 && name.length() == 7 && StringNormalizer.toLowerCase(name).startsWith("uni")) {
             try {
                 return Integer.parseInt(name.substring(3), 16);
             } catch (Exception ignored) {

io/src/main/java/com/itextpdf/io/font/FontEncoding.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.io.font;
 
+import com.itextpdf.commons.utils.StringNormalizer;
 import com.itextpdf.io.util.ArrayUtil;
 import com.itextpdf.io.util.IntHashtable;
 import com.itextpdf.io.util.TextUtil;
@@ -347,7 +348,7 @@ protected void fillStandardEncoding() {
      * @return the normalized encoding
      */
     protected static String normalizeEncoding(String enc) {
-        String tmp = enc == null ? "" : enc.toLowerCase();
+        String tmp = enc == null ? "" : StringNormalizer.toLowerCase(enc);
         switch (tmp) {
             case "":
             case "winansi":