Fix font selection in case diacritic font doesn't contain previous symbol

DEVSIX-8285

Author: introfog

layout/src/main/java/com/itextpdf/layout/font/selectorstrategy/AbstractFontSelectorStrategy.java

@@ -112,9 +112,13 @@ public List<Tuple2<GlyphLine, PdfFont>> getGlyphLines(String text) {
                     if (i > indexDiacritic) {
                         if (TextUtil.isDiacritic(codePoint)) {
                             final PdfFont diacriticFont = matchFont(codePoint, fontSelector, fontProvider, additionalFonts);
+                            // Diacritic font must contain previous symbol, if not, don't
+                            // enable special logic for diacritic and process it as usual symbol
+                            boolean isPreviousMatchFont =
+                                    i == 0 || diacriticFont == null || diacriticFont.containsGlyph(extractCodePoint(text, i - 1));
                             // If diacritic font equals to the current font or null, don't
                             // enable special logic for diacritic and process it as usual symbol
-                            if (diacriticFont != null && diacriticFont != currentFont) {
+                            if (diacriticFont != null && diacriticFont != currentFont && isPreviousMatchFont) {
                                 // If it's the first diacritic in a row, we want to break to try to find a better font for
                                 // the previous letter during the next iteration
                                 if (indexDiacritic != i - 1) {

layout/src/test/java/com/itextpdf/layout/font/selectorstrategy/BestMatchFontSelectorStrategyTest.java

@@ -26,7 +26,6 @@ This file is part of the iText (R) project.
 import com.itextpdf.io.font.otf.GlyphLine;
 import com.itextpdf.kernel.font.PdfFont;
 import com.itextpdf.layout.font.selectorstrategy.BestMatchFontSelectorStrategy.BestMatchFontSelectorStrategyFactory;
-import com.itextpdf.layout.font.selectorstrategy.FirstMatchFontSelectorStrategy.FirstMathFontSelectorStrategyFactory;
 import com.itextpdf.test.ExtendedITextTest;
 import com.itextpdf.test.annotations.type.UnitTest;
 
@@ -66,7 +65,7 @@ public void oneDiacriticTest() {
 
     @Test
     public void oneDiacriticWithUnsupportedFontTest() {
-        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithTNR(new FirstMathFontSelectorStrategyFactory());
+        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithTNR(new BestMatchFontSelectorStrategyFactory());
 
         final List<Tuple2<GlyphLine, PdfFont>> result = strategy.getGlyphLines(
                 "L with accent: \u004f\u0302 abc");
@@ -78,9 +77,27 @@ public void oneDiacriticWithUnsupportedFontTest() {
         Assert.assertEquals(result.get(0).getSecond(), result.get(1).getSecond());
     }
 
+    @Test
+    public void diacriticFontDoesnotContainPreviousSymbolTest() {
+        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithNotoSans(new BestMatchFontSelectorStrategyFactory());
+
+        final List<Tuple2<GlyphLine, PdfFont>> result = strategy.getGlyphLines(
+                "Ми\u0301ръ (mírə)");
+        Assert.assertEquals(6, result.size());
+        Assert.assertEquals("Ми", result.get(0).getFirst().toString());
+        Assert.assertEquals("\u0301", result.get(1).getFirst().toString());
+        Assert.assertEquals("ръ", result.get(2).getFirst().toString());
+        Assert.assertEquals(" (mír", result.get(3).getFirst().toString());
+        Assert.assertEquals("ə", result.get(4).getFirst().toString());
+        Assert.assertEquals(")", result.get(5).getFirst().toString());
+        Assert.assertEquals(result.get(0).getSecond(), result.get(2).getSecond());
+        Assert.assertEquals(result.get(2).getSecond(), result.get(3).getSecond());
+    }
+
+
     @Test
     public void oneDiacriticWithOneSupportedFontTest() {
-        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithFreeSans(new FirstMathFontSelectorStrategyFactory());
+        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithFreeSans(new BestMatchFontSelectorStrategyFactory());
 
         final List<Tuple2<GlyphLine, PdfFont>> result = strategy.getGlyphLines(
                 "L with accent: \u004f\u0302 abc");

layout/src/test/java/com/itextpdf/layout/font/selectorstrategy/FirstMatchFontSelectorStrategyTest.java

@@ -59,6 +59,23 @@ public void oneDiacriticTest() {
         Assert.assertNotEquals(result.get(0).getSecond(), result.get(1).getSecond());
     }
 
+    @Test
+    public void diacriticFontDoesnotContainPreviousSymbolTest() {
+        IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithNotoSans(new FirstMathFontSelectorStrategyFactory());
+
+        final List<Tuple2<GlyphLine, PdfFont>> result = strategy.getGlyphLines(
+                "Ми\u0301ръ (mírə)");
+        Assert.assertEquals(6, result.size());
+        Assert.assertEquals("Ми", result.get(0).getFirst().toString());
+        Assert.assertEquals("\u0301", result.get(1).getFirst().toString());
+        Assert.assertEquals("ръ (", result.get(2).getFirst().toString());
+        Assert.assertEquals("mír", result.get(3).getFirst().toString());
+        Assert.assertEquals("ə", result.get(4).getFirst().toString());
+        Assert.assertEquals(")", result.get(5).getFirst().toString());
+        Assert.assertEquals(result.get(0).getSecond(), result.get(2).getSecond());
+        Assert.assertEquals(result.get(2).getSecond(), result.get(3).getSecond());
+    }
+
     @Test
     public void oneDiacriticWithUnsupportedFontTest() {
         IFontSelectorStrategy strategy = FontSelectorTestsUtil.createStrategyWithTNR(new FirstMathFontSelectorStrategyFactory());

layout/src/test/java/com/itextpdf/layout/font/selectorstrategy/FontSelectorTestsUtil.java

@@ -22,6 +22,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.layout.font.selectorstrategy;
 
+import com.itextpdf.io.font.constants.StandardFontFamilies;
 import com.itextpdf.io.font.constants.StandardFonts;
 import com.itextpdf.layout.font.FontCharacteristics;
 import com.itextpdf.layout.font.FontProvider;
@@ -45,6 +46,18 @@ public static IFontSelectorStrategy createStrategyWithFreeSansAndTNR(IFontSelect
         return fontProvider.createFontSelectorStrategy(fontFamilies, new FontCharacteristics(), null);
     }
 
+    public static IFontSelectorStrategy createStrategyWithNotoSans(IFontSelectorStrategyFactory factory) {
+        FontSet fs = new FontSet();
+        fs.addFont(FONTS_FOLDER + "NotoKufiArabic-Regular.ttf");
+        fs.addFont(FONTS_FOLDER + "NotoSansCJKjp-Regular.otf");
+        fs.addFont(FONTS_FOLDER + "NotoSansCherokee-Regular.ttf");
+        final FontProvider fontProvider = new FontProvider(fs, StandardFontFamilies.TIMES);
+        fontProvider.setFontSelectorStrategyFactory(factory);
+        List<String> fontFamilies = new ArrayList<>();
+        fontFamilies.add("random");
+        return fontProvider.createFontSelectorStrategy(fontFamilies, new FontCharacteristics(), null);
+    }
+
     public static IFontSelectorStrategy createStrategyWithTNR(IFontSelectorStrategyFactory factory) {
         FontSet fs = new FontSet();
         fs.addFont(StandardFonts.TIMES_ROMAN);

layout/src/test/resources/com/itextpdf/layout/fonts/NOTICE.txt

@@ -11,6 +11,9 @@ Please notice that the following fonts are used with the mentioned below license
 * NotoSansThai-Regular - SIL Open Font License v1.1
 * Puritan2 - SIL Open Font License v1.1
 * NotoSansOldItalic-Regular.ttf - SIL Open Font License v1.1. Based on commit 20bc5918912503bc1537a407a694738c33c048aa (07.31.2020) from "https://github.com/googlefonts/noto-fonts"
+* NotoSansCJKjp-Regular.otf - SIL Open Font License v1.1
+* NotoSansCherokee-Regular.ttf - SIL Open Font License v1.1
+* NotoKufiArabic-Regular.ttf - SIL Open Font License v1.1