XWPF Themes: allow public access of theme and add helpers for theme fonts (#986)

* allow public access of theme and add helpers for theme fonts

* nit:naming

* add javadoc and tests

* Fix formatting of getMajorFontForScript method

* Refactor font retrieval methods for null checks

* Update XWPFTheme.java

---------

Co-authored-by: PJ Fanning <pjfanning@users.noreply.github.com>

poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTheme.java

@@ -27,7 +27,9 @@ import org.apache.xmlbeans.XmlOptions;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTBaseStyles;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTColor;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTColorScheme;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTFontCollection;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTOfficeStyleSheet;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTSupplementalFont;
 import org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument;
 import org.openxmlformats.schemas.wordprocessingml.x2006.main.*;
 
@@ -67,6 +69,14 @@ public class XWPFTheme extends POIXMLDocumentPart {
         _theme = theme.getXmlObject();
     }
 
+    /**
+     * @return the underlying CTOfficeStyleSheet instance.
+     * @since 6.0.0
+     */
+    public CTOfficeStyleSheet getCTOfficeStyleSheet() {
+        return _theme;
+    }
+
     /**
      *
      * @return name of this theme, e.g. "Office Theme"
@@ -137,8 +147,10 @@ public class XWPFTheme extends POIXMLDocumentPart {
      *
      */
     @SuppressWarnings("WeakerAccess")
-    public String getMajorFont(){
+    public String getMajorFont() {
-        return _theme.getThemeElements().getFontScheme().getMajorFont().getLatin().getTypeface();
+        CTFontCollection majorFonts = getMajorFonts();
+        return majorFonts == null || majorFonts.getLatin() == null ?
+                null : majorFonts.getLatin().getTypeface();
     }
 
     /**
@@ -147,8 +159,62 @@ public class XWPFTheme extends POIXMLDocumentPart {
      *
      */
     @SuppressWarnings("WeakerAccess")
-    public String getMinorFont(){
+    public String getMinorFont() {
-        return _theme.getThemeElements().getFontScheme().getMinorFont().getLatin().getTypeface();
+        CTFontCollection minorFonts = getMinorFonts();
+        return minorFonts == null || minorFonts.getLatin() == null ?
+                null : minorFonts.getLatin().getTypeface();
+    }
+
+    /**
+     * @param script a 4-letter script code, e.g. "Latn", "Jpan"
+     * @return typeface of the major font for the given script
+     * @since 6.0.0
+     */
+    public String getMajorFontForScript(String script) {
+        CTFontCollection majorFonts = getMajorFonts();
+        return majorFonts == null ? null : getFontTypeface(majorFonts, script);
+    }
+
+    /**
+     * @param script a 4-letter script code, e.g. "Latn", "Jpan"
+     * @return typeface of the minor font for the given script
+     * @since 6.0.0
+     */
+    public String getMinorFontForScript(String script) {
+        CTFontCollection minorFonts = getMinorFonts();
+        return minorFonts == null ? null : getFontTypeface(minorFonts, script);
+    }
+
+    private CTFontCollection getMajorFonts() {
+        if (_theme == null
+                || _theme.getThemeElements() == null
+                || _theme.getThemeElements().getFontScheme() == null
+                || _theme.getThemeElements().getFontScheme().getMajorFont() == null) {
+            return null;
+        }
+        return _theme.getThemeElements().getFontScheme().getMajorFont();
+    }
+
+    private CTFontCollection getMinorFonts() {
+        if (_theme == null
+                || _theme.getThemeElements() == null
+                || _theme.getThemeElements().getFontScheme() == null
+                || _theme.getThemeElements().getFontScheme().getMinorFont() == null) {
+            return null;
+        }
+        return _theme.getThemeElements().getFontScheme().getMinorFont();
+    }
+
+    private static String getFontTypeface(CTFontCollection fontCollection, String script) {
+        CTSupplementalFont[] fonts = fontCollection.getFontArray();
+        if (fonts != null) {
+            for (CTSupplementalFont font : fonts) {
+                if (font.getScript() != null && font.getScript().equals(script)) {
+                    return font.getTypeface();
+                }
+            }
+        }
+        return null;
     }
 
     /**

poi-ooxml/src/test/java/org/apache/poi/xwpf/usermodel/TestXWPFTheme.java

@@ -21,11 +21,13 @@ import org.apache.poi.xslf.usermodel.XSLFColor;
 import org.apache.poi.xwpf.XWPFTestDataSamples;
 import org.junit.jupiter.api.Test;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTColor;
+import org.openxmlformats.schemas.drawingml.x2006.main.CTOfficeStyleSheet;
 
 import java.awt.*;
 import java.io.IOException;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 
 public final class TestXWPFTheme {
 
@@ -36,6 +38,11 @@ public final class TestXWPFTheme {
             assertEquals("Office Theme", theme.getName());
             assertEquals("Cambria", theme.getMajorFont());
             assertEquals("Calibri", theme.getMinorFont());
+            assertEquals("Angsana New", theme.getMajorFontForScript("Thai"));
+            assertEquals("Cordia New", theme.getMinorFontForScript("Thai"));
+            CTOfficeStyleSheet styleSheet = theme.getCTOfficeStyleSheet();
+            assertNotNull(styleSheet);
+            assertEquals("Office", styleSheet.getThemeElements().getFontScheme().getName());
             CTColor accent1 = theme.getCTColor("accent1");
             XSLFColor color = new XSLFColor(accent1, null, null, null);
             assertEquals(new Color(79, 129, 189), color.getColor());