FOP-3342: A script's default language system shared with a named one is kept under dflt

fop-core/src/main/java/org/apache/fop/complexscripts/fonts/OTFAdvancedTypographicTableReader.java

@@ -197,10 +197,12 @@ private void readScriptTable(OFTableName tableTag, long scriptTable, String scri
                 }
                 lta[i] = lt;
                 loa[i] = lo;
-                if (dl == lo) {
-                    dl = 0;
-                    dt = lt;
-                }
+                // The default language system is read under "dflt" even when its table is the one a
+                // named language system record points at. A font builder shares the table whenever a
+                // language's features equal the default's (FontForge does, for DejaVu and others), and
+                // aliasing the default to that language left the script with no default language
+                // system at all, so a caller asking for (script, dflt) fell through to DFLT and lost
+                // the script's features.
                 ll.add(lt);
             }
             // read non-default language system tables

fop-core/src/test/java/org/apache/fop/fonts/SharedDefaultLanguageSystemTestCase.java

@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* $Id$ */
+
+package org.apache.fop.fonts;
+
+import java.io.File;
+
+import org.junit.Before;
+import org.junit.Test;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import org.apache.fop.apps.io.InternalResourceResolver;
+import org.apache.fop.apps.io.ResourceResolverFactory;
+import org.apache.fop.complexscripts.fonts.GlyphPositioningTable;
+import org.apache.fop.complexscripts.fonts.GlyphTable;
+
+/**
+ * DejaVuLGCSerif's GPOS {@code latn} script points its default language system and its {@code AZE}
+ * system at one table, as FontForge does for every language whose features equal the default's,
+ * and GPOS has no {@code DFLT} script. The reader used to alias the default to the named language
+ * and register nothing under {@code dflt}, so a request for the script's default found no kern
+ * feature and the font was never kerned under a default language (FOP-3342). The GSUB side of the same font
+ * does not share its table, which is why ligatures never showed the defect.
+ */
+public class SharedDefaultLanguageSystemTestCase {
+
+    private MultiByteFont font;
+
+    @Before
+    public void setUp() throws Exception {
+        InternalResourceResolver resolver =
+                ResourceResolverFactory.createDefaultInternalResourceResolver(new File(".").toURI());
+        File file = new File("test/resources/fonts/ttf/DejaVuLGCSerif.ttf");
+        CustomFont loaded = FontLoader.loadFont(new FontUris(file.toURI(), null), "", true,
+                EmbeddingMode.AUTO, EncodingMode.AUTO, true, true, resolver, false, false, true);
+        assertTrue(loaded instanceof MultiByteFont);
+        font = (MultiByteFont) loaded;
+        assertTrue(font.performsPositioning());
+    }
+
+    @Test
+    public void testSharedDefaultLanguageSystemIsRegisteredUnderDflt() {
+        assertTrue(font.getGPOS().matchLookupSpecs("latn", "dflt", "kern").size() > 0);
+        assertTrue(font.getGPOS().matchLookupSpecs("latn", "AZE", "kern").size() > 0);
+        assertTrue(font.hasFeature(GlyphTable.GLYPH_TABLE_TYPE_POSITIONING, "latn", "dflt", "kern"));
+    }
+
+    @Test
+    public void testSharedDefaultLanguageSystemKerns() {
+        int[][] gpa = font.performPositioning("AV", "latn", "dflt", 1000);
+        assertNotNull(gpa);
+        assertTrue(gpa[0][GlyphPositioningTable.Value.IDX_X_ADVANCE] < 0);
+    }
+}