Issue an error when attempting to render an intermediate XML file in accessibility mode, but that file wasn't generated with accessibility (i.e., does not contain the structure tree)

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_Accessibility@828747 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 96 insertions, 10 deletions

diff --git a/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.java b/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.java
new file mode 100644
index 000000000..9a74b7ca8
--- /dev/null
+++ b/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.java
@@ -0,0 +1,54 @@
+/*
+ * 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.accessibility;
+
+import org.apache.fop.events.EventBroadcaster;
+import org.apache.fop.events.EventProducer;
+
+/**
+ * Event producer for accessibility-related events.
+ */
+public interface AccessibilityEventProducer extends EventProducer {
+
+    /** Provider class for the event producer. */
+    public final class Provider {
+
+        private Provider() { }
+
+        /**
+         * Returns an event producer.
+         *
+         * @param broadcaster the event broadcaster to use
+         * @return the event producer
+         */
+        public static AccessibilityEventProducer get(EventBroadcaster broadcaster) {
+            return (AccessibilityEventProducer) broadcaster.getEventProducerFor(
+                    AccessibilityEventProducer.class);
+        }
+    }
+
+    /**
+     * The structure tree is missing in the XML file.
+     *
+     * @param source the event source
+     * @event.severity FATAL
+     */
+    void noStructureTreeInXML(Object source);
+}
diff --git a/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.xml b/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.xml
new file mode 100644
index 000000000..70466c2e9
--- /dev/null
+++ b/src/java/org/apache/fop/accessibility/AccessibilityEventProducer.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<catalogue xml:lang="en">
+  <message key="org.apache.fop.accessibility.AccessibilityEventProducer.noStructureTreeInXML">Accessibility is enabled but structure tree is missing in XML file. Please disable accessibility, or re-generate XML file in accessibility mode.</message>
+</catalogue>
diff --git a/src/java/org/apache/fop/area/AreaTreeParser.java b/src/java/org/apache/fop/area/AreaTreeParser.java
index 784ca0684..ffffda7f4 100644
--- a/src/java/org/apache/fop/area/AreaTreeParser.java
+++ b/src/java/org/apache/fop/area/AreaTreeParser.java
@@ -57,6 +57,7 @@ import org.apache.xmlgraphics.image.loader.ImageManager;
 import org.apache.xmlgraphics.image.loader.ImageSessionContext;
 import org.apache.xmlgraphics.util.QName;
 
+import org.apache.fop.accessibility.AccessibilityEventProducer;
 import org.apache.fop.accessibility.StructureTreeBuilder;
 import org.apache.fop.apps.FOUserAgent;
 import org.apache.fop.area.Trait.Background;
@@ -164,19 +165,19 @@ public class AreaTreeParser {
 
         private ContentHandler structureTreeBuilderWrapper;
 
-        private final class StructureTreeBuilderWrapper extends DelegatingContentHandler {
+        private Attributes pageSequenceAttributes;
 
-            private Attributes pageSequenceAttributes;
+        private final class StructureTreeBuilderWrapper extends DelegatingContentHandler {
 
-            private StructureTreeBuilderWrapper(Attributes pageSequenceAttributes)
+            private StructureTreeBuilderWrapper()
                     throws SAXException {
                 super(structureTreeBuilder.getHandlerForNextPageSequence());
-                this.pageSequenceAttributes = new AttributesImpl(pageSequenceAttributes);
             }
 
             public void endDocument() throws SAXException {
                 super.endDocument();
                 startAreaTreeElement("pageSequence", pageSequenceAttributes);
+                pageSequenceAttributes = null;
             }
         }
 
@@ -297,7 +298,8 @@ public class AreaTreeParser {
                 boolean handled = true;
                 if ("".equals(uri)) {
                     if (localName.equals("pageSequence") && userAgent.isAccessibilityEnabled()) {
-                        structureTreeBuilderWrapper = new StructureTreeBuilderWrapper(attributes);
+                        structureTreeBuilderWrapper = new StructureTreeBuilderWrapper();
+                        pageSequenceAttributes = new AttributesImpl(attributes);
                     } else if (localName.equals("structureTree")) {
                         if (userAgent.isAccessibilityEnabled()) {
                             delegate = structureTreeBuilderWrapper;
@@ -309,6 +311,18 @@ public class AreaTreeParser {
                         delegate.startDocument();
                         delegate.startElement(uri, localName, qName, attributes);
                     } else {
+                        if (pageSequenceAttributes != null) {
+                            /*
+                             * This means that no structure-element tag was
+                             * found in the XML, otherwise a
+                             * StructureTreeBuilderWrapper object would have
+                             * been created, which would have reset the
+                             * pageSequenceAttributes field.
+                             */
+                            AccessibilityEventProducer.Provider
+                                    .get(userAgent.getEventBroadcaster())
+                                    .noStructureTreeInXML(this);
+                        }
                         handled = startAreaTreeElement(localName, attributes);
                     }
                 } else {
diff --git a/src/java/org/apache/fop/render/intermediate/IFParser.java b/src/java/org/apache/fop/render/intermediate/IFParser.java
index 45b4816a5..da5d8a623 100644
--- a/src/java/org/apache/fop/render/intermediate/IFParser.java
+++ b/src/java/org/apache/fop/render/intermediate/IFParser.java
@@ -46,6 +46,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.apache.xmlgraphics.util.QName;
 
+import org.apache.fop.accessibility.AccessibilityEventProducer;
 import org.apache.fop.accessibility.StructureTreeBuilder;
 import org.apache.fop.apps.FOUserAgent;
 import org.apache.fop.fo.ElementMapping;
@@ -155,19 +156,19 @@ public class IFParser implements IFConstants {
 
         private ContentHandler structureTreeBuilderWrapper;
 
-        private final class StructureTreeBuilderWrapper extends DelegatingContentHandler {
+        private Attributes pageSequenceAttributes;
 
-            private Attributes pageSequenceAttributes;
+        private final class StructureTreeBuilderWrapper extends DelegatingContentHandler {
 
-            private StructureTreeBuilderWrapper(Attributes pageSequenceAttributes)
+            private StructureTreeBuilderWrapper()
                     throws SAXException {
                 super(structureTreeBuilder.getHandlerForNextPageSequence());
-                this.pageSequenceAttributes = new AttributesImpl(pageSequenceAttributes);
             }
 
             public void endDocument() throws SAXException {
                 super.endDocument();
                 startIFElement(EL_PAGE_SEQUENCE, pageSequenceAttributes);
+                pageSequenceAttributes = null;
             }
         }
 
@@ -227,7 +228,8 @@ public class IFParser implements IFConstants {
                 boolean handled = true;
                 if (NAMESPACE.equals(uri)) {
                     if (localName.equals(EL_PAGE_SEQUENCE) && userAgent.isAccessibilityEnabled()) {
-                        structureTreeBuilderWrapper = new StructureTreeBuilderWrapper(attributes);
+                        pageSequenceAttributes = new AttributesImpl(attributes);
+                        structureTreeBuilderWrapper = new StructureTreeBuilderWrapper();
                     } else if (localName.equals(EL_STRUCTURE_TREE)) {
                         if (userAgent.isAccessibilityEnabled()) {
                             delegate = structureTreeBuilderWrapper;
@@ -239,6 +241,18 @@ public class IFParser implements IFConstants {
                         delegate.startDocument();
                         delegate.startElement(uri, localName, qName, attributes);
                     } else {
+                        if (pageSequenceAttributes != null) {
+                            /*
+                             * This means that no structure-element tag was
+                             * found in the XML, otherwise a
+                             * StructureTreeBuilderWrapper object would have
+                             * been created, which would have reset the
+                             * pageSequenceAttributes field.
+                             */
+                            AccessibilityEventProducer.Provider
+                                    .get(userAgent.getEventBroadcaster())
+                                    .noStructureTreeInXML(this);
+                        }
                         handled = startIFElement(localName, attributes);
                     }
                 } else if (DocumentNavigationExtensionConstants.NAMESPACE.equals(uri)) {