Associate structure tree elements directly to render content

* Defer the binding of PCData to struct elems using a placeholder mechanism.
* Translate text nodes to marked-content sequences in IF structure tree.
* Replace ptr with structure tree element.
* Re-order table footers so they appear at the end of the structure tree.


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_ImproveAccessibility@1236718 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 408 insertions, 0 deletions

diff --git a/src/java/org/apache/fop/accessibility/fo/StructureTreeEventTrigger.java b/src/java/org/apache/fop/accessibility/fo/StructureTreeEventTrigger.java
new file mode 100644
index 000000000..b5cd0a5a4
--- /dev/null
+++ b/src/java/org/apache/fop/accessibility/fo/StructureTreeEventTrigger.java
@@ -0,0 +1,408 @@
+/*
+ * 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.fo;
+
+import java.util.Locale;
+
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.AttributesImpl;
+
+import org.apache.fop.accessibility.StructureTreeElement;
+import org.apache.fop.accessibility.StructureTreeEventHandler;
+import org.apache.fop.fo.FOEventHandler;
+import org.apache.fop.fo.FONode;
+import org.apache.fop.fo.FOText;
+import org.apache.fop.fo.extensions.ExtensionElementMapping;
+import org.apache.fop.fo.flow.AbstractGraphics;
+import org.apache.fop.fo.flow.BasicLink;
+import org.apache.fop.fo.flow.Block;
+import org.apache.fop.fo.flow.BlockContainer;
+import org.apache.fop.fo.flow.Character;
+import org.apache.fop.fo.flow.ExternalGraphic;
+import org.apache.fop.fo.flow.Footnote;
+import org.apache.fop.fo.flow.FootnoteBody;
+import org.apache.fop.fo.flow.Inline;
+import org.apache.fop.fo.flow.InstreamForeignObject;
+import org.apache.fop.fo.flow.ListBlock;
+import org.apache.fop.fo.flow.ListItem;
+import org.apache.fop.fo.flow.ListItemBody;
+import org.apache.fop.fo.flow.ListItemLabel;
+import org.apache.fop.fo.flow.PageNumber;
+import org.apache.fop.fo.flow.PageNumberCitation;
+import org.apache.fop.fo.flow.PageNumberCitationLast;
+import org.apache.fop.fo.flow.Wrapper;
+import org.apache.fop.fo.flow.table.Table;
+import org.apache.fop.fo.flow.table.TableBody;
+import org.apache.fop.fo.flow.table.TableCell;
+import org.apache.fop.fo.flow.table.TableFooter;
+import org.apache.fop.fo.flow.table.TableHeader;
+import org.apache.fop.fo.flow.table.TableRow;
+import org.apache.fop.fo.pagination.Flow;
+import org.apache.fop.fo.pagination.PageSequence;
+import org.apache.fop.fo.pagination.StaticContent;
+import org.apache.fop.fo.properties.CommonAccessibilityHolder;
+import org.apache.fop.util.XMLUtil;
+
+/**
+ * A bridge between {@link FOEventHandler} and {@link StructureTreeEventHandler}.
+ */
+class StructureTreeEventTrigger extends FOEventHandler {
+
+    private StructureTreeEventHandler structureTreeEventHandler;
+
+    public StructureTreeEventTrigger(StructureTreeEventHandler structureTreeEventHandler) {
+        this.structureTreeEventHandler = structureTreeEventHandler;
+    }
+
+    @Override
+    public void startDocument() throws SAXException {
+    }
+
+    @Override
+    public void endDocument() throws SAXException {
+    }
+
+    @Override
+    public void startPageSequence(PageSequence pageSeq) {
+        Locale locale = null;
+        if (pageSeq.getLanguage() != null) {
+            if (pageSeq.getCountry() != null) {
+                locale = new Locale(pageSeq.getLanguage(), pageSeq.getCountry());
+            } else {
+                locale = new Locale(pageSeq.getLanguage());
+            }
+        }
+        structureTreeEventHandler.startPageSequence(locale);
+    }
+
+    @Override
+    public void endPageSequence(PageSequence pageSeq) {
+        structureTreeEventHandler.endPageSequence();
+    }
+
+    @Override
+    public void startPageNumber(PageNumber pagenum) {
+        startElementWithID(pagenum);
+    }
+
+    @Override
+    public void endPageNumber(PageNumber pagenum) {
+        endElement(pagenum);
+    }
+
+    @Override
+    public void startPageNumberCitation(PageNumberCitation pageCite) {
+        startElementWithID(pageCite);
+    }
+
+    @Override
+    public void endPageNumberCitation(PageNumberCitation pageCite) {
+        endElement(pageCite);
+    }
+
+    @Override
+    public void startPageNumberCitationLast(PageNumberCitationLast pageLast) {
+        startElementWithID(pageLast);
+    }
+
+    @Override
+    public void endPageNumberCitationLast(PageNumberCitationLast pageLast) {
+        endElement(pageLast);
+    }
+
+    @Override
+    public void startFlow(Flow fl) {
+        startElement(fl);
+    }
+
+    @Override
+    public void endFlow(Flow fl) {
+        endElement(fl);
+    }
+
+    @Override
+    public void startBlock(Block bl) {
+        startElement(bl);
+    }
+
+    @Override
+    public void endBlock(Block bl) {
+        endElement(bl);
+    }
+
+    @Override
+    public void startBlockContainer(BlockContainer blc) {
+        startElement(blc);
+    }
+
+    @Override
+    public void endBlockContainer(BlockContainer blc) {
+        endElement(blc);
+    }
+
+    @Override
+    public void startInline(Inline inl) {
+        startElement(inl);
+    }
+
+    @Override
+    public void endInline(Inline inl) {
+        endElement(inl);
+    }
+
+    @Override
+    public void startTable(Table tbl) {
+        startElement(tbl);
+    }
+
+    @Override
+    public void endTable(Table tbl) {
+        endElement(tbl);
+    }
+
+    @Override
+    public void startHeader(TableHeader header) {
+        startElement(header);
+    }
+
+    @Override
+    public void endHeader(TableHeader header) {
+        endElement(header);
+    }
+
+    @Override
+    public void startFooter(TableFooter footer) {
+        startElement(footer);
+    }
+
+    @Override
+    public void endFooter(TableFooter footer) {
+        endElement(footer);
+    }
+
+    @Override
+    public void startBody(TableBody body) {
+        startElement(body);
+    }
+
+    @Override
+    public void endBody(TableBody body) {
+        endElement(body);
+    }
+
+    @Override
+    public void startRow(TableRow tr) {
+        startElement(tr);
+    }
+
+    @Override
+    public void endRow(TableRow tr) {
+        endElement(tr);
+    }
+
+    @Override
+    public void startCell(TableCell tc) {
+        AttributesImpl attributes = new AttributesImpl();
+        int colSpan = tc.getNumberColumnsSpanned();
+        if (colSpan > 1) {
+            addNoNamespaceAttribute(attributes, "number-columns-spanned",
+                    Integer.toString(colSpan));
+        }
+        startElement(tc, attributes);
+    }
+
+    @Override
+    public void endCell(TableCell tc) {
+        endElement(tc);
+    }
+
+    @Override
+    public void startList(ListBlock lb) {
+        startElement(lb);
+    }
+
+    @Override
+    public void endList(ListBlock lb) {
+        endElement(lb);
+    }
+
+    @Override
+    public void startListItem(ListItem li) {
+        startElement(li);
+    }
+
+    @Override
+    public void endListItem(ListItem li) {
+        endElement(li);
+    }
+
+    @Override
+    public void startListLabel(ListItemLabel listItemLabel) {
+        startElement(listItemLabel);
+    }
+
+    @Override
+    public void endListLabel(ListItemLabel listItemLabel) {
+        endElement(listItemLabel);
+    }
+
+    @Override
+    public void startListBody(ListItemBody listItemBody) {
+        startElement(listItemBody);
+    }
+
+    @Override
+    public void endListBody(ListItemBody listItemBody) {
+        endElement(listItemBody);
+    }
+
+    @Override
+    public void startStatic(StaticContent staticContent) {
+        startElement(staticContent);
+    }
+
+    @Override
+    public void endStatic(StaticContent statisContent) {
+        endElement(statisContent);
+    }
+
+    @Override
+    public void startLink(BasicLink basicLink) {
+        startElementWithID(basicLink);
+    }
+
+    @Override
+    public void endLink(BasicLink basicLink) {
+        endElement(basicLink);
+    }
+
+    @Override
+    public void image(ExternalGraphic eg) {
+        startElementWithIDAndAltText(eg);
+        endElement(eg);
+    }
+
+    @Override
+    public void startInstreamForeignObject(InstreamForeignObject ifo) {
+        startElementWithIDAndAltText(ifo);
+    }
+
+    @Override
+    public void endInstreamForeignObject(InstreamForeignObject ifo) {
+        endElement(ifo);
+    }
+
+    @Override
+    public void startFootnote(Footnote footnote) {
+        startElement(footnote);
+    }
+
+    @Override
+    public void endFootnote(Footnote footnote) {
+        endElement(footnote);
+    }
+
+    @Override
+    public void startFootnoteBody(FootnoteBody body) {
+        startElement(body);
+    }
+
+    @Override
+    public void endFootnoteBody(FootnoteBody body) {
+        endElement(body);
+    }
+
+    @Override
+    public void startWrapper(Wrapper wrapper) {
+        startElement(wrapper);
+    }
+
+    @Override
+    public void endWrapper(Wrapper wrapper) {
+        endElement(wrapper);
+    }
+
+    @Override
+    public void character(Character c) {
+        startElementWithID(c);
+        endElement(c);
+    }
+
+    @Override
+    public void characters(FOText foText) {
+        startElementWithID(foText);
+        endElement(foText);
+    }
+
+
+    private void startElement(FONode node) {
+        startElement(node, new AttributesImpl());
+    }
+
+    private void startElementWithID(FONode node) {
+        AttributesImpl attributes = new AttributesImpl();
+        String localName = node.getLocalName();
+        if (node instanceof CommonAccessibilityHolder) {
+            addRole((CommonAccessibilityHolder) node, attributes);
+        }
+        node.setStructureTreeElement(structureTreeEventHandler.startReferencedNode(localName, attributes));
+    }
+
+    private void startElementWithIDAndAltText(AbstractGraphics node) {
+        AttributesImpl attributes = new AttributesImpl();
+        String localName = node.getLocalName();
+        addRole(node, attributes);
+        addAttribute(attributes, ExtensionElementMapping.URI, "alt-text",
+                ExtensionElementMapping.STANDARD_PREFIX, node.getAltText());
+        node.setStructureTreeElement(structureTreeEventHandler.startImageNode(localName, attributes));
+    }
+
+    private StructureTreeElement startElement(FONode node, AttributesImpl attributes) {
+        String localName = node.getLocalName();
+        if (node instanceof CommonAccessibilityHolder) {
+            addRole((CommonAccessibilityHolder) node, attributes);
+        }
+        return structureTreeEventHandler.startNode(localName, attributes);
+    }
+
+    private void addNoNamespaceAttribute(AttributesImpl attributes, String name, String value) {
+        attributes.addAttribute("", name, name, XMLUtil.CDATA, value);
+    }
+
+    private void addAttribute(AttributesImpl attributes,
+            String namespace, String localName, String prefix, String value) {
+        assert namespace.length() > 0 && prefix.length() > 0;
+        String qualifiedName = prefix + ":" + localName;
+        attributes.addAttribute(namespace, localName, qualifiedName, XMLUtil.CDATA, value);
+    }
+
+    private void addRole(CommonAccessibilityHolder node, AttributesImpl attributes) {
+        String role = node.getCommonAccessibility().getRole();
+        if (role != null) {
+            addNoNamespaceAttribute(attributes, "role", role);
+        }
+    }
+
+    private void endElement(FONode node) {
+        String localName = node.getLocalName();
+        structureTreeEventHandler.endNode(localName);
+    }
+
+}