Bugzilla #46705:

Accessibility and Tagged PDF Support
Submitted by: Jost Klopfstein <jost.klopfstein.at.gmail.com>

Changes to patch by jeremias:
- Some style fixes
- Various simplifications
- Removal of dead code
- Addressed some issues raised in Bugzilla (work in progress)
- Fixed a couple of bugs on leader handling detected while testing (an NPE remains in leader_leader-pattern_use-content.xml)


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_Accessibility@745949 13f79535-47bb-0310-9956-ffa450edef68

9 files changed, 470 insertions, 5 deletions

diff --git a/src/java/org/apache/fop/pdf/PDFArray.java b/src/java/org/apache/fop/pdf/PDFArray.java
index 7c5f8ba9b..a7dfc388e 100644
--- a/src/java/org/apache/fop/pdf/PDFArray.java
+++ b/src/java/org/apache/fop/pdf/PDFArray.java
@@ -107,6 +107,15 @@ public class PDFArray extends PDFObject {
     }
 
     /**
+     * Indicates whether the given object exists in the array.
+     * @param obj the object to look for
+     * @return true if obj is contained
+     */
+    public boolean contains(Object obj) {
+        return this.values.contains(obj);
+    }
+
+    /**
      * Returns the length of the array
      * @return the length of the array
      */
diff --git a/src/java/org/apache/fop/pdf/PDFFactory.java b/src/java/org/apache/fop/pdf/PDFFactory.java
index 0a4516ce6..087ae4277 100644
--- a/src/java/org/apache/fop/pdf/PDFFactory.java
+++ b/src/java/org/apache/fop/pdf/PDFFactory.java
@@ -177,18 +177,26 @@ public class PDFFactory {
      * @param pageWidth width of the page in points
      * @param pageHeight height of the page in points
      * @param pageIndex index of the page (zero-based)
+     * @param currentPageParentKey the integer key in the structural parent tree
      *
      * @return the created /Page object
      */
     public PDFPage makePage(PDFResources resources,
-                            int pageWidth, int pageHeight, int pageIndex) {
-
+                            int pageWidth, int pageHeight, int pageIndex,
+                            int currentPageParentKey) {
         /*
          * create a PDFPage with the next object number, the given
          * resources, contents and dimensions
          */
-        PDFPage page = new PDFPage(resources,
+        PDFPage page = new PDFPage(resources,                       // old numPages
                                    pageWidth, pageHeight, pageIndex);
+        if (currentPageParentKey > -1) {
+            //Accessibility is enabled
+            page.setStructParents(currentPageParentKey);
+            //This is a PDF 1.5 feature. It is set as a work-around for a bug in Adobe Acrobat
+            //which reports this missing even if the PDF file is PDF 1.4.
+            page.setTabs(new PDFName("S"));
+        }
 
         getDocument().assignObjectNumber(page);
         getDocument().getPages().addPage(page);
@@ -203,6 +211,23 @@ public class PDFFactory {
      * @param resources resources object to use
      * @param pageWidth width of the page in points
      * @param pageHeight height of the page in points
+     * @param pageIndex index of the page (zero-based)
+     *
+     * @return the created /Page object
+     */
+    public PDFPage makePage(PDFResources resources,
+                            int pageWidth, int pageHeight, int pageIndex) {
+        return makePage(resources, pageWidth, pageHeight, pageIndex, -1);
+    }
+
+    /**
+     * Make a /Page object. The page is assigned an object number immediately
+     * so references can already be made. The page must be added to the
+     * PDFDocument later using addObject().
+     *
+     * @param resources resources object to use
+     * @param pageWidth width of the page in points
+     * @param pageHeight height of the page in points
      *
      * @return the created /Page object
      */
@@ -868,6 +893,17 @@ public class PDFFactory {
     }
 
     /**
+     * Creates and returns a StructTreeRoot object. Used for accessibility.
+     * @return structure Tree Root element
+     */
+    public PDFStructTreeRoot makeStructTreeRoot() {
+        PDFStructTreeRoot structTreeRoot = new PDFStructTreeRoot();
+        getDocument().assignObjectNumber(structTreeRoot);
+        getDocument().addTrailerObject(structTreeRoot);
+        return structTreeRoot;
+    }
+
+    /**
      * Make a the head object of the name dictionary (the /Dests object).
      *
      * @param destinationList a list of PDFDestination instances
diff --git a/src/java/org/apache/fop/pdf/PDFLink.java b/src/java/org/apache/fop/pdf/PDFLink.java
index a7c4c6548..620e5d51d 100644
--- a/src/java/org/apache/fop/pdf/PDFLink.java
+++ b/src/java/org/apache/fop/pdf/PDFLink.java
@@ -42,6 +42,7 @@ public class PDFLink extends PDFObject {
     private float bry;
     private String color;
     private PDFAction action;
+    private Integer structParent;
 
     /**
      * create objects associated with a link annotation (GoToR)
@@ -68,6 +69,15 @@ public class PDFLink extends PDFObject {
         this.action = action;
     }
 
+
+    /**
+     * Used for accessibility
+     * @param mcid of this structParent
+     */
+    public void setStructParent(int mcid) {
+        this.structParent = new Integer(mcid);
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -87,6 +97,8 @@ public class PDFLink extends PDFObject {
                    + (brx) + " " + (bry) + " ]\n" + "/C [ "
                    + this.color + " ]\n" + "/Border [ 0 0 0 ]\n" + "/A "
                    + this.action.getAction() + "\n" + "/H /I\n"
+                   + (this.structParent != null
+                           ? "/StructParent " + this.structParent.toString() + "\n" : "")
                    + fFlag + "\n>>\nendobj\n";
         return s;
     }
diff --git a/src/java/org/apache/fop/pdf/PDFPage.java b/src/java/org/apache/fop/pdf/PDFPage.java
index d1472e154..6cc8c3e57 100644
--- a/src/java/org/apache/fop/pdf/PDFPage.java
+++ b/src/java/org/apache/fop/pdf/PDFPage.java
@@ -146,4 +146,21 @@ public class PDFPage extends PDFResourceContext {
         return this.pageIndex;
     }
 
+    /**
+     * Sets the "StructParents" value.
+     * @param structParents the integer key of this object's entry in the structural parent tree.
+     */
+    public void setStructParents(int structParents) {
+        put("StructParents", structParents);
+    }
+
+    /**
+     * Specifies the tab order for annotations on a page.
+     * @param value one of the allowed values (see PDF 1.5)
+     * @since PDF 1.5
+     */
+    public void setTabs(PDFName value) {
+        put("Tabs", value);
+    }
+
 }
diff --git a/src/java/org/apache/fop/pdf/PDFParentTree.java b/src/java/org/apache/fop/pdf/PDFParentTree.java
new file mode 100644
index 000000000..7528aa299
--- /dev/null
+++ b/src/java/org/apache/fop/pdf/PDFParentTree.java
@@ -0,0 +1,50 @@
+/*
+ * 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.pdf;
+
+/**
+ * Class representing a PDF /ParentTree
+ */
+public class PDFParentTree extends PDFNumberTreeNode {
+
+    /**
+     * Create the /ParentTree NumberTreeNode
+     */
+    public PDFParentTree() {
+        super();
+    }
+
+    /**
+     * Get the parentTree.
+     * @return parentTree as PDFNumsArray
+     */
+    public PDFNumsArray getNums() {
+        PDFNumsArray nums = super.getNums();
+        if (nums == null) {
+            nums = new PDFNumsArray(this);
+            setNums(nums);
+        }
+        return nums;
+    }
+}
+
+
+
+
diff --git a/src/java/org/apache/fop/pdf/PDFRoot.java b/src/java/org/apache/fop/pdf/PDFRoot.java
index 1ea316390..c8d94585c 100644
--- a/src/java/org/apache/fop/pdf/PDFRoot.java
+++ b/src/java/org/apache/fop/pdf/PDFRoot.java
@@ -63,7 +63,7 @@ public class PDFRoot extends PDFDictionary {
      */
     public PDFRoot(int objnum, PDFPages pages) {
         super();
-        setObjectNumber(objnum);
+         setObjectNumber(objnum);
         put("Type", new PDFName("Catalog"));
         setRootPages(pages);
     }
@@ -252,4 +252,32 @@ public class PDFRoot extends PDFDictionary {
         put("Lang", lang);
     }
 
+    /**
+     * Sets the StructTreeRoot object. Used for accessibility.
+     * @param structTreeRoot of this document
+     */
+    public void setStructTreeRoot(PDFStructTreeRoot structTreeRoot) {
+        if (structTreeRoot == null) {
+            throw new NullPointerException("structTreeRoot must not be null");
+        }
+        put("StructTreeRoot", structTreeRoot);
+    }
+
+    /**
+     * Returns the StructTreeRoot object.
+     * @return the structure tree root (or null if accessibility is not enabled)
+     */
+    public PDFStructTreeRoot getStructTreeRoot() {
+        return (PDFStructTreeRoot)get("StructTreeRoot");
+    }
+
+    /**
+     * Marks this document as conforming to the Tagged PDF conventions.
+     */
+    public void makeTagged() {
+        PDFDictionary dict = new PDFDictionary();
+        dict.put("Marked", Boolean.TRUE);
+        put("MarkInfo", dict);  //new PDFMarkInfo()
+    }
+
 }
diff --git a/src/java/org/apache/fop/pdf/PDFStructElem.java b/src/java/org/apache/fop/pdf/PDFStructElem.java
new file mode 100644
index 000000000..408b1f2c7
--- /dev/null
+++ b/src/java/org/apache/fop/pdf/PDFStructElem.java
@@ -0,0 +1,196 @@
+/*
+ * 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.pdf;
+
+/**
+ * Class representing a PDF Structure Element.
+ */
+public class PDFStructElem extends PDFDictionary {
+
+    private PDFObject parentObject = null;
+    private String source = "";
+    private boolean level1 = false;
+
+    /**
+     * Create the /StructTreeRoot dictionary
+     * @param fo passed in fo object
+     * @param parent Parent of this PDFStructElem
+     */
+    public PDFStructElem(String fo, PDFObject parent) {
+        super();
+        if (parent instanceof PDFStructElem) {
+            parentObject = (PDFStructElem) parent;
+        }
+        put("Type", new PDFName("StructElem"));
+        source = fo;
+        //TODO Move this into the render/pdf package. The PDF library shall not contain FO knowledge
+        if ("block".equals(fo)) {
+            put("S", new PDFName("P"));
+        } else if ("inline".equals(fo) || "wrapper".equals(fo) || "character".equals(fo)) {
+            put("S", new PDFName("Span"));
+        } else if ("table-cell".equals(fo)) {
+            PDFStructElem grandParent = (PDFStructElem)
+                ((PDFStructElem)parent).getParentStructElem();
+            String s = grandParent.getSource();
+            if ("table-header".equals(s)) {
+                put("S", new PDFName("TH"));
+            } else {
+                put("S", new PDFName("TD"));
+            }
+        } else if ("table-row".equals(fo)) {
+            put("S", new PDFName("TR"));
+        } else if ("root".equals(fo)) {
+            put("S", new PDFName("Document"));
+        } else if ("page-sequence".equals(fo)) {
+            put("S", new PDFName("Part"));
+        } else if ("flow".equals(fo) || "static-content".equals(fo)) {
+            put("S", new PDFName("Sect"));
+        }   else if ("page-number".equals(fo) || "page-number-citation".equals(fo)
+                || "page-number-citation-last".equals(fo)) {
+            put("S", new PDFName("Quote"));
+        } else if ("external-graphic".equals(fo) || "instream-foreign-object".equals(fo)) {
+            put("S", new PDFName("Figure"));
+        } else if ("table".equals(fo)) {
+            put("S", new PDFName("Table"));
+        } else if ("table-body".equals(fo)) {
+            put("S", new PDFName("TBody"));
+        } else if ("table-header".equals(fo)) {
+            put("S", new PDFName("THead"));
+        } else if ("table-footer".equals(fo)) {
+            put("S", new PDFName("TFoot"));
+        }  else if ("list-block".equals(fo)) {
+            put("S", new PDFName("L"));
+        } else if ("list-item".equals(fo)) {
+            put("S", new PDFName("LI"));
+        } else if ("list-item-label".equals(fo)) {
+            put("S", new PDFName("Lbl"));
+        } else if ("list-item-body".equals(fo)) {
+            put("S", new PDFName("LBody"));
+        } else if ("block-container".equals(fo)) {
+            put("S", new PDFName("Div"));
+        } else if ("basic-link".equals(fo)) {
+            put("S", new PDFName("Link"));
+        } else if ("footnote".equals(fo)) {
+            put("S", new PDFName("Note"));
+        } else if ("footnote-body".equals(fo)) {
+            put("S", new PDFName("Sect"));
+        } else if ("marker".equals(fo)) {
+            put("S", new PDFName("Private"));
+        }  else {
+            log.error("Accessibility: PDFStructElem constructor is missing: " + fo);
+        }
+        setParent(parent);
+        if (!"external-graphic".equals(fo) && !"instream-foreign-object".equals(fo)) {
+            put("K", new PDFArray());
+        }
+    }
+
+    /**
+     * This method is called for PDFStructElements which are direct children of
+     * fo:static-content or fo:flow-section
+     */
+    public void setLevel1() {
+        this.level1 = true;
+    }
+
+    /**
+     *
+     * @return true if the PDFStructElement is a direct child of
+     * fo:static-content or fo:flow-section
+     */
+    public boolean getLevel1() {
+        return this.level1;
+    }
+
+    /**
+     * Get the parent
+     * @return PDFStructElem of parent
+     */
+    public PDFObject getParentStructElem() {
+        return (PDFStructElem)this.parentObject;
+    }
+
+    /**
+     * Set the parent for this StructElem
+     * @param parent to be added
+     */
+    public void setParent(PDFObject parent) {
+        if (parent != null) {
+           put("P", new PDFReference(parent));
+        }
+    }
+
+    /**
+     * Get the source of this StructElem
+     * @return the source
+     */
+    public String getSource() {
+        return source;
+    }
+
+    /**
+     * The kids of this StructElem
+     * @return the kids
+     */
+    public PDFArray getKids() {
+        return (PDFArray)get("K");
+    }
+
+    /**
+     * Add a kid to this strucElem
+     * @param kid to be added
+     */
+    public void addKid(PDFObject kid) {
+        getKids().add(kid);
+    }
+
+    /**
+     * Add a kid, but only if it does not already exist
+     * @param kid to be added
+     * @return true if kid did not already exist
+     */
+    public boolean addUniqueKid(PDFObject kid) {
+        PDFArray mArray = getKids();
+        if (!mArray.contains(kid)) {
+            getKids().add(kid);
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * Add kid referenced through mcid integer
+     * used fo:external-graphic
+     * @param mcid of this kid
+     */
+    public void addMCIDKid(int mcid) {
+        put("K", mcid);
+    }
+
+    /**
+     * Add a page reference to this structElem
+     * @param pageObject to be added
+     */
+    public void addPage(Object pageObject) {
+        put("Pg", (PDFObject) pageObject);
+    }
+
+}
diff --git a/src/java/org/apache/fop/pdf/PDFStructTreeRoot.java b/src/java/org/apache/fop/pdf/PDFStructTreeRoot.java
new file mode 100644
index 000000000..e530b1582
--- /dev/null
+++ b/src/java/org/apache/fop/pdf/PDFStructTreeRoot.java
@@ -0,0 +1,67 @@
+/*
+ * 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.pdf;
+
+/**
+ * Class representing a PDF /StructTreeRoot dictionary.
+ */
+public class PDFStructTreeRoot extends PDFDictionary {
+
+    /**
+     * Create the /StructTreeRoot dictionary.
+     */
+    public PDFStructTreeRoot() {
+        super();
+        put("Type", new PDFName("StructTreeRoot"));
+        put("K", new PDFArray());
+    }
+
+    /**
+     * Add parentTree entry.
+     * @param parentTree to be added
+     */
+    public void addParentTree(PDFParentTree parentTree) {
+        put("ParentTree", parentTree);
+    }
+
+    /**
+     * Get the kids.
+     * @return the kids
+     */
+    public PDFArray getKids() {
+        return (PDFArray)get("K");
+    }
+
+    /**
+     * Returns the first child of the kids array (normally the structure tree root element)
+     * @return the first child
+     */
+    public PDFObject getFirstChild() {
+        return (PDFObject)getKids().get(0);
+    }
+
+    /**
+     * Adds a kid.
+     * @param kid to be added
+     */
+    public void addKid(PDFObject kid) {
+        getKids().add(kid);
+    }
+}
\ No newline at end of file
diff --git a/src/java/org/apache/fop/pdf/PDFTextUtil.java b/src/java/org/apache/fop/pdf/PDFTextUtil.java
index 6640f9b80..bb8816995 100644
--- a/src/java/org/apache/fop/pdf/PDFTextUtil.java
+++ b/src/java/org/apache/fop/pdf/PDFTextUtil.java
@@ -48,6 +48,7 @@ public abstract class PDFTextUtil {
     public static final int TR_CLIP = 7;
 
     private boolean inTextObject = false;
+    private boolean artifactMode = false;
     private String startText;
     private String endText;
     private boolean useMultiByte;
@@ -116,6 +117,15 @@ public abstract class PDFTextUtil {
     }
 
     /**
+     * Indicates whether we are in a text object and if that text object represents
+     * an artifact.
+     * @return true if in artifact-mode text object
+     */
+    public boolean inArtifactMode() {
+        return this.artifactMode;
+    }
+
+    /**
      * Called when a new text object should be started. Be sure to call setFont() before
      * issuing any text painting commands.
      */
@@ -128,11 +138,51 @@ public abstract class PDFTextUtil {
     }
 
     /**
+     * Begin of a regular text object, used for accessibility
+     * @param mcid of text object
+     * @param structElemType of parent
+     */
+    public void beginTextObjectAccess(int mcid, String structElemType) {
+        if (inTextObject) {
+            throw new IllegalStateException("Already in text object");
+        }
+           write(structElemType + " <</MCID "
+                   + String.valueOf(mcid) + ">>\nBDC\nBT\n");
+        this.inTextObject = true;
+    }
+
+    /**
+     * Begin of a text object marked as artifact (fo:leader in XSL-FO) text object.
+     * Used for accessibility.
+     */
+    public void beginArtifactTextObject() {
+        if (inTextObject) {
+            throw new IllegalStateException("Already in text object");
+        }
+        write("/Artifact\nBMC\nBT\n");
+        this.inTextObject = true;
+        this.artifactMode = true;
+    }
+
+    /**
      * Called when a text object should be ended.
      */
     public void endTextObject() {
+        endTextObject(false);
+    }
+
+    /**
+     * Called when a text object should be ended.
+     * @param accessEnabled indicating if accessibility is turned on or not
+     */
+    public void endTextObject(boolean accessEnabled) {
         checkInTextObject();
-        write("ET\n");
+        if (accessEnabled) {
+            write("ET\nEMC\n");
+        } else {
+            write("ET\n");
+        }
+        this.artifactMode = false;
         this.inTextObject = false;
         initValues();
     }