Subject: [PATCH 11/20] Add support for clearing objects at write time

---
 src/java/org/apache/fop/pdf/PDFClearable.java |   34 ++++++++++++++++
 src/java/org/apache/fop/pdf/PDFDocument.java  |   51 ++++++++++++++++++++++++-
 2 files changed, 84 insertions(+), 1 deletions(-)
 create mode 100644 src/java/org/apache/fop/pdf/PDFClearable.java

diff --git a/src/java/org/apache/fop/pdf/PDFClearable.java b/src/java/org/apache/fop/pdf/PDFClearable.java
new file mode 100644
index 0000000..e525c65
--- /dev/null
+++ b/src/java/org/apache/fop/pdf/PDFClearable.java
@@ -0,0 +1,34 @@
+/*
+ * 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: PDFWritable.java 679326 2008-07-24 09:35:34Z vhennebert $ */
+
+package org.apache.fop.pdf;
+
+/**
+ * This interface is implemented by classes that can be serialized to a PDF file either by
+ * serializing the object or by writing a indirect reference to the actual object.
+ * The object supports clearing the content after writing.
+ */
+public interface PDFClearable extends PDFWritable {
+
+    /**
+     * Clear object content
+     */
+    void clear();
+
+}
diff --git a/src/java/org/apache/fop/pdf/PDFDocument.java b/src/java/org/apache/fop/pdf/PDFDocument.java
index 1890669..e97e649 100644
--- a/src/java/org/apache/fop/pdf/PDFDocument.java
+++ b/src/java/org/apache/fop/pdf/PDFDocument.java
@@ -98,6 +98,9 @@ public class PDFDocument {
     /** the objects themselves */
     private List objects = new LinkedList();
 
+    /** the objects themselves (to be cleared after writing) */
+    private List clearobjects = new LinkedList();
+
     /** Indicates what PDF version is active */
     private int pdfVersion = PDF_VERSION_1_4;
 
@@ -378,6 +381,20 @@ public class PDFDocument {
     }
 
     /**
+     * Registers a {@link PDFObject} in this PDF document.
+     * The object is assigned a new object number.
+     *
+     * @param obj {@link PDFObject} to add
+     * @param clear object after writing
+     * @return the added {@link PDFObject} added (with its object number set)
+     */
+    public PDFObject registerObject(PDFObject obj, boolean clear) {
+        assignObjectNumber(obj);
+        addObject(obj, clear);
+        return obj;
+    }
+
+    /**
      * Assigns the {@link PDFObject} an object number,
      * and sets the parent of the {@link PDFObject} to this document.
      *
@@ -413,6 +430,17 @@ public class PDFDocument {
      * @param obj {@link PDFObject} to add
      */
     public void addObject(PDFObject obj) {
+        addObject(obj, false);
+    }
+
+    /**
+     * Adds a {@link PDFObject} to this document.
+     * The object <em>MUST</em> have an object number assigned.
+     *
+     * @param obj {@link PDFObject} to add
+     * @param clear Clear object after writing (if possible)
+     */
+    public void addObject(PDFObject obj, boolean clear) {
         if (obj == null) {
             throw new NullPointerException("obj must not be null");
         }
@@ -423,7 +451,10 @@ public class PDFDocument {
         }
 
         //Add object to list
-        this.objects.add(obj);
+        if (clear)
+            this.clearobjects.add(obj);
+        else
+            this.objects.add(obj);
 
         //Add object to special lists where necessary
         if (obj instanceof PDFFunction) {
@@ -927,6 +958,24 @@ public class PDFDocument {
             this.position += object.output(stream);
         }
 
+        while (this.clearobjects.size() > 0) {
+            /* Retrieve first */
+            PDFObject object = (PDFObject)this.clearobjects.remove(0);
+            /*
+             * add the position of this object to the list of object
+             * locations
+             */
+            setLocation(object.getObjectNumber() - 1, this.position);
+
+            /*
+             * output the object and increment the character position
+             * by the object's length
+             */
+            this.position += object.output(stream);
+            if (object instanceof PDFClearable)
+                ((PDFClearable)object).clear();
+        }
+
         //Clear all objects written to the file
         //this.objects.clear();
     }
-- 
1.6.4.2