FOP-2596: NPE with changing ipd

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1736999 13f79535-47bb-0310-9956-ffa450edef68

fop-core/src/main/java/org/apache/fop/layoutmgr/AbstractBreaker.java

@@ -464,15 +464,7 @@ public abstract class AbstractBreaker {
         if (onLastPageAndIPDChanges && visitedBefore && this.originalRestartAtLM == null) {
             optimalBreak = null;
         }
-
-        int positionIndex = (optimalBreak != null) ? optimalBreak.position : start;
-        KnuthElement elementAtBreak = alg.getElement(positionIndex);
-        if (elementAtBreak.getPosition() == null) {
-            elementAtBreak = alg.getElement(0);
-        }
-        positionAtBreak = elementAtBreak.getPosition();
-        /* Retrieve the original position wrapped into this space position */
-        positionAtBreak = positionAtBreak.getPosition();
+        int positionIndex = findPositionIndex(optimalBreak, alg, start);
         if (ipdChangesOnNextPage || (positionAtBreak != null && positionAtBreak.getIndex() > -1)) {
             firstElementsForRestart = Collections.EMPTY_LIST;
             if (ipdChangesOnNextPage) {
@@ -542,6 +534,23 @@ public abstract class AbstractBreaker {
         return restartAtLM;
     }
 
+    private int findPositionIndex(KnuthNode optimalBreak, PageBreakingAlgorithm alg, int start) {
+        int positionIndex = (optimalBreak != null) ? optimalBreak.position : start;
+        for (int i = positionIndex; i < alg.par.size(); i++) {
+            KnuthElement elementAtBreak = alg.getElement(i);
+            if (elementAtBreak.getPosition() == null) {
+                elementAtBreak = alg.getElement(0);
+            }
+            positionAtBreak = elementAtBreak.getPosition();
+            /* Retrieve the original position wrapped into this space position */
+            positionAtBreak = positionAtBreak.getPosition();
+            if (positionAtBreak != null) {
+                return i;
+            }
+        }
+        return positionIndex;
+    }
+
     /**
      * Returns {@code true} if the given position or one of its descendants
      * corresponds to a non-restartable LM.

fop/test/layoutengine/standard-testcases/flow_changing-ipd_last-page_11.xml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  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.
+-->
+<!-- $Id$ -->
+<testcase>
+  <info>
+    <p>
+      This test checks that the definition of a special page-master for the last page with a
+      different width that the previous "rest" page causes FOP to redo the line breaking layout.
+    </p>
+  </info>
+  <fo>
+    <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format" xmlns:fox="http://xmlgraphics.apache.org/fop/extensions">
+      <fo:layout-master-set>
+        <fo:simple-page-master master-name="PageFront" page-width="8.5in" page-height="11in" margin-bottom="0in" margin-right="0in" margin-top="0in" margin-left="0in">
+          <fo:region-body margin-right="3.1in" margin-top="4.5in" margin-bottom="1in" margin-left="1in" region-name="letterPageBody"/>
+        </fo:simple-page-master>
+        <fo:simple-page-master master-name="PageRest" page-width="8.5in" page-height="11in" margin-bottom="0in" margin-right="0in" margin-top="0in" margin-left="0in">
+          <fo:region-body region-name="letterPageBody"/>
+        </fo:simple-page-master>
+        <fo:simple-page-master master-name="PageBlank" page-width="8.5in" page-height="11in" margin-bottom="0in" margin-right="0in" margin-top="0in" margin-left="0in">
+          <fo:region-body region-name="letterPageBodyBlank"/>
+        </fo:simple-page-master>
+        <fo:page-sequence-master master-name="LetterPages">
+          <fo:repeatable-page-master-alternatives>
+            <fo:conditional-page-master-reference blank-or-not-blank="not-blank" page-position="first" master-reference="PageFront"/>
+            <fo:conditional-page-master-reference blank-or-not-blank="not-blank" page-position="rest" master-reference="PageRest"/>
+            <fo:conditional-page-master-reference blank-or-not-blank="blank" page-position="rest" master-reference="PageBlank"/>
+          </fo:repeatable-page-master-alternatives>
+        </fo:page-sequence-master>
+      </fo:layout-master-set>
+      <fo:page-sequence format="1" id="th_default_sequence6" initial-page-number="auto" force-page-count="even" master-reference="LetterPages">
+        <fo:flow flow-name="letterPageBody">
+          <fo:block>
+            <fo:inline>
+              <fo:leader/>
+              test
+              <fo:block break-before="page"/>
+            </fo:inline>
+          </fo:block>
+        </fo:flow>
+      </fo:page-sequence>
+    </fo:root>
+  </fo>
+  <checks>
+    <eval expected="test" xpath="//pageViewport[1]//regionViewport[1]//word"/>
+  </checks>
+</testcase>