Handle middle-of-the-page case without using a glue.

Using a glue may cause a spurious empty page if the multi-switch is at the end of the flow, with no satisfying way of fixing that.
Patch by Seifeddine Dridi


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_WhitespaceManagement@1582469 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/fop/layoutmgr/BestFitLayoutUtils.java

@@ -40,10 +40,12 @@ public final class BestFitLayoutUtils {
 
         public List<Position> getPositionList() {
             List<Position> positions = new LinkedList<Position>();
-            if (knuthList != null) {
+            if (knuthList != null && !knuthList.isEmpty()) {
                 SpaceResolver.performConditionalsNotification(knuthList, 0, knuthList.size() - 1, -1);
-                for (ListElement elem : knuthList) {
-                    positions.add(elem.getPosition());
+                for (ListElement el : knuthList) {
+                    if (el.getPosition() != null) {
+                        positions.add(el.getPosition());
+                    }
                 }
             }
             return positions;
@@ -75,10 +77,6 @@ public final class BestFitLayoutUtils {
         // when they are at the end of the Knuth list.
         knuthList.add(new KnuthBox(0, new Position(lm), false));
         knuthList.add(bestFitPenalty);
-        Variant firstVariant = bestFitPenalty.getVariants().get(0);
-        BestFitPosition pos = new BestFitPosition(lm);
-        pos.setKnuthList(firstVariant.knuthList);
-        knuthList.add(new KnuthGlue(firstVariant.width, 0, 0, pos, false));
         knuthList.add(new KnuthBox(0, new Position(lm), false));
         return knuthList;
     }

src/java/org/apache/fop/layoutmgr/BestFitPenalty.java

@@ -35,10 +35,12 @@ public class BestFitPenalty extends KnuthPenalty {
 
         public final List<ListElement> knuthList;
         public final int width;
+        public int penaltyIndex;
 
         public Variant(List<ListElement> knuthList, int width) {
             this.knuthList = knuthList;
             this.width = width;
+            this.penaltyIndex = -1;
         }
 
         public KnuthElement toPenalty() {

src/java/org/apache/fop/layoutmgr/MultiCaseLayoutManager.java

@@ -18,14 +18,10 @@
 package org.apache.fop.layoutmgr;
 
 import org.apache.fop.area.Area;
-import org.apache.fop.area.Block;
-import org.apache.fop.area.LineArea;
 import org.apache.fop.fo.FObj;
 
 public class MultiCaseLayoutManager extends BlockStackingLayoutManager {
 
-    private Block curBlockArea;
-
     public MultiCaseLayoutManager(FObj node) {
         super(node);
     }
@@ -47,36 +43,12 @@ public class MultiCaseLayoutManager extends BlockStackingLayoutManager {
 
     @Override
     public Area getParentArea(Area childArea) {
-        if (curBlockArea == null) {
-            curBlockArea = new Block();
-            curBlockArea.setIPD(super.getContentAreaIPD());
-            // Set up dimensions
-            // Must get dimensions from parent area
-            /*Area parentArea = */parentLayoutManager.getParentArea(curBlockArea);
-            setCurrentArea(curBlockArea);
-        }
-        return curBlockArea;
+        return parentLayoutManager.getParentArea(childArea);
     }
 
     @Override
     public void addChildArea(Area childArea) {
-        if (curBlockArea != null) {
-            if (childArea instanceof LineArea) {
-                curBlockArea.addLineArea((LineArea) childArea);
-            } else {
-                curBlockArea.addBlock((Block) childArea);
-            }
-        }
-    }
-
-    /**
-     * Force current area to be added to parent area.
-     */
-    @Override
-    protected void flush() {
-        if (getCurrentArea() != null) {
-            super.flush();
-        }
+        parentLayoutManager.addChildArea(childArea);
     }
 
     /** {@inheritDoc} */

src/java/org/apache/fop/layoutmgr/MultiSwitchLayoutManager.java

@@ -22,14 +22,10 @@ import java.util.LinkedList;
 import java.util.List;
 
 import org.apache.fop.area.Area;
-import org.apache.fop.area.Block;
-import org.apache.fop.area.LineArea;
 import org.apache.fop.fo.FObj;
 
 public class MultiSwitchLayoutManager extends BlockStackingLayoutManager {
 
-    private Block curBlockArea;
-
     public MultiSwitchLayoutManager(FObj node) {
         super(node);
     }
@@ -55,61 +51,14 @@ public class MultiSwitchLayoutManager extends BlockStackingLayoutManager {
         return BestFitLayoutUtils.getKnuthList(this, childrenLists);
     }
 
-    @Override
-    public Keep getKeepTogether() {
-        return Keep.KEEP_AUTO;
-    }
-
-    @Override
-    public Keep getKeepWithNext() {
-        return Keep.KEEP_AUTO;
-    }
-
-    @Override
-    public Keep getKeepWithPrevious() {
-        return Keep.KEEP_AUTO;
-    }
-
-    @Override
-    public int getContentAreaIPD() {
-        if (curBlockArea != null) {
-            return curBlockArea.getIPD();
-        }
-        return super.getContentAreaIPD();
-    }
-
     @Override
     public Area getParentArea(Area childArea) {
-        if (curBlockArea == null) {
-            curBlockArea = new Block();
-            curBlockArea.setIPD(super.getContentAreaIPD());
-            setCurrentArea(curBlockArea);
-            // Set up dimensions
-            // Must get dimensions from parent area
-            /*Area parentArea = */parentLayoutManager.getParentArea(curBlockArea);
-        }
-        return curBlockArea;
+        return parentLayoutManager.getParentArea(childArea);
     }
 
     @Override
     public void addChildArea(Area childArea) {
-        if (curBlockArea != null) {
-            if (childArea instanceof LineArea) {
-                curBlockArea.addLineArea((LineArea) childArea);
-            } else {
-                curBlockArea.addBlock((Block) childArea);
-            }
-        }
-    }
-
-    /**
-     * Force current area to be added to parent area.
-     */
-    @Override
-    protected void flush() {
-        if (curBlockArea != null) {
-            parentLayoutManager.addChildArea(getCurrentArea());
-        }
+        parentLayoutManager.addChildArea(childArea);
     }
 
     @Override
@@ -121,9 +70,6 @@ public class MultiSwitchLayoutManager extends BlockStackingLayoutManager {
 
         AreaAdditionUtil.addAreas(this, newPosIter, context);
         flush();
-        // TODO removing the following line forces the generated area
-        // to be rendered twice in some cases...
-        curBlockArea = null;
     }
 
 }

src/java/org/apache/fop/layoutmgr/PageBreakingAlgorithm.java

@@ -99,9 +99,6 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
     private int currentKeepContext = Constants.EN_AUTO;
     private KnuthNode lastBeforeKeepContextSwitch;
 
-    /** Holds the variant of a dynamic content that must be attached to the next page node */
-    private Variant variant;
-
     /**
      * Construct a page breaking algorithm.
      * @param topLevelLM the top level layout manager
@@ -156,7 +153,10 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
         /** Index of the last inserted element of the last inserted footnote. */
         public int footnoteElementIndex;
 
+        /** Current active variant attached to this node */
         public final Variant variant;
+        /** Pending variant to be assigned to all descending nodes */
+        public Variant pendingVariant;
 
         public KnuthPageNode(int position,
                              int line, int fitness,
@@ -201,7 +201,7 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
             bestTotalFootnotesLength[fitness] = totalFootnotesLength;
             bestFootnoteListIndex[fitness] = footnoteListIndex;
             bestFootnoteElementIndex[fitness] = footnoteElementIndex;
-            bestVariant[fitness] = variant;
+            bestVariant[fitness] = ((KnuthPageNode) node).pendingVariant;
         }
 
         public int getInsertedFootnotesLength(int fitness) {
@@ -223,6 +223,7 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
         public Variant getVariant(int fitness) {
             return bestVariant[fitness];
         }
+
     }
 
     /** {@inheritDoc} */
@@ -315,7 +316,8 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
                                  insertedFootnotesLength, totalFootnotesLength,
                                  footnoteListIndex, footnoteElementIndex,
                                  adjustRatio, availableShrink, availableStretch,
-                                 difference, totalDemerits, previous, variant);
+                                 difference, totalDemerits, previous,
+                                 (previous != null) ? ((KnuthPageNode)previous).pendingVariant : null);
     }
 
     /** {@inheritDoc} */
@@ -525,12 +527,14 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
         int actualWidth = totalWidth - pageNode.totalWidth;
         int footnoteSplit;
         boolean canDeferOldFN;
-        variant = null;
         if (element.isPenalty()) {
             if (element instanceof BestFitPenalty) {
-                actualWidth += handleBestFitPenalty(activeNode, (BestFitPenalty) element, elementIndex);
+                actualWidth += handleBestFitPenalty(pageNode, (BestFitPenalty) element, elementIndex);
             } else {
                 actualWidth += element.getWidth();
+                if (pageNode.pendingVariant != null) {
+                    actualWidth += ((KnuthPageNode) activeNode).pendingVariant.width;
+                }
             }
         }
         if (footnotesPending) {
@@ -591,13 +595,14 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
         }
     }
 
-    private int handleBestFitPenalty(KnuthNode activeNode, BestFitPenalty penalty, int elementIndex) {
+    private int handleBestFitPenalty(KnuthPageNode activeNode, BestFitPenalty penalty, int elementIndex) {
         for (Variant var : penalty.getVariants()) {
             int difference = computeDifference(activeNode, var.toPenalty(), elementIndex);
             double r = computeAdjustmentRatio(activeNode, difference);
             if (r >= -1.0) {
-                variant = var;
-                return variant.width;
+                var.penaltyIndex = elementIndex;
+                activeNode.pendingVariant = var;
+                return var.width;
             }
         }
         return 0;
@@ -1018,7 +1023,7 @@ class PageBreakingAlgorithm extends BreakingAlgorithm {
         // Check if the given node has an attached variant of a dynamic content
         KnuthPageNode pageNode = (KnuthPageNode) bestActiveNode;
         if (pageNode.variant != null) {
-            BestFitPenalty penalty = (BestFitPenalty) par.get(pageNode.position);
+            BestFitPenalty penalty = (BestFitPenalty) par.get(pageNode.variant.penaltyIndex);
             penalty.setActiveVariant(pageNode.variant);
         }
         int difference = bestActiveNode.difference;

test/layoutengine/standard-testcases/multi-switch_best-fit_multiple-variants.xml

@@ -106,13 +106,13 @@
     <!-- 1. First variant -->
     <eval expected="3"                        xpath="count(//pageSequence[1]/pageViewport)"/>
     <eval expected="Filler"                         xpath="//pageSequence[1]/pageViewport[2]//flow/block[1]"/>
-    <eval expected="Variant 1 line 1"               xpath="//pageSequence[1]/pageViewport[2]//flow/block[3]/block/block[1]"/>
+    <eval expected="Variant 1 line 1"               xpath="//pageSequence[1]/pageViewport[2]//flow/block[3]"/>
     <eval expected="This text should be on page 3." xpath="//pageSequence[1]/pageViewport[3]//flow/block[1]"/>
 
     <!-- 2. Second variant -->
     <eval expected="3"                        xpath="count(//pageSequence[2]/pageViewport)"/>
     <eval expected="Page 2 line 1"                  xpath="//pageSequence[2]/pageViewport[2]//flow/block[1]"/>
-    <eval expected="Variant 2 line 1"               xpath="//pageSequence[2]/pageViewport[2]//flow/block[4]/block/block[1]"/>
+    <eval expected="Variant 2 line 1"               xpath="//pageSequence[2]/pageViewport[2]//flow/block[4]"/>
     <eval expected="This text should be on page 3." xpath="//pageSequence[2]/pageViewport[3]//flow/block[1]"/>
 
     <!-- 3. No variant -->
@@ -122,8 +122,9 @@
     <eval expected="Page 2 line 2"                  xpath="//pageSequence[3]/pageViewport[2]//flow/block[2]"/>
     <eval expected="Filler"                         xpath="//pageSequence[3]/pageViewport[2]//flow/block[3]"/>
     <eval expected="Before the multi-switch"        xpath="//pageSequence[3]/pageViewport[2]//flow/block[4]"/>
-    <eval expected="2"                        xpath="count(//pageSequence[3]/pageViewport[3]//flow/block)"/>
-    <eval expected="Variant 1 line 1"               xpath="//pageSequence[3]/pageViewport[3]//flow/block[1]/block/block[1]"/>
-    <eval expected="This text should be on page 3." xpath="//pageSequence[3]/pageViewport[3]//flow/block[2]"/>
+    <eval expected="3"                        xpath="count(//pageSequence[3]/pageViewport[3]//flow/block)"/>
+    <eval expected="Variant 1 line 1"               xpath="//pageSequence[3]/pageViewport[3]//flow/block[1]"/>
+    <eval expected="Variant 1 line 2" xpath="//pageSequence[3]/pageViewport[3]//flow/block[2]"/>
+    <eval expected="This text should be on page 3." xpath="//pageSequence[3]/pageViewport[3]//flow/block[3]"/>
   </checks>
 </testcase>