Bugzilla #46315: extension to disable column balancing before blocks spanning the whole page, in multiple-column documents.

Patch submitted by Georg Datterl, applied with some modifications (mainly Checkstyle issues)


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@738514 13f79535-47bb-0310-9956-ffa450edef68

8 files changed, 71 insertions, 9 deletions

diff --git a/src/java/org/apache/fop/fo/Constants.java b/src/java/org/apache/fop/fo/Constants.java
index 91ff780bd..a1ccb20e7 100644
--- a/src/java/org/apache/fop/fo/Constants.java
+++ b/src/java/org/apache/fop/fo/Constants.java
@@ -766,8 +766,13 @@ public interface Constants {
     int PR_X_WIDOW_CONTENT_LIMIT = 271;
     /** Property constant - FOP proprietary: limit for orphan content in lists and tables */
     int PR_X_ORPHAN_CONTENT_LIMIT = 272;
+    /**
+     * Property constant - FOP proprietary: disable balancing of columns in
+     * multi-column layouts.
+     */
+    int PR_X_DISABLE_COLUMN_BALANCING = 273;
     /** Number of property constants defined */
-    int PROPERTY_COUNT = 272;
+    int PROPERTY_COUNT = 273;
 
     // compound property constants
 
diff --git a/src/java/org/apache/fop/fo/FOPropertyMapping.java b/src/java/org/apache/fop/fo/FOPropertyMapping.java
index e890b9e24..b4a864e43 100644
--- a/src/java/org/apache/fop/fo/FOPropertyMapping.java
+++ b/src/java/org/apache/fop/fo/FOPropertyMapping.java
@@ -1895,6 +1895,13 @@ public final class FOPropertyMapping implements Constants {
         m.addEnum("all", getEnumProperty(EN_ALL, "ALL"));
         m.setDefault("none");
         addPropertyMaker("span", m);
+
+        // fox:disable-column-balancing
+        m  = new EnumProperty.Maker(PR_X_DISABLE_COLUMN_BALANCING);
+        m.useGeneric(genericBoolean);
+        m.setInherited(true);
+        m.setDefault("false");
+        addPropertyMaker("fox:disable-column-balancing", m);
     }
 
     private void createLeaderAndRuleProperties() {
diff --git a/src/java/org/apache/fop/fo/extensions/ExtensionElementMapping.java b/src/java/org/apache/fop/fo/extensions/ExtensionElementMapping.java
index 56521b7e8..927bed0f7 100644
--- a/src/java/org/apache/fop/fo/extensions/ExtensionElementMapping.java
+++ b/src/java/org/apache/fop/fo/extensions/ExtensionElementMapping.java
@@ -45,6 +45,7 @@ public class ExtensionElementMapping extends ElementMapping {
         propertyAttributes.add("widow-content-limit");
         propertyAttributes.add("orphan-content-limit");
         propertyAttributes.add("internal-destination");
+        propertyAttributes.add("disable-column-balancing");
     }
 
     /**
diff --git a/src/java/org/apache/fop/fo/flow/Block.java b/src/java/org/apache/fop/fo/flow/Block.java
index 4645734b2..daaebd6d0 100644
--- a/src/java/org/apache/fop/fo/flow/Block.java
+++ b/src/java/org/apache/fop/fo/flow/Block.java
@@ -21,8 +21,6 @@ package org.apache.fop.fo.flow;
 
 import java.awt.Color;
 
-import org.xml.sax.Locator;
-
 import org.apache.fop.apps.FOPException;
 import org.apache.fop.datatypes.Length;
 import org.apache.fop.datatypes.Numeric;
@@ -40,6 +38,7 @@ import org.apache.fop.fo.properties.CommonMarginBlock;
 import org.apache.fop.fo.properties.CommonRelativePosition;
 import org.apache.fop.fo.properties.KeepProperty;
 import org.apache.fop.fo.properties.SpaceProperty;
+import org.xml.sax.Locator;
 
  /**
   * Class modelling the <a href="http://www.w3.org/TR/xsl/#fo_block">
@@ -80,6 +79,7 @@ public class Block extends FObjMixed implements BreakPropertySet {
     private int whiteSpaceCollapse;
     private Numeric widows;
     private int wrapOption;
+    private int disableColumnBalancing;
     // Unused but valid items, commented out for performance:
     //     private CommonAccessibility commonAccessibility;
     //     private CommonAural commonAural;
@@ -130,6 +130,7 @@ public class Block extends FObjMixed implements BreakPropertySet {
         whiteSpaceCollapse = pList.get(PR_WHITE_SPACE_COLLAPSE).getEnum();
         widows = pList.get(PR_WIDOWS).getNumeric();
         wrapOption = pList.get(PR_WRAP_OPTION).getEnum();
+        disableColumnBalancing = pList.get(PR_X_DISABLE_COLUMN_BALANCING).getEnum();
     }
 
     /** {@inheritDoc} */
@@ -318,6 +319,15 @@ public class Block extends FObjMixed implements BreakPropertySet {
         return this.lineHeightShiftAdjustment;
     }
 
+     /**
+     * @return the "fox:disable-column-balancing" property, one of
+     * {@link Constants#EN_TRUE}, {@link Constants#EN_FALSE}
+     */
+     public int getDisableColumnBalancing() {
+         return disableColumnBalancing;
+     }
+
+
     /** {@inheritDoc} */
     public CharIterator charIterator() {
         return NullCharIterator.getInstance();
diff --git a/src/java/org/apache/fop/fo/flow/BlockContainer.java b/src/java/org/apache/fop/fo/flow/BlockContainer.java
index b0bfb3a32..2a8d73002 100644
--- a/src/java/org/apache/fop/fo/flow/BlockContainer.java
+++ b/src/java/org/apache/fop/fo/flow/BlockContainer.java
@@ -19,10 +19,7 @@
 
 package org.apache.fop.fo.flow;
 
-import org.xml.sax.Locator;
-
 import org.apache.fop.apps.FOPException;
-import org.apache.fop.datatypes.Length;
 import org.apache.fop.datatypes.Numeric;
 import org.apache.fop.fo.FONode;
 import org.apache.fop.fo.FObj;
@@ -34,6 +31,7 @@ import org.apache.fop.fo.properties.CommonBorderPaddingBackground;
 import org.apache.fop.fo.properties.CommonMarginBlock;
 import org.apache.fop.fo.properties.KeepProperty;
 import org.apache.fop.fo.properties.LengthRangeProperty;
+import org.xml.sax.Locator;
 
 /**
  * Class modelling the <a href="http://www.w3.org/TR/xsl/#fo_block-container">
@@ -56,6 +54,7 @@ public class BlockContainer extends FObj implements BreakPropertySet {
     private int overflow;
     private Numeric referenceOrientation;
     private int span;
+    private int disableColumnBalancing;
     private int writingMode;
     // Unused but valid items, commented out for performance:
     //     private int intrusionDisplace;
@@ -94,6 +93,7 @@ public class BlockContainer extends FObj implements BreakPropertySet {
         referenceOrientation = pList.get(PR_REFERENCE_ORIENTATION).getNumeric();
         span = pList.get(PR_SPAN).getEnum();
         writingMode = pList.get(PR_WRITING_MODE).getEnum();
+        disableColumnBalancing = pList.get(PR_X_DISABLE_COLUMN_BALANCING).getEnum();
     }
 
     /** {@inheritDoc} */
@@ -217,6 +217,15 @@ public class BlockContainer extends FObj implements BreakPropertySet {
         return this.span;
     }
 
+    /**
+     * @return the "fox:disable-column-balancing" property, one of
+     * {@link Constants#EN_TRUE}, {@link Constants#EN_FALSE}
+     */
+    public int getDisableColumnBalancing() {
+        return disableColumnBalancing;
+    }
+
+
     /** @return the "writing-mode" property */
     public int getWritingMode() {
         return writingMode;
diff --git a/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java b/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
index 42f08a42d..245fa7235 100644
--- a/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
+++ b/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
@@ -25,7 +25,6 @@ import java.util.ListIterator;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.apache.fop.area.Area;
 import org.apache.fop.area.BlockParent;
 import org.apache.fop.fo.pagination.Flow;
@@ -82,14 +81,22 @@ public class FlowLayoutManager extends BlockStackingLayoutManager
             }
 
             int span = EN_NONE;
+            int disableColumnBalancing = EN_FALSE;
             if (curLM instanceof BlockLayoutManager) {
                 span = ((BlockLayoutManager)curLM).getBlockFO().getSpan();
+                disableColumnBalancing = ((BlockLayoutManager) curLM).getBlockFO()
+                        .getDisableColumnBalancing();
             } else if (curLM instanceof BlockContainerLayoutManager) {
                 span = ((BlockContainerLayoutManager)curLM).getBlockContainerFO().getSpan();
+                disableColumnBalancing = ((BlockContainerLayoutManager) curLM)
+                        .getBlockContainerFO().getDisableColumnBalancing();
             }
 
             int currentSpan = context.getCurrentSpan();
             if (currentSpan != span) {
+                if (span == EN_ALL) {
+                    context.setDisableColumnBalancing(disableColumnBalancing);
+                }
                 log.debug("span change from " + currentSpan + " to " + span);
                 context.signalSpanChange(span);
                 SpaceResolver.resolveElementList(returnList);
diff --git a/src/java/org/apache/fop/layoutmgr/LayoutContext.java b/src/java/org/apache/fop/layoutmgr/LayoutContext.java
index 3526ed239..4d56d1657 100644
--- a/src/java/org/apache/fop/layoutmgr/LayoutContext.java
+++ b/src/java/org/apache/fop/layoutmgr/LayoutContext.java
@@ -148,6 +148,8 @@ public class LayoutContext {
     private int pendingKeepWithNext = BlockLevelLayoutManager.KEEP_AUTO;
     private int pendingKeepWithPrevious = BlockLevelLayoutManager.KEEP_AUTO;
 
+    private int disableColumnBalancing;
+
     /**
      * Copy constructor for creating child layout contexts.
      * @param parentLC the parent layout context to copy from
@@ -170,6 +172,7 @@ public class LayoutContext {
         this.pendingKeepWithNext = parentLC.pendingKeepWithNext;
         this.pendingKeepWithPrevious = parentLC.pendingKeepWithPrevious;
         // Copy other fields as necessary.
+        this.disableColumnBalancing = parentLC.disableColumnBalancing;
     }
 
     /**
@@ -412,7 +415,7 @@ public class LayoutContext {
 
     /**
      * Sets (Copies) the stack limits in both directions from another layout context.
-     * @param context the layout context to taje the values from
+     * @param context the layout context to take the values from
      */
     public void setStackLimitsFrom(LayoutContext context) {
         setStackLimitBP(context.getStackLimitBP());
@@ -681,5 +684,23 @@ public class LayoutContext {
         + (breakAfter != Constants.EN_AUTO ? "break-after" : "") + "]";
     }
 
+    /**
+     * Returns whether the column balancer should be disabled before a spanning block
+     *
+     * @return one of {@link Constants#EN_TRUE}, {@link Constants#EN_FALSE}
+     */
+    public int getDisableColumnBalancing() {
+        return disableColumnBalancing;
+    }
+
+    /**
+     * Sets whether the column balancer should be disabled before a spanning block
+     *
+     * @param disableColumnBalancing the value of the fox:disable-column-balancing property
+     * @see #getDisableColumnBalancing()
+     */
+    public void setDisableColumnBalancing(int disableColumnBalancing) {
+        this.disableColumnBalancing = disableColumnBalancing;
+    }
 }
 
diff --git a/src/java/org/apache/fop/layoutmgr/PageBreaker.java b/src/java/org/apache/fop/layoutmgr/PageBreaker.java
index 9ff520804..5dc1576c7 100644
--- a/src/java/org/apache/fop/layoutmgr/PageBreaker.java
+++ b/src/java/org/apache/fop/layoutmgr/PageBreaker.java
@@ -108,7 +108,9 @@ public class PageBreaker extends AbstractBreaker {
         if (childLC.getNextSpan() != Constants.NOT_SET) {
             //Next block list will have a different span.
             nextSequenceStartsOn = childLC.getNextSpan();
-            needColumnBalancing = (childLC.getNextSpan() == Constants.EN_ALL);
+            needColumnBalancing = childLC.getNextSpan() == Constants.EN_ALL
+                    && childLC.getDisableColumnBalancing() == Constants.EN_FALSE;
+
         }
         if (needColumnBalancing) {
             AbstractBreaker.log.debug(