From 8c3ee10b15c1aae9c4157fab047672583911f6ed Mon Sep 17 00:00:00 2001
From: Jeremias Maerki <jeremias@apache.org>
Date: Wed, 29 Jun 2005 12:59:31 +0000
Subject: [PATCH] Span change detection and infastructure for signalling it.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@202364 13f79535-47bb-0310-9956-ffa450edef68
---
 .../fop/layoutmgr/FlowLayoutManager.java      | 22 +++++++++------
 .../apache/fop/layoutmgr/LayoutContext.java   | 28 +++++++++++++++++--
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java b/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
index 9408d03e8..89015813d 100644
--- a/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
+++ b/src/java/org/apache/fop/layoutmgr/FlowLayoutManager.java
@@ -41,11 +41,7 @@ public class FlowLayoutManager extends BlockStackingLayoutManager
     /** Array of areas currently being filled stored by area class */
     private BlockParent[] currentAreas = new BlockParent[Area.CLASS_MAX];
 
-    /**
-     * Used to count the number of subsequent times to layout child areas on
-     * multiple pages.
-     */
-    private int numSubsequentOverflows = 0;
+    private int currentSpan = EN_NONE;
     
     /**
      * This is the top level layout manager.
@@ -72,8 +68,6 @@ public class FlowLayoutManager extends BlockStackingLayoutManager
 
         // currently active LM
         BlockLevelLayoutManager curLM;
-        BlockLevelLayoutManager prevLM = null;
-        //MinOptMax stackSize = new MinOptMax();
         LinkedList returnedList;
         LinkedList returnList = new LinkedList();
 
@@ -84,6 +78,19 @@ public class FlowLayoutManager extends BlockStackingLayoutManager
                 continue;
             }
 
+            int span = EN_NONE;
+            if (curLM instanceof BlockLayoutManager) {
+                span = ((BlockLayoutManager)curLM).getBlockFO().getSpan();
+            } else if (curLM instanceof BlockContainerLayoutManager) {
+                span = ((BlockContainerLayoutManager)curLM).getBlockContainerFO().getSpan();
+            }
+            if (currentSpan != span) {
+                log.debug("span change from " + currentSpan + " to " + span);
+                context.signalSpanChange(span);
+                currentSpan = span;
+                return returnList;
+            }
+            
             // Set up a LayoutContext
             //MinOptMax bpd = context.getStackLimit();
 
@@ -142,7 +149,6 @@ public class FlowLayoutManager extends BlockStackingLayoutManager
                 childLC.setFlags(LayoutContext.KEEP_WITH_NEXT_PENDING, false);
                 context.setFlags(LayoutContext.KEEP_WITH_NEXT_PENDING);
             }
-            prevLM = curLM;
         }
 
         setFinished(true);
diff --git a/src/java/org/apache/fop/layoutmgr/LayoutContext.java b/src/java/org/apache/fop/layoutmgr/LayoutContext.java
index cc468fec5..3703502b0 100644
--- a/src/java/org/apache/fop/layoutmgr/LayoutContext.java
+++ b/src/java/org/apache/fop/layoutmgr/LayoutContext.java
@@ -18,6 +18,7 @@
 
 package org.apache.fop.layoutmgr;
 
+import org.apache.fop.fo.Constants;
 import org.apache.fop.traits.MinOptMax;
 
 
@@ -74,8 +75,8 @@ public class LayoutContext {
      */
     MinOptMax stackLimit;
 
-    /** True if current top-level reference area is spanning. */
-    boolean bIsSpan;
+    /** True if current element list is spanning in multi-column layout. */
+    private int nextSpan = Constants.NOT_SET;
 
     /** inline-progression-dimension of nearest ancestor reference area */
     int refIPD;
@@ -294,6 +295,29 @@ public class LayoutContext {
         iSpaceAfter = sp;
     }
     
+    /**
+     * @return true if the current element list ends early because of a span change
+     * in multi-column layout.
+     */
+    public int getNextSpan() {
+        return nextSpan;
+    }
+    
+    /**
+     * Used to signal the PSLM that the element list ends early because of a span change in
+     * multi-column layout.
+     * @param span the new span value (legal values: NOT_SET, EN_NONE, EN_ALL)
+     */
+    public void signalSpanChange(int span) {
+        if (span == Constants.NOT_SET || span == Constants.EN_NONE || span == Constants.EN_ALL) {
+            this.nextSpan = span;
+        } else {
+            throw new IllegalArgumentException("Illegal value on signalSpanChange() for span: "
+                    + span);
+        }
+    }
+    
+    /** @see java.lang.Object#toString() */
     public String toString() {
         return "Layout Context:" +
         "\nStack Limit: \t" + (getStackLimit() == null ? "null" : getStackLimit().toString()) +
-- 
2.39.5