Looks like the 2-column situation has to be handled differently than the 3-column...

The 4-column example shows that my current approach is not good enough and needs to be revisited.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@355063 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/src/java/org/apache/fop/layoutmgr/BalancingColumnBreakingAlgorithm.java b/src/java/org/apache/fop/layoutmgr/BalancingColumnBreakingAlgorithm.java
index b3a887f34d79958ca841815a89964c808324ddfe..77c8b43c4e87e5ca288090b97dc27ed1cef5a31a 100644 (file)
--- a/src/java/org/apache/fop/layoutmgr/BalancingColumnBreakingAlgorithm.java
+++ b/src/java/org/apache/fop/layoutmgr/BalancingColumnBreakingAlgorithm.java
@@ -76,12 +76,18 @@ public class BalancingColumnBreakingAlgorithm extends PageBreakingAlgorithm {
             log.trace("balance=" + balance);\r
         }\r
         double absBalance = Math.abs(balance);\r
+        dem = absBalance;\r
         //Step 1: This does the rough balancing\r
-        if (balance <= 0) {\r
-            dem = absBalance;\r
+        if (columnCount > 2) {\r
+            if (balance > 0) {\r
+                //shorter parts are less desired than longer ones\r
+                dem = dem * 1.2f;\r
+            }\r
         } else {\r
-            //shorter parts are less desired than longer ones\r
-            dem = absBalance * 1.2f;\r
+            if (balance < 0) {\r
+                //shorter parts are less desired than longer ones\r
+                dem = dem * 1.2f;\r
+            }\r
         }\r
         //Step 2: This helps keep the trailing parts shorter than the previous ones \r
         dem += (avgRestLen) / 1000f;\r

diff --git a/test/layoutengine/disabled-testcases.xml b/test/layoutengine/disabled-testcases.xml
index a4b3d64e68543f59b4484deb9d356b4d1259018e..0fe5c0c1430c365de02b88aa9f06407922afdb35 100755 (executable)
--- a/test/layoutengine/disabled-testcases.xml
+++ b/test/layoutengine/disabled-testcases.xml
@@ -232,6 +232,12 @@
     <description>Footnotes may overlap with text of the region-body in
     multi-column documents.</description>
   </testcase>
+  <testcase>
+    <name>Column Balancing problems</name>
+    <file>region-body_column-count_balance_4col.xml</file>
+    <description>Situation in a 4-column document where the column balancing doesn't work and even causes some
+    content to disappear.</description>
+  </testcase>
   <testcase>
     <name>No background-images on table-body</name>
     <file>table-body_background-image.xml</file>

diff --git a/test/layoutengine/standard-testcases/region-body_column-count_balance_2col.xml b/test/layoutengine/standard-testcases/region-body_column-count_balance_2col.xml
new file mode 100644 (file)
index 0000000..aacb350
--- /dev/null
+++ b/test/layoutengine/standard-testcases/region-body_column-count_balance_2col.xml
@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Copyright 2005 The Apache Software Foundation
+
+  Licensed 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 multi-column documents. Checks column balancing with 2 columns.
+    </p>
+  </info>
+  <fo>
+    <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
+      <fo:layout-master-set>
+        <fo:simple-page-master master-name="normal" page-width="320pt" page-height="1in">
+          <fo:region-body column-count="2" column-gap="10pt"/>
+        </fo:simple-page-master>
+      </fo:layout-master-set>
+      <fo:page-sequence master-reference="normal">
+        <fo:flow flow-name="xsl-region-body">
+          <fo:block span="all">
+            <fo:block>This line is spanned over all columns.</fo:block>
+          </fo:block>
+          <fo:block>
+            <fo:block>line1</fo:block>
+            <fo:block>line2</fo:block>
+            <fo:block>line3</fo:block>
+            <fo:block>line4</fo:block>
+            <fo:block>line5</fo:block>
+            <fo:block>line6</fo:block>
+            <fo:block>line7</fo:block>
+            <fo:block>line8</fo:block>
+            <fo:block>line9</fo:block>
+            <fo:block>line10</fo:block>
+            <fo:block>line11</fo:block>
+            <fo:block>line12</fo:block>
+            <fo:block>line13</fo:block>
+          </fo:block>
+          <fo:block span="all">
+            <fo:block>This line is spanned over all columns.</fo:block>
+          </fo:block>
+        </fo:flow>
+      </fo:page-sequence>
+    </fo:root>
+  </fo>
+  <checks>
+    <eval expected="2" xpath="count(//pageViewport)"/>
+
+    <eval expected="14400" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[1]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[1]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[2]/@bpd"/>
+
+    <eval expected="43200" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/@bpd"/>
+    <eval expected="43200" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[1]/@bpd"/>
+    <eval expected="28800" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[2]/@bpd"/>
+    <eval expected="14400" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[2]/@bpd"/>
+  </checks>
+</testcase>

diff --git a/test/layoutengine/standard-testcases/region-body_column-count_balance_4col.xml b/test/layoutengine/standard-testcases/region-body_column-count_balance_4col.xml
new file mode 100644 (file)
index 0000000..5e131b1
--- /dev/null
+++ b/test/layoutengine/standard-testcases/region-body_column-count_balance_4col.xml
@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Copyright 2005 The Apache Software Foundation
+
+  Licensed 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 multi-column documents. Checks column balancing with 4 columns.
+    </p>
+  </info>
+  <fo>
+    <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
+      <fo:layout-master-set>
+        <fo:simple-page-master master-name="normal" page-width="320pt" page-height="1in">
+          <fo:region-body column-count="4" column-gap="10pt"/>
+        </fo:simple-page-master>
+      </fo:layout-master-set>
+      <fo:page-sequence master-reference="normal">
+        <fo:flow flow-name="xsl-region-body">
+          <fo:block span="all">
+            <fo:block>This line is spanned over all columns.</fo:block>
+          </fo:block>
+          <fo:block>
+            <fo:block>line1</fo:block>
+            <fo:block>line2</fo:block>
+            <fo:block>line3</fo:block>
+            <fo:block>line4</fo:block>
+            <fo:block>line5</fo:block>
+            <fo:block>line6</fo:block>
+            <fo:block>line7</fo:block>
+            <fo:block>line8</fo:block>
+            <fo:block>line9</fo:block>
+            <fo:block>line10</fo:block>
+            <fo:block>line11</fo:block>
+            <fo:block>line12</fo:block>
+            <fo:block>line13</fo:block>
+            <fo:block>line14</fo:block>
+            <fo:block>line15</fo:block>
+            <fo:block>line16</fo:block>
+            <fo:block>line17</fo:block>
+            <fo:block>line18</fo:block>
+            <fo:block>line19</fo:block>
+            <fo:block>line20</fo:block>
+            <fo:block>line21</fo:block>
+            <fo:block>line22</fo:block>
+            <fo:block>line23</fo:block>
+          </fo:block>
+          <fo:block span="all">
+            <fo:block>This line is spanned over all columns.</fo:block>
+          </fo:block>
+        </fo:flow>
+      </fo:page-sequence>
+    </fo:root>
+  </fo>
+  <checks>
+    <eval expected="2" xpath="count(//pageViewport)"/>
+
+    <eval expected="14400" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[1]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[1]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[2]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[3]/@bpd"/>
+    <eval expected="57600" xpath="//pageViewport[@nr=1]/page/regionViewport/regionBody/mainReference/span[2]/flow[4]/@bpd"/>
+
+    <true xpath="sum(//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span/@bpd) &lt;= //pageViewport[@nr=2]/page/regionViewport/regionBody/@bpd"/>
+    <eval expected="28800" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/@bpd"/>
+    <eval expected="28800" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[1]/@bpd"/>
+    <eval expected="28800" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[2]/@bpd"/>
+    <eval expected="28800" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[3]/@bpd"/>
+    <eval expected="14400" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[1]/flow[4]/@bpd"/>
+    <eval expected="14400" xpath="//pageViewport[@nr=2]/page/regionViewport/regionBody/mainReference/span[2]/@bpd"/>
+  </checks>
+</testcase>