1. Output constant types (RENDER_PDF, RENDER_PS, etc.) made common between

CommandLineOptions and Driver, and factored into fo.Constants interface.

2. New Driver(AWTRenderer renderer) constructor added in apps.Driver for
the AWTRenderer (which does reloading, unique among the output types.)  Note
reloading currently doesn't work--AWTRenderer not yet functional.

3. Driver.hasData() method removed from API--a search on when it was implemented
dates it to 2001, when reset() was coded.  Unsure of its need, and so
removed until we have user requests for it.

4. Renderers abstracted away from API in favor of just calling .setRenderer(int Rendertype),
and configuring user-configurable options in FOUserAgent.

5. Driver.setRenderer(String <renderer class name>) also dropped.  If external user
need for it, can be re-implemented fairly easily via a "renderer override" string in FOUserAgent, for which FOTreeHandler can read and use instead.

6. Validity checking added to fo:flow, and convenience functions defining the "%block;"
parameter entity and neutral containers as defined in 6.2 of spec [1] added to FObj.

[1] http://www.w3.org/TR/2001/REC-xsl-20011015/slice6.html#section-N9447-Formatting-Object-Content


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@197745 13f79535-47bb-0310-9956-ffa450edef68

10 files changed, 155 insertions, 189 deletions

diff --git a/src/java/org/apache/fop/apps/CommandLineOptions.java b/src/java/org/apache/fop/apps/CommandLineOptions.java
index 2497131cb..0689702b3 100644
--- a/src/java/org/apache/fop/apps/CommandLineOptions.java
+++ b/src/java/org/apache/fop/apps/CommandLineOptions.java
@@ -23,6 +23,8 @@ import java.io.FileNotFoundException;
 import java.util.Locale;
 import java.util.Vector;
 
+import org.apache.fop.fo.Constants;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.commons.logging.impl.SimpleLog;
@@ -30,34 +32,7 @@ import org.apache.commons.logging.impl.SimpleLog;
 /**
  * Options parses the commandline arguments
  */
-public class CommandLineOptions {
-
-    /** input / output not set */
-    public static final int NOT_SET = 0;
-    /** input: fo file */
-    public static final int FO_INPUT = 1;
-    /** input: xml+xsl file */
-    public static final int XSLT_INPUT = 2;
-    /** output: pdf file */
-    public static final int PDF_OUTPUT = 1;
-    /** output: screen using swing */
-    public static final int AWT_OUTPUT = 2;
-    /** output: mif file */
-    public static final int MIF_OUTPUT = 3;
-    /** output: sent swing rendered file to printer */
-    public static final int PRINT_OUTPUT = 4;
-    /** output: pcl file */
-    public static final int PCL_OUTPUT = 5;
-    /** output: postscript file */
-    public static final int PS_OUTPUT = 6;
-    /** output: text file */
-    public static final int TXT_OUTPUT = 7;
-    /** output: svg file */
-    public static final int SVG_OUTPUT = 8;
-    /** output: XML area tree */
-    public static final int AREA_OUTPUT = 9;
-    /** output: RTF file */
-    public static final int RTF_OUTPUT = 10;
+public class CommandLineOptions implements Constants {
 
     /* show configuration information */
     private Boolean showConfiguration = Boolean.FALSE;
@@ -257,12 +232,12 @@ public class CommandLineOptions {
     }
 
     private int parseAWTOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(AWT_OUTPUT);
+        setOutputMode(RENDER_AWT);
         return 0;
     }
 
     private int parsePDFOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(PDF_OUTPUT);
+        setOutputMode(RENDER_PDF);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the pdf output file");
@@ -273,7 +248,7 @@ public class CommandLineOptions {
     }
 
     private int parseMIFOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(MIF_OUTPUT);
+        setOutputMode(RENDER_MIF);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the mif output file");
@@ -284,7 +259,7 @@ public class CommandLineOptions {
     }
 
     private int parseRTFOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(RTF_OUTPUT);
+        setOutputMode(RENDER_RTF);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the rtf output file");
@@ -295,12 +270,12 @@ public class CommandLineOptions {
     }
 
     private int parsePrintOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(PRINT_OUTPUT);
+        setOutputMode(RENDER_PRINT);
         return 0;
     }
 
     private int parsePCLOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(PCL_OUTPUT);
+        setOutputMode(RENDER_PCL);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the pdf output file");
@@ -311,7 +286,7 @@ public class CommandLineOptions {
     }
 
     private int parsePostscriptOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(PS_OUTPUT);
+        setOutputMode(RENDER_PS);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the PostScript output file");
@@ -322,7 +297,7 @@ public class CommandLineOptions {
     }
 
     private int parseTextOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(TXT_OUTPUT);
+        setOutputMode(RENDER_TXT);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the text output file");
@@ -333,7 +308,7 @@ public class CommandLineOptions {
     }
 
     private int parseSVGOutputOption(String[] args, int i) throws FOPException {
-        setOutputMode(SVG_OUTPUT);
+        setOutputMode(RENDER_SVG);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the svg output file");
@@ -348,7 +323,7 @@ public class CommandLineOptions {
             inputmode = FO_INPUT;
             fofile = new File(args[i]);
         } else if (outputmode == NOT_SET) {
-            outputmode = PDF_OUTPUT;
+            outputmode = RENDER_PDF;
             outfile = new File(args[i]);
         } else {
             throw new FOPException("Don't know what to do with "
@@ -358,7 +333,7 @@ public class CommandLineOptions {
     }
 
     private int parseAreaTreeOption(String[] args, int i) throws FOPException {
-        setOutputMode(AREA_OUTPUT);
+        setOutputMode(RENDER_XML);
         if ((i + 1 == args.length)
                 || (args[i + 1].charAt(0) == '-')) {
             throw new FOPException("you must specify the area-tree output file");
@@ -388,7 +363,7 @@ public class CommandLineOptions {
             throw new FOPException("No output file specified");
         }
 
-        if ((outputmode == AWT_OUTPUT || outputmode == PRINT_OUTPUT) && outfile != null) {
+        if ((outputmode == RENDER_AWT || outputmode == RENDER_PRINT) && outfile != null) {
             throw new FOPException("Output file may not be specified " +
                 "for AWT or PRINT output");
         }
@@ -446,26 +421,26 @@ public class CommandLineOptions {
         switch (outputmode) {
         case NOT_SET:
             throw new FOPException("Renderer has not been set!");
-        case PDF_OUTPUT:
+        case RENDER_PDF:
             return Driver.RENDER_PDF;
-        case AWT_OUTPUT:
+        case RENDER_AWT:
             return Driver.RENDER_AWT;
-        case MIF_OUTPUT:
+        case RENDER_MIF:
             return Driver.RENDER_MIF;
-        case PRINT_OUTPUT:
+        case RENDER_PRINT:
             return Driver.RENDER_PRINT;
-        case PCL_OUTPUT:
+        case RENDER_PCL:
             return Driver.RENDER_PCL;
-        case PS_OUTPUT:
+        case RENDER_PS:
             return Driver.RENDER_PS;
-        case TXT_OUTPUT:
+        case RENDER_TXT:
             return Driver.RENDER_TXT;
-        case SVG_OUTPUT:
+        case RENDER_SVG:
             return Driver.RENDER_SVG;
-        case AREA_OUTPUT:
+        case RENDER_XML:
             foUserAgent.getRendererOptions().put("fineDetail", isCoarseAreaXml());
             return Driver.RENDER_XML;
-        case RTF_OUTPUT:
+        case RENDER_RTF:
             return Driver.RENDER_RTF;
         default:
             throw new FOPException("Invalid Renderer setting!");
@@ -505,7 +480,7 @@ public class CommandLineOptions {
     }
 
     /**
-     * Returns the output mode (output format, ex. NOT_SET or PDF_OUTPUT)
+     * Returns the output mode (output format, ex. NOT_SET or RENDER_PDF)
      * @return the output mode
      */
     public int getOutputMode() {
@@ -653,45 +628,45 @@ public class CommandLineOptions {
         case NOT_SET:
             log.info("not set");
             break;
-        case PDF_OUTPUT:
+        case RENDER_PDF:
             log.info("pdf");
             log.info("output file: " + outfile.toString());
             break;
-        case AWT_OUTPUT:
+        case RENDER_AWT:
             log.info("awt on screen");
             if (outfile != null) {
                 log.error("awt mode, but outfile is set:");
                 log.info("out file: " + outfile.toString());
             }
             break;
-        case MIF_OUTPUT:
+        case RENDER_MIF:
             log.info("mif");
             log.info("output file: " + outfile.toString());
             break;
-        case RTF_OUTPUT:
+        case RENDER_RTF:
             log.info("rtf");
             log.info("output file: " + outfile.toString());
             break;
-        case PRINT_OUTPUT:
+        case RENDER_PRINT:
             log.info("print directly");
             if (outfile != null) {
                 log.error("print mode, but outfile is set:");
                 log.error("out file: " + outfile.toString());
             }
             break;
-        case PCL_OUTPUT:
+        case RENDER_PCL:
             log.info("pcl");
             log.info("output file: " + outfile.toString());
             break;
-        case PS_OUTPUT:
+        case RENDER_PS:
             log.info("PostScript");
             log.info("output file: " + outfile.toString());
             break;
-        case TXT_OUTPUT:
+        case RENDER_TXT:
             log.info("txt");
             log.info("output file: " + outfile.toString());
             break;
-        case SVG_OUTPUT:
+        case RENDER_SVG:
             log.info("svg");
             log.info("output file: " + outfile.toString());
             break;
diff --git a/src/java/org/apache/fop/apps/Driver.java b/src/java/org/apache/fop/apps/Driver.java
index 2a96d8039..e1287740e 100644
--- a/src/java/org/apache/fop/apps/Driver.java
+++ b/src/java/org/apache/fop/apps/Driver.java
@@ -30,6 +30,7 @@ import org.xml.sax.XMLReader;
 import org.w3c.dom.Document;
 
 // FOP
+import org.apache.fop.fo.Constants;
 import org.apache.fop.fo.ElementMapping;
 import org.apache.fop.fo.FOTreeBuilder;
 import org.apache.fop.fo.FOInputHandler;
@@ -86,62 +87,7 @@ import org.apache.fop.tools.DocumentReader;
  * driver.render(parser, fileInputSource(args[0]));
  * </PRE>
  */
-public class Driver {
-
-    /**
-     * private constant to indicate renderer was not defined.
-     */
-    private static final int NOT_SET = 0;
-
-    /**
-     * Render to PDF. OutputStream must be set
-     */
-    public static final int RENDER_PDF = 1;
-
-    /**
-     * Render to a GUI window. No OutputStream neccessary
-     */
-    public static final int RENDER_AWT = 2;
-
-    /**
-     * Render to MIF. OutputStream must be set
-     */
-    public static final int RENDER_MIF = 3;
-
-    /**
-     * Render to XML. OutputStream must be set
-     */
-    public static final int RENDER_XML = 4;
-
-    /**
-     * Render to PRINT. No OutputStream neccessary
-     */
-    public static final int RENDER_PRINT = 5;
-
-    /**
-     * Render to PCL. OutputStream must be set
-     */
-    public static final int RENDER_PCL = 6;
-
-    /**
-     * Render to Postscript. OutputStream must be set
-     */
-    public static final int RENDER_PS = 7;
-
-    /**
-     * Render to Text. OutputStream must be set
-     */
-    public static final int RENDER_TXT = 8;
-
-    /**
-     * Render to SVG. OutputStream must be set
-     */
-    public static final int RENDER_SVG = 9;
-
-    /**
-     * Render to RTF. OutputStream must be set
-     */
-    public static final int RENDER_RTF = 10;
+public class Driver implements Constants {
 
     /**
      * the FO tree builder
@@ -191,6 +137,15 @@ public class Driver {
     }
 
     /**
+     * Constructor for AWTRenderer, which reuses the
+     * same renderer instance for document reloading
+     */
+    public Driver(AWTRenderer renderer) {
+        this();
+        setRenderer(renderer);
+    }
+
+    /**
      * Convenience constructor for directly setting input and output.
      * @param source InputSource to take the XSL-FO input from
      * @param stream Target output stream
@@ -222,8 +177,15 @@ public class Driver {
      */
     public void setUserAgent(FOUserAgent agent) {
         userAgent = agent;
+        if (renderer != null) {
+            renderer.setUserAgent(userAgent);
+        }
     }
 
+    /**
+     * Get the FOUserAgent instance for this process
+     * @return the user agent
+     */
     public FOUserAgent getUserAgent() {
         if (userAgent == null) {
             userAgent = new FOUserAgent();
@@ -246,14 +208,6 @@ public class Driver {
     }
 
     /**
-     * Indicates whether FOP has already received input data.
-     * @return true, if input data was received
-     */
-    public boolean hasData() {
-        return (treeBuilder.hasData());
-    }
-
-    /**
      * Set the OutputStream to use to output the result of the Renderer
      * (if applicable)
      * @param stream the stream to output the result of rendering to
@@ -287,7 +241,7 @@ public class Driver {
     }
 
     /**
-     * Shortcut to set the rendering type to use. Must be one of
+     * Method to set the rendering type to use. Must be one of
      * <ul>
      * <li>RENDER_PDF</li>
      * <li>RENDER_AWT</li>
@@ -307,31 +261,31 @@ public class Driver {
         rendererType = renderer;
         switch (renderer) {
         case RENDER_PDF:
-            setRenderer("org.apache.fop.render.pdf.PDFRenderer");
+            setRenderer(new org.apache.fop.render.pdf.PDFRenderer());
             break;
         case RENDER_AWT:
-            setRenderer("org.apache.fop.render.awt.AWTRenderer");
+            setRenderer(new org.apache.fop.render.awt.AWTRenderer());
             break;
         case RENDER_PRINT:
-            setRenderer("org.apache.fop.render.awt.AWTPrintRenderer");
+            setRenderer(new org.apache.fop.render.awt.AWTPrintRenderer());
             break;
         case RENDER_PCL:
-            setRenderer("org.apache.fop.render.pcl.PCLRenderer");
+            setRenderer(new org.apache.fop.render.pcl.PCLRenderer());
             break;
         case RENDER_PS:
-            setRenderer("org.apache.fop.render.ps.PSRenderer");
+            setRenderer(new org.apache.fop.render.ps.PSRenderer());
             break;
         case RENDER_TXT:
-            setRenderer("org.apache.fop.render.txt.TXTRenderer()");
+            setRenderer(new org.apache.fop.render.txt.TXTRenderer());
             break;
         case RENDER_MIF:
             //foInputHandler will be set later
             break;
         case RENDER_XML:
-            setRenderer("org.apache.fop.render.xml.XMLRenderer");
+            setRenderer(new org.apache.fop.render.xml.XMLRenderer());
             break;
         case RENDER_SVG:
-            setRenderer("org.apache.fop.render.svg.SVGRenderer");
+            setRenderer(new org.apache.fop.render.svg.SVGRenderer());
             break;
         case RENDER_RTF:
             //foInputHandler will be set later
@@ -346,46 +300,12 @@ public class Driver {
      * Set the Renderer to use.
      * @param renderer the renderer instance to use
      */
-    public void setRenderer(Renderer renderer) {
-        // AWTStarter calls this function directly
-        if (renderer instanceof AWTRenderer) {
-            rendererType = RENDER_AWT;
-        }
+    private void setRenderer(Renderer renderer) {
         renderer.setUserAgent(getUserAgent());
-        userAgent.setProducer("FOP Version" + Fop.getVersion());
         this.renderer = renderer;
     }
 
     /**
-     * Set the class name of the Renderer to use as well as the
-     * producer string for those renderers that can make use of it.
-     * @param rendererClassName classname of the renderer to use such as
-     * "org.apache.fop.render.pdf.PDFRenderer"
-     * @exception IllegalArgumentException if the classname was invalid.
-     * @see #setRenderer(int)
-     */
-    public void setRenderer(String rendererClassName)
-                throws IllegalArgumentException {
-        try {
-            renderer = (Renderer)Class.forName(rendererClassName).newInstance();
-            renderer.setUserAgent(getUserAgent());
-            userAgent.setProducer("FOP Version" + Fop.getVersion());
-        } catch (ClassNotFoundException e) {
-            throw new IllegalArgumentException("Could not find "
-                                               + rendererClassName);
-        } catch (InstantiationException e) {
-            throw new IllegalArgumentException("Could not instantiate "
-                                               + rendererClassName);
-        } catch (IllegalAccessException e) {
-            throw new IllegalArgumentException("Could not access "
-                                               + rendererClassName);
-        } catch (ClassCastException e) {
-            throw new IllegalArgumentException(rendererClassName
-                                               + " is not a renderer");
-        }
-    }
-
-    /**
      * Add the given element mapping.
      * An element mapping maps element names to Java classes.
      *
diff --git a/src/java/org/apache/fop/apps/FOUserAgent.java b/src/java/org/apache/fop/apps/FOUserAgent.java
index b84d17bbc..45ca4f77f 100644
--- a/src/java/org/apache/fop/apps/FOUserAgent.java
+++ b/src/java/org/apache/fop/apps/FOUserAgent.java
@@ -64,7 +64,7 @@ public class FOUserAgent {
     /** Producer:  Metadata element for the system/software that produces
      * the document. (Some renderers can store this in the document.)
      */
-    protected String producer = "FOP " + Fop.getVersion();
+    protected String producer = "FOP Version " + Fop.getVersion();
 
     /** Creator:  Metadata element for the user that created the
      * document. (Some renderers can store this in the document.)
diff --git a/src/java/org/apache/fop/apps/Fop.java b/src/java/org/apache/fop/apps/Fop.java
index 7376c9bbe..6db94af9e 100644
--- a/src/java/org/apache/fop/apps/Fop.java
+++ b/src/java/org/apache/fop/apps/Fop.java
@@ -64,7 +64,7 @@ public class Fop {
             // System.exit(0) called to close AWT/SVG-created threads, if any.
             // AWTRenderer closes with window shutdown, so exit() should not
             // be called here
-            if (options.getOutputMode() != CommandLineOptions.AWT_OUTPUT) {
+            if (options.getOutputMode() != CommandLineOptions.RENDER_AWT) {
                 System.exit(0);
             }
         } catch (FOPException e) {
diff --git a/src/java/org/apache/fop/fo/Constants.java b/src/java/org/apache/fop/fo/Constants.java
index 5309bcf1a..3e9bd22ef 100644
--- a/src/java/org/apache/fop/fo/Constants.java
+++ b/src/java/org/apache/fop/fo/Constants.java
@@ -21,8 +21,38 @@ package org.apache.fop.fo;
 
 public interface Constants {
 
+    /* These constants are used by apps.CommandLineOptions and
+       apps.Driver to describe the input (either .FO or .XML/.XSL)
+       and desired output (PDF, PS, AWT, etc.) of the document */
+       
+    /** input / output not set */
+    int NOT_SET = 0;
+    /** input: fo file */
+    int FO_INPUT = 1;
+    /** input: xml+xsl file */
+    int XSLT_INPUT = 2;
+    /** output: pdf file */
+    int RENDER_PDF = 1;
+    /** output: screen using swing */
+    int RENDER_AWT = 2;
+    /** output: mif file */
+    int RENDER_MIF = 3;
+    /** output: sent swing rendered file to printer */
+    int RENDER_PRINT = 4;
+    /** output: pcl file */
+    int RENDER_PCL = 5;
+    /** output: postscript file */
+    int RENDER_PS = 6;
+    /** output: text file */
+    int RENDER_TXT = 7;
+    /** output: svg file */
+    int RENDER_SVG = 8;
+    /** output: XML area tree */
+    int RENDER_XML = 9;
+    /** output: RTF file */
+    int RENDER_RTF = 10;
+    
     // element constants
-
     int FO_BASIC_LINK = 1;
     int FO_BIDI_OVERRIDE = 2;
     int FO_BLOCK = 3;
diff --git a/src/java/org/apache/fop/fo/FOTreeBuilder.java b/src/java/org/apache/fop/fo/FOTreeBuilder.java
index e8be41305..eef720a45 100644
--- a/src/java/org/apache/fop/fo/FOTreeBuilder.java
+++ b/src/java/org/apache/fop/fo/FOTreeBuilder.java
@@ -305,14 +305,6 @@ public class FOTreeBuilder extends DefaultHandler {
         foInputHandler = null;
     }
 
-    /**
-     * Indicates if data has been processed.
-     * @return True if data has been processed
-     */
-    public boolean hasData() {
-        return (rootFObj != null);
-    }
-
 }
 
 // code stolen from org.apache.batik.util and modified slightly
diff --git a/src/java/org/apache/fop/fo/FObj.java b/src/java/org/apache/fop/fo/FObj.java
index ac90c68a8..ec4864fac 100644
--- a/src/java/org/apache/fop/fo/FObj.java
+++ b/src/java/org/apache/fop/fo/FObj.java
@@ -441,5 +441,39 @@ public class FObj extends FONode implements Constants {
         return null;
     }
 
+    /**
+     * Convenience method for validity checking.  Checks if the
+     * incoming node is a member of the "%block;" parameter entity
+     * as defined in Sect. 6.2 of the XSL 1.0 & 1.1 Recommendations
+     * @param nsURI namespace URI of incoming invalid node
+     * @param lName local name (i.e., no prefix) of incoming node 
+     * @return true if a member, false if not
+     */
+    protected static boolean isBlockItem(String nsURI, String lName) {
+        return (nsURI == FOElementMapping.URI && 
+            (lName.equals("block") 
+            || lName.equals("table") 
+            || lName.equals("table-and-caption") 
+            || lName.equals("block-container")
+            || lName.equals("list-block") 
+            || lName.equals("float")))
+            || isNeutralItem(nsURI, lName);
+    }
+
+    /**
+     * Convenience method for validity checking.  Checks if the
+     * incoming node is a member of the neutral item list
+     * as defined in Sect. 6.2 of the XSL 1.0 & 1.1 Recommendations
+     * @param nsURI namespace URI of incoming invalid node
+     * @param lName local name (i.e., no prefix) of incoming node 
+     * @return true if a member, false if not
+     */
+    protected static boolean isNeutralItem(String nsURI, String lName) {
+        return (nsURI == FOElementMapping.URI && 
+            (lName.equals("multi-switch") 
+            || lName.equals("multi-properties")
+            || lName.equals("wrapper") 
+            || lName.equals("retrieve-marker")));
+    }
 }
 
diff --git a/src/java/org/apache/fop/fo/pagination/Flow.java b/src/java/org/apache/fop/fo/pagination/Flow.java
index ac2911e9d..d7cc88cf3 100644
--- a/src/java/org/apache/fop/fo/pagination/Flow.java
+++ b/src/java/org/apache/fop/fo/pagination/Flow.java
@@ -23,6 +23,7 @@ import java.util.ArrayList;
 
 // XML
 import org.xml.sax.Attributes;
+import org.xml.sax.Locator;
 
 // FOP
 import org.apache.fop.fo.FONode;
@@ -63,6 +64,28 @@ public class Flow extends FObj {
     }
 
     /**
+     * @see org.apache.fop.fo.FONode#validateChildNode(Locator, String, String)
+     * XSL/FOP Content Model: (%block;)+
+     */
+    protected void validateChildNode(Locator loc, String nsURI, String localName) {
+        if (!isBlockItem(nsURI, localName)) {
+            invalidChildError(loc, nsURI, localName);
+        }
+    }
+
+    /**
+     * Make sure content model satisfied, if so then tell the
+     * StructureRenderer that we are at the end of the flow.
+     * @see org.apache.fop.fo.FONode#end
+     */
+    protected void end() {
+        if (children == null) {
+            missingChildElementError("(%block;)+");
+        }
+        getFOInputHandler().endFlow(this);
+    }
+
+    /**
      * @see org.apache.fop.fo.FObj#addProperties
      */
     protected void addProperties(Attributes attlist) throws FOPException {
@@ -96,13 +119,6 @@ public class Flow extends FObj {
     }
 
     /**
-     * Tell the StructureRenderer that we are at the end of the flow.
-     */
-    protected void end() {
-        getFOInputHandler().endFlow(this);
-    }
-
-    /**
      * @param name the name of the flow to set
      * @throws FOPException for an empty name
      */
diff --git a/src/java/org/apache/fop/fo/pagination/LayoutMasterSet.java b/src/java/org/apache/fop/fo/pagination/LayoutMasterSet.java
index e2919c3de..a97cbae1e 100644
--- a/src/java/org/apache/fop/fo/pagination/LayoutMasterSet.java
+++ b/src/java/org/apache/fop/fo/pagination/LayoutMasterSet.java
@@ -74,7 +74,7 @@ public class LayoutMasterSet extends FObj {
      */
     protected void end() {
         if (children == null) {
-           missingChildElementError("(simple-page-master|page-sequence-master)+");
+            missingChildElementError("(simple-page-master|page-sequence-master)+");
         }
     }
 
diff --git a/src/java/org/apache/fop/render/awt/viewer/PreviewDialog.java b/src/java/org/apache/fop/render/awt/viewer/PreviewDialog.java
index c1d06615c..8a09828f1 100644
--- a/src/java/org/apache/fop/render/awt/viewer/PreviewDialog.java
+++ b/src/java/org/apache/fop/render/awt/viewer/PreviewDialog.java
@@ -384,8 +384,7 @@ public class PreviewDialog extends JFrame {
     private class Reloader extends Thread {
         public void run() {
             if (driver == null) {
-                driver = new Driver();
-                driver.setRenderer(renderer);
+                driver = new Driver(renderer);
             } else {
                 driver.reset();
             }