Index: src/main/java/org/apache/pdfbox/pdmodel/interactive/viewerpreferences/PDViewerPreferences.java
===================================================================
--- src/main/java/org/apache/pdfbox/pdmodel/interactive/viewerpreferences/PDViewerPreferences.java	(revisione 1163182)
+++ src/main/java/org/apache/pdfbox/pdmodel/interactive/viewerpreferences/PDViewerPreferences.java	(copia locale)
@@ -75,7 +75,13 @@
      * Boundary constant.
      */
     public static final String BOUNDARY_ART_BOX = "ArtBox";
+    
+    public static final String DUPLEX_SIMPLEX = "Simplex";
+    public static final String DUPLEX_FLIP_SHORT_EDGE = "DuplexFlipShortEdge";
+    public static final String DUPLEX_FLIP_LONG_EDGE = "DuplexFlipLongEdge";
 
+    public static final String PRINT_SCALING_NONE = "None";
+    public static final String PRINT_SCALING_APP_DEFAULT = "AppDefault";
 
     private COSDictionary prefs;
 
@@ -348,4 +354,44 @@
     {
         prefs.setName( "PrintClip", value );
     }
+    
+    /**
+     * Get the Duplex preference.  See DUPLEX_XXX constants.
+     *
+     * @return the Duplex preference.
+     */
+    public String getDuplex()
+    {
+        return prefs.getNameAsString( "Duplex" );
+    }
+
+    /**
+     * Set the Duplex preference.  See DUPLEX_XXX constants.
+     *
+     * @param value Set the Duplex preference.
+     */
+    public void setDuplex( String value )
+    {
+        prefs.setName( "Duplex", value );
+    }
+    
+    /**
+     * Get the PrintScaling preference.  See PRINT_SCALING_XXX constants.
+     *
+     * @return the PrintScaling preference.
+     */
+    public String getPrintScaling()
+    {
+        return prefs.getNameAsString( "PrintScaling" , PRINT_SCALING_APP_DEFAULT);
+    }
+
+    /**
+     * Set the PrintScaling preference.  See PRINT_SCALING_XXX constants.
+     *
+     * @param value Set the PrintScaling preference.
+     */
+    public void setPrintScaling( String value )
+    {
+        prefs.setName( "PrintScaling", value );
+    }
 }