J2TreePrinter is a Java 2 component for printing multi-page JTree documents.  J2TreePrinter converts any JTree or JTree subclass into a Java Pageable, suitable for printing by the J2Printer class (or any Java PrinterJob).  It also implements Flowable for any JTree, so that it may be used with J2FlowPrinter as part of a series of Flowables printed back-to-back.

J2TreePrinter Pagination

A J2TreePrinter instance will print a JTree as a Pageable. J2TreePrinter paginates JTree instances across multiple pages vertically, breaking the JTree on row (tree node) boundaries. A JTree that is too wide horizontally will be rescaled to fit the page width. The JTree can be left, right, or center justified horizontally, and top, bottom, or center justified vertically. You can also specify whether to draw an outside line around the JTree.


You will find it useful to begin your program with:

    import com.wildcrest.j2printerworks.*;

rather than spell out the full package name for all J2PrinterWorks classes.

J2TreePrinter can instantiated with a zero-argument constructor:

    J2TreePrinter treePrinter = new J2TreePrinter();

This creates a J2TreePrinter object and initializes all values to their defaults (see the J2TreePrinter Javadoc documentation ).  To specify the JTree to be printed by J2TreePrinter, you can use the J2TreePrinter method setTree:
At this point treePrinter is a Pageable suitable for printing by J2Printer.

Alternatively, you can use the single-argument J2TreePrinter constructor:

    J2TreePrinter treePrinter = new J2TreePrinter(yourJTree);

The following is a simple but complete Java program (J2TreePrinterSimplestTest.java ) that displays and prints a JTree using J2TreePrinter:

import javax.swing.*;
import com.wildcrest.j2printerworks.*;

class J2TreePrinterSimplestTest{
    static public void main(String args[]){
        JTree tree = new JTree();    // has default content
        for (int i=0; i<tree.getRowCount(); i++) tree.expandRow(i);

        JFrame frame = new JFrame("J2TreePrinter test");

        J2Printer printer = new J2Printer();
        J2TreePrinter treePrinter = new J2TreePrinter(tree);


Most of the methods of J2TreePrinter are set and get methods for controlling its property values. The full list of J2TreePrinter methods, what they do, and their default values are given in the J2TreePrinter Javadoc documentation .

General properties

Whether J2TreePrinter is used as a Pageable or a Flowable, you can control whether it is left, right, or center justified horizontally on a page, top, bottom, or center justified within the remaining space on a page, and whether to draw an outside line around the JTree.

Horizontal and vertical alignment

J2TreePrinter will print your JTree either left, center, or right justified horizontally on the page between the left and right margins.  The default value for horizontal alignment is CENTER.

Similarly, J2TreePrinter will print your JTree either top, center, or bottom justified vertically on the page between the gap below the header and gap above the footer.  The default value for vertical alignment is TOP.

setHorizontalAlignment (int horizontalAlignment)
          Sets the horizontal alignment (LEFT, CENTER, RIGHT) for printing the JTree on the page.

setVerticalAlignment (int verticalAlignment)
          Sets the vertical alignment (TOP, CENTER, BOTTOM) for printing the JTree on the page.

Outside line

J2TreePrinter lets you control whether to draw a line surrounding the JTree and what color this line should be using the following methods:

setOutsideLines (boolean showOutsideLines)
          Sets whether to print outside border lines around JTree.

setOutsideLineColor (java.awt.Color outsideLineColor)
          Sets Color of outside border lines.

Pageable properties

When J2TreePrinter is used as a Pageable, it can have its own ("local") headers & footers (left, center, and right), margins (left, right, top, and bottom), and orientation (portrait & landscape).  Headers and footers can be specified as a String or a JLabel, can be different on the first page vs. the rest of the pages of the Pageable, and can include date, time, and page numbering.  The methods are the same as the parallel set of methods described in the J2Printer section under "Pageable properties".

If "local" values are not specified for this J2TreePrinter instance, the "global" (overall, default) values set using the parallel J2Printer methods will be used.  You can force the J2Printer "global" values to be used by calling the J2TreePrinter method(s) with the argument J2Printer.GLOBAL.

The Pageable properties of J2TreePrinter will be ignored when the J2TreePrinter is used as a Flowable.  This is because in this case the Pageable is the containing J2FlowPrinter, so page properties such as headers, footers, margins, and orientation will be controlled by the J2FlowPrinter Pageable, not the J2TreePrinter used as a Flowable. Note, however, that scaling does work for J2TreePrinter used as either a Pageable or a Flowable, that is, the J2TreePrinter can appear at its own scale within an overall J2FlowPrinter sequence.

Fit-to-page scaling

In addition to regular percentage scaling accomplished using the setScale method, J2TreePrinter also supports fit-to-page scaling when J2TreePrinter is used as a Pageable using the following method:

setMaximumPages (int pagesHigh)
          Set the maximum number of vertical pages for printing this J2TreePrinter (will minify to fit).

The setMaximumPages method causes your J2TreePrinter to be scaled down until it fits within pagesHigh pages vertically.  This method cannot be used to magnify and instead will only minify your J2TreePrinter (hence the name setMaximumPages).  The method works by starting at a scale of 1.0 and reducing the scale in increments of 0.005 (half a percent) until your J2TreePrinter fits within the prescribed limits.  If pagesHigh is set to 0 or less, this is taken as a signal that the scaling is unconstrained, that is, the J2TreePrinter can use as many pages as it needs.

NOTE: This method causes the rescaling to take place at the time it is called and does NOT remember or maintain the page limits you specify. Thus, if you change any printing parameters including your document content, headers, footers, margins, paper size, orientation, etc., you must call setMaximumPages again.

The percentage and fit-to-page scaling features interact.  You can call setMaximumPages(pagesHigh) to specify a number of pages and then use the method getScale() to find out the resulting scaling factor.  Or you can call setScale(factor) to scale to a desired percentage and then use getNumberOfPages() to find out the number of resulting pages.  The getNumberOfPages() method works for both magnification and minification (thus you could use it to implement your own fit-to-page feature for magnification, which you might call setMinimumPages(pagesHigh) ).

Additional features

J2TreePrinter WYSIWYG support

J2TreePrinter inherently performs WYSIWYG printing since it images your JTree instance directly using the Java print and paint methods.  This means you will print all of your JTree's specified fonts, node formats, colors, etc.  If you subclass JTree and provide your own custom cell renderers, these also will be displayed and printed.  The general rule is: whatever your JTree can display, J2TreePrinter will print.

Non-GUI JTree printing

It is not necessary that the JTree you print be in a JFrame visible on the screen.  You may be printing from a server application and have no display.  Or you may have a JTree displayed but wish to print from a different non-GUI copy of the JTree.  The latter situation can arise when you want to set the printing JTree properties different from your on-screen JTree display, such as to force different node expansion, colors, or fonts as appropriate for a printed page.  In such cases, you can use code like:

  JTree tree2 = new JTree();
  tree2.setSize(tree2.getPreferredSize()); // size required

Java Borders

You can use the Java Swing Borders classes to add various kinds of borders to your JTree, and these will be printed by J2TreePrinter.  Borders work when using J2TreePrinter as either a Pageable or a Flowable.  You can use both the Java Borders feature and the J2TreePrinter method setOutsideLines(true) at the same time (the Java Border will be inside the outside line).  Some examples of Java Borders are:
    jTree1.setBorder(new LineBorder(Color.green,20));
    jTree1.setBorder(new EmptyBorder(10,10,10,10));
    jTree1.setBorder(new CompoundBorder(new LineBorder(Color.green,20),new EmptyBorder(10,10,10,10)));

Using J2TreePrinter as a JavaBean

The J2PrinterWorks components are designed to work as a JavaBeans components in visual builder environments.  However, J2PrinterWorks uses APIs unique to the Java 2 system, and not all visual development environments currently work and build visually with Java 2-based components.  In particular, WebGain/Symantec Visual Cafe has to be specially configured to allow you to import the J2PrinterWorks components into its component library and exhibits other problems when using it visually. In contrast, Borland JBuilder and IBM VisualAge for Java can read and use J2PrinterWorks.jar as either a set of JavaBeans components or programmatically as classes.  See Installation & Compatibility   for further details.  Since the J2PrinterWorks components are not GUI components per se, the need to work with them visually isn't great, so that using them programmatically isn't much of a limitation.

If J2PrinterWorks.jar is properly installed, you will see the J2PrinterWorks components, including J2Printer and J2TreePrinter, in the component palette of your visual programming environment.  Click on the J2Printer bean and drop it on your work area and likewise drag the J2TreePrinter bean and drop it on your work area.  You will see icons representing instances of these beans.  These will not be displayed at run-time.

When you bring up the property sheet for either component, you will be able to see and edit their properties.  The properties may be set as desired, with values as defined in the Javadoc documentation .

You can make the J2Printer bean print by using your visual programming environment to perform event wiring from an actionPerformed event such as a button push to the J2Printer "print" event target method.  You can use this to print the instance of J2TreePrinter, using the setTree method or the J2TreePrinter constructor itself to specify your JTree.

All the J2PrinterWorks properties are bound properties.  You may use your visual programming environment to do property-to-property binding in either direction between the J2PrinterWorks components and your other beans.  None of the J2PrinterWorks properties are constrained properties.  This frees you from having to place try...catch blocks around your "set" calls in regular programming.

J2PrinterWorks components are fully serializable.  After customizing any properties, instances can be saved along with any other beans to which they may be wired.  When reloaded, the instances will come back with their customized values.  No J2PrinterWorks properties are declared transient.

Copyright 2009, Wildcrest Associates (http://www.wildcrest.com )