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  J2ComponentPrinter
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Overview

J2ComponentPrinter is a Java 2 component for printing the contents of any Java Component or Component subclass.  Its general-purpose pagination capabilities make it appropriate for printing larger, multi-page Components, including many third-party Components, as well as Containers of Components, Images, and arbitrary diagrams and figures drawn with regular Java Graphics (or Graphics2D) method calls in a paint method. J2ComponentPrinter can print the Component as a Java Pageable or as a Flowable, so that it may be used with J2FlowPrinter as part of a series of Flowables printed back-to-back. 


J2ComponentPrinter Pagination

J2ComponentPrinter supports four pagination modes, which can be idependently specified in the horizontal and vertical directions.  The four pagination modes supported by J2ComponentPrinter are:

SHRINK_TO_FIT (the default for horizontal pagination) means shrink the Component to fit within a single page width and/or height..  If printing begins on a partial page, then skip to the next page if the available space is less than getMaximumPaginationGap() percent (default 20%) of the full page width and/or height.

TILE means print the Component across multiple horizontal and/or vertical pages without scaling by breaking the Component as necessary on pixel boundaries (rather than anything to do with the Component content). If beginning on a partial page, the value of getMaximumPaginationGap() determines when to start on a new page.

BREAK_ON_COMPONENTS means if the Compoennt is used as a Container, then examine its contained Components and find the maximum horizontal and/or vertical boundaries where page break(s) can be inserted without slicing through any Components. Only the first level of contained Components is examined, so the contents of any nested Containers will be kept together on the same page (unless larger than a page, in which case it will be sliced (like TILE) as needed on pixel boundaries). If beginning on a partial page, the value of getMaximumPaginationGap() determines when to start on a new page.

BREAK_ON_COLOR (the default for vertical pagination) means analyze the Component and determine the bottomost (for vertical pagination) or rightmost (for horizontal pagination) boundary that fits the remaining space on the page and whose pixel color values most closely match the specified (horizontal or vertical) break color.  For example, break on Color.white can be used for paginating JTextPane, JTree, JList, and many third-party Components.  Or, break on table.getGridColor() can be used for printing tables such as JTable (though J2TablePrinter also supports BREAK_ON_COLOR and, unlike J2ComponentPrinter, supports features such as column and header replication, subarea printing, and the like).  If beginning on a partial page, the value of getMaximumPaginationGap() determines when to start on a new page.  NOTE: The image color analsysis underlying BREAK_ON_COLOR mode can be slow for large Components.  See the methods setAutomaticRecalculation(boolean) and breakOnColorIncrement(int) for ways to optimize these calculations.

J2CompoentPrinter is similar to J2PanelPrinter in many ways, but is more general and can be used in place of J2PanelPrinter for most purposes.  The TILE and BREAK_ON_COMPONENTS modes are the same in J2ComponentPrinter and J2PanelPrinter, except that with J2ComponentPrinter you can invoke these modes independently in the horizontal and vertical directions.  Likewise, the SHRINK_TO_FIT mode of J2ComponentPrinter can be invoked independently in the horizontal and vertical directions and also honors the getMaximumPaginationGap() concept, whereas J2PanelPrinter has a special rule governing when to skip to a new page.  The BREAK_ON_COLOR mode of J2ComponentPrinter has no counterpart in J2PanelPrinter and makes J2ComponentPrinter capable of paginating a broader range of components effectively.

J2ComponentPrinter will print the Component either left, right, or center justified horizontally or top, bottom, or center justified vertically. You can specify whether to use a white background when printing the Component, and/or whether to draw an outside line around the Component.  J2ComponentPrinter prints the Component "WYSIWYG", so that the layout and relative size of the Component and all of its contents will be printed exactly as defined.
 

Programming

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.

J2ComponentPrinter can instantiated with a zero-argument constructor:
    J2ComponentPrinter component Printer = new J2ComponentPrinter();   

This creates a J2ComponentPrinter object and initializes all values to their defaults (see the J2ComponentPrinter Javadoc documentation).  To specify the JPanel to be printed by J2ComponentPrinter, you can use the J2ComponentPrinter method setComponent:
    componentPrinter.setComponent(yourComponent);
At this point componentPrinter is a Pageable (or Flowable) suitable for printing by J2Printer.

Alternatively, you can use the single-argument J2ComponentPrinter constructor:
    J2ComponentPrinter componentPrinter = new J2ComponentPrinter(yourComponent);

In addition, J2ComponentPrinter provides a convenience constructor for handling Images:
    J2ComponentPrinter imagePrinter = new J2ComponentPrinter(yourImage);
There is also a corresponding convenience method for specifying an Image:
    panelPrinter.setImage(yourImage);

The following is a simple but complete Java program (J2ComponentPrinterSimplestTest.java) that displays and prints a JPanel using J2ComponentPrinter:

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

class J2ComponentPrinterSimplestTest {
    static public void main(String args[]){
        JLabel label = new JLabel();
        label.setFont(new Font("Serif",Font.PLAIN,14));
        label.setText("<html>This is an example of <i>a JLabel</i><br>"
                    + "placed inside a <u>J2ComponentPrinter</u> and<br>"
                    + "printed using <b>J2PrinterWorks</b></html>");
        label.setPreferredSize(new Dimension(250,75);

        JFrame frame = new JFrame("J2ComponentPrinter test");
        frame.getContentPane().add(label);
        frame.pack();
        frame.setVisible(true);

        J2Printer printer = new J2Printer();
        printer.setSeparatePrintThread(false);
        J2ComponentPrinter componentPrinter = new J2ComponentPrinter(label);
        printer.addPageable(componentPrinter);
        printer.print();

        System.exit(0);
    }
}

Most of the methods of J2ComponentPrinter are set and get methods for controlling its property values. The full list of J2ComponentPrinter methods, what they do, and their default values are given in the J2ComponentPrinter Javadoc documentation .
 

General properties

Whether J2ComponentPrinter is used as a Pageable or a Flowable, you can control whether the J2ComponentPrinter operates in shrink-to-fit,, tile, break-on-components, or break-on-color mode, whether it is left, right, or center justified horizontally on a page, top, bottom, or center justified within the remaining space on a page, whether to use a white background when printing the JPanel, and whether to draw an outside line around the JPanel.

Horizontal and vertical pagination modes

J2ComponentPrinter has four modes for controlling the horizontal and vertical pagination of the JPanel to be printed, SHRINK_TO_FIT, TILE, BREAK_ON_COMPONENTS, and BREAK_ON_COLOR described above in the section J2ComponentPrinter Pagination.  To control the pagination mode of J2ComponentPrinter, use the following methods:

setHorizontalPageRule (int horizontalPageRule)
          Sets the horizontal page rule for mapping each Component into the printed page.

setVerticalPageRule (int verticalPageRule)
          Sets the vertical page rule for mapping each Component into the printed page.

Horizontal and vertical alignment

J2ComponentPrinter will print your Component 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, J2ComponentPrinter will print your Component 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 Component on the page.

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

White background

By default, J2ComponentPrinter will print your Component with the Component background color, which might be the background color of the window in which it is displayed.  You can specify whether whether the Component when printed should have a white background using the method:

setWhiteBackground (boolean whiteBackground)
          Sets whether to print the Component with a white background.
 

Outside line

J2ComponentPrinter lets you control whether to draw a line surrounding the Component and what color this line should be using the following methods:

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

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

Pageable properties

When J2ComponentPrinter 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 J2ComponentPrinter 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 J2ComponentPrinter method(s) with the argument J2Printer.GLOBAL.

The Pageable properties of J2ComponentPrinter will be ignored when the J2ComponentPrinter 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 J2ComponentPrinter used as a Flowable.  Note, however, that scaling does work for J2ComponentPrinter used as either a Pageable or a Flowable, that is, the J2ComponentPrinter 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, J2ComponentPrinter also supports fit-to-page scaling when J2ComponentPrinter is used as a Pageable using the following method:

setMaximumPages (int pagesWide, int pagesHigh)
          Set the maximum number of vertical and/or horizontal pages for printing the J2ComponentPrinter (will minify to fit).

The setMaximumPages method causes your J2PanelPrinter to be scaled down until it fits within pagesWide pages horizontally and pagesHigh pages vertically.  This method cannot be used to magnify and instead will only minify your JPanel (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 J2PanelPrinter fits within the prescribed limits.  There is only one scaling factor, which is used both horizontally and vertically, so no distortions are introduced.  If either pagesWide or pagesHigh is set to 0 or less, this is taken as a signal that the scaling in that dimension is unconstrained, that is, the J2PanelPrinter can use as many pages as it needs. 

The setMaximumPages method causes the rescaling to be calculated and set only at the time it is called and does NOT remember or maintain the page limits you specify, i.e., it is not a state property.  Thus, if you change any printing parameters including your document content, headers, footers, margins, paper size, orientation, etc., you must call setMaximumPages again.

IMPORTANT: Instead of using setMaximumPages(1,0) or setMaximumPages(1,1) to rescale your Component to one page wide and/or high, you are strongly encouraged to use SHRINK_TO_FIT pagination mode for the horizontal and/or vertical directions.  SHRINK_TO_FIT mode has the major benefit of being a direct calculation and therefore much faster than the iterative setMaximumPages.  In addition, SHRINK_TO_FIT is a state that is maintained in the presence of table and/or page size changes and once it is set up it does not need to be reinvoked.  In general, you should use setMaximumPages only if the desired number of horizontal and/or vertical pages is greater than 1.

The percentage and fit-to-page scaling features interact.  You can call setMaximumPages(pagesWide, 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(pagesWide, pagesHigh)).
 

Additional features
 

J2ComponentPrinter WYSIWYG support

J2ComponentPrinter inherently performs WYSIWYG printing since it images your Component instance directly using the Java print and paint methods.  This means you will print all of your JPanel's specified fonts, relative sizes, layout, colors, etc.  The general rule is: whatever your Component displays is what J2ComponentPrinter will print.
 

Non-GUI JPanel printing

It is not necessary that the Component 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 Component displayed but wish to print from a different non-GUI copy of the Component.  The latter situation can arise when you want to set the printing Component properties different from your on-screen Component display, such as to force different background, size, layout, or fonts as appropriate for a printed page.  In such cases, you can use code like:
 
  Component component2 = (Component) (J2Printer.clone(component1));

  component2.setSize(component2.getPreferredSize()); // size required

This code assumes your Component is serializable, since this is how we implement the clone method.  If necessary, you can implement writeObject and readObject methods for your Component in order to make it serializable.
 

Java Borders

You can use the Java Swing Borders classes to add various kinds of borders to your Component, and these will be printed by J2ComponentPrinter .  Borders work when using J2ComponentPrinter as either a Pageable or a Flowable.  You can use both the Java Borders feature and the J2ComponentPrinter method setOutsideLines(true) at the same time (the Java Border will be inside the outside line).  Some examples of Java Borders are:
    component.setBorder(new LineBorder(Color.green,20));
    component.setBorder(new EmptyBorder(10,10,10,10));
    component.setBorder(new CompoundBorder(new LineBorder(Color.green,20),new EmptyBorder(10,10,10,10)));


Using J2ComponentPrinter 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 J2ComponentPrinter, 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 J2ComponentPrinter 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 J2ComponentPrinter , using the setComponent method or the J2ComponentPrinter constructor itself to specify your Component or subclass thereof (e.g. JComponent, JPanel, JLabel, etc.).

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 )