Java InstantCode. Developing Applications Using Java NIO

The PrintComp.java file implements the Printable interface of Java. This file allows an end user to print a document through the network printer.

Listing 5-2 shows the contents of the PrintComp.java file:

Listing 5-2: The PrintComp.java File

/* Imports required awt classes. */ import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.print.Printable; import java.awt.print.PrinterException; import java.awt.print.PrinterJob; import java.awt.print.PageFormat; /* Imports required swing classes. */ import javax.swing.JComponent; /* class PrintComp - This class is the subclass of the application. This class implements the Printable interface and prints a component. Methods: printComponent() - Invokes the print() method of PrintComp class and prints a component. pageSetupAndPrint() - Allows the end user to specify the page setup and print the page. print() - Prints the page. print()-Prints a graphic at the specified page index in the specified page format. */ class PrintComp implements Printable { /* Declares object of the JComponent class.*/ private JComponent component; /* Declares object of the PrinterJob class.*/ PrinterJob printJob = PrinterJob.getPrinterJob(); /* Declares object of the PageFormat class*/ PageFormat pageFormat= printJob.defaultPage(); /* printComponent - This method is called when the end user clicks the Print Default menu item in the user interface of PrintFile. Parameters: c - An object of the JComponent class. Return Value: NA */ public static void printComponent(JComponent c) { new PrintComp(c).print(); } /* Implements the constructor of the PrintComp class. */ public PrintComp(JComponent component) { this.component= component; } /* pageSetupAndPrint - This method is called when the end user clicks the Page Setup and Print button. Parameters: NA Return Value: NA */ public void pageSetupAndPrint() { /* Initializes the object of the PageFormat class. */ pageFormat = printJob.pageDialog(pageFormat); /* Sets the object of the PrinterJob class to printable. */ printJob.setPrintable(this, pageFormat); if (printJob.printDialog()) { try { /* Prints the document. */ printJob.print(); } catch(PrinterException pe) { System.out.println("Error in printing !!! " + pe); } } } /* print - This method is called when the end user clicks the Print button. Parameters: NA Return Value: NA */ public void print() { /* Sets the object of the PrinterJob class to printable. */ printJob.setPrintable(this, pageFormat); /* Checks the return value of PrintDialog. */ if (printJob.printDialog()) { try { /* Prints the document. */ printJob.print(); } catch(PrinterException pe) { System.out.println("Error in printing !!! " + pe); } } } /* print() - This method defines a Printable interface. Parameters: g - Represents the object of the Graphics class. pf - Represents the object of the PageFormat class. index - Represents an index of the page. Return Value: int PAGE_EXIST */ public int print(Graphics g, PageFormat pf, int pageIndex) throws PrinterException { /* Creates an object of the Graphics2D class and convert simple graphics to 2D graphics. */ Graphics2D g2 = (Graphics2D)g; /*Gets size of document. */ Dimension d = component.getSize(); /* Gets the width of document in pixels. */ double componentWidth = d.width; /* Gets the height of document in pixels. */ double componentHeight = d.height; /* Gets the height of printer page. */ double pageHeight = pf.getImageableHeight(); /* Get the width of printer page*/ double pageWidth = pf.getImageableWidth(); /* Sets the value of scale for the document to be printed. */ double scale = pageWidth/componentWidth; int pages = (int)Math.ceil(scale * componentHeight / pageHeight); /* Does not print empty pages. */ if(pageIndex >= pages) { return Printable.NO_SUCH_PAGE; } /* Shifts the graphic to line up with the beginning of print-imageable region. */ g2.translate(pf.getImageableX(), pf.getImageableY()); /* Shifts the graphic to line up with the beginning of the next page to print. */ g2.translate(0f, -pageIndex*pageHeight); /* Scales the page so that the width fits. */ g2.scale(scale, scale); /* Repaints the page. */ component.paint(g2); return Printable.PAGE_EXISTS; } }

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In the above code, the constructor of the PrintComp class uses the object of the JComponent class to load the text or image file. The methods defined in the listing are:

• printComponent() : Calls the print() method to print the document.

• pageSetupAndPrint() : Initializes the object of the PageFormat class and sets the object of the PrinterJob class to printable. This method then calls the print() method of the PrinterJob class.

• print() : Calls the print() method of the PrinterJob class.

• print(Graphics g, PageFormat pf, int pageIndex) : Creates an object of the Graphics2D class and converts simple graphics to 2D ones. This method then gets the size of the document and sets its scale value. Next, the method calls the translate() and scale() methods of the Graphics2D class. Finally, the print() method calls the paint() method of the Component class to paint the document with new dimensions and returns Printable.PAGE_EXISTS.