Printing Text : Print « SWT « Java Tutorial

1. Java Tutorial
2. SWT
3. Print

1. Use GC.drawString() or GC.drawText() to print text.
2. wrap text on word boundaries to fit the target printer and page.

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.printing.PrintDialog;
import org.eclipse.swt.printing.Printer;
import org.eclipse.swt.printing.PrinterData;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.widgets.Shell;

public class MainClass {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);

    PrintDialog dialog = new PrintDialog(shell);
    PrinterData printerData = dialog.open();
    if (printerData != null) {
      // Create the printer
      Printer printer = new Printer(printerData);

      try {
        // Print the contents of the file
        new WrappingPrinter(printer).print();
      } catch (Exception e) {
        MessageBox mb = new MessageBox(shell, SWT.ICON_ERROR | SWT.OK);
        mb.setMessage(e.getMessage());
        mb.open();
      }

      // Dispose the printer
      printer.dispose();
    }

    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}

/**
 * This class performs the printing, wrapping text as necessary Code revised
 * from /* The Definitive Guide to SWT and JFace by Robert Harris and Rob Warner
 * Apress 2004
 */

class WrappingPrinter {
  private Printer printer; // The printer

  private String fileName; // The name of the file to print

  private String contents; // The contents of the file to print

  private GC gc; // The GC to print on

  private int xPos, yPos; // The current x and y locations for print

  private Rectangle bounds; // The boundaries for the print

  private StringBuffer buf; // Holds a word at a time

  private int lineHeight; // The height of a line of text

  /**
   * WrappingPrinter constructor
   * 
   * @param printer
   *          the printer
   * @param fileName
   *          the fileName
   * @param contents
   *          the contents
   */
  WrappingPrinter(Printer printer) {
    this.printer = printer;
    this.fileName = "yourfilename.txt";
    this.contents = "long content to wrap";
  }

  /**
   * Prints the file
   */
  void print() {
    // Start the print job
    if (printer.startJob(fileName)) {
      // Determine print area, with margins
      bounds = computePrintArea(printer);
      xPos = bounds.x;
      yPos = bounds.y;

      // Create the GC
      gc = new GC(printer);

      // Determine line height
      lineHeight = gc.getFontMetrics().getHeight();

      // Determine tab width--use three spaces for tabs
      int tabWidth = gc.stringExtent(" ").x;

      // Print the text
      printer.startPage();
      buf = new StringBuffer();
      char c;
      for (int i = 0, n = contents.length(); i < n; i++) {
        // Get the next character
        c = contents.charAt(i);

        // Check for newline
        if (c == '\n') {
          printBuffer();
          printNewline();
        }
        // Check for tab
        else if (c == '\t') {
          xPos += tabWidth;
        } else {
          buf.append(c);
          // Check for space
          if (Character.isWhitespace(c)) {
            printBuffer();
          }
        }
      }
      printer.endPage();
      printer.endJob();
      gc.dispose();
    }
  }

  /**
   * Prints the contents of the buffer
   */
  void printBuffer() {
    // Get the width of the rendered buffer
    int width = gc.stringExtent(buf.toString()).x;

    // Determine if it fits
    if (xPos + width > bounds.x + bounds.width) {
      // Doesn't fit--wrap
      printNewline();
    }

    // Print the buffer
    gc.drawString(buf.toString(), xPos, yPos, false);
    xPos += width;
    buf.setLength(0);
  }

  /**
   * Prints a newline
   */
  void printNewline() {
    // Reset x and y locations to next line
    xPos = bounds.x;
    yPos += lineHeight;

    // Have we gone to the next page?
    if (yPos > bounds.y + bounds.height) {
      yPos = bounds.y;
      printer.endPage();
      printer.startPage();
    }
  }

  /**
   * Computes the print area, including margins
   * 
   * @param printer
   *          the printer
   * @return Rectangle
   */
  Rectangle computePrintArea(Printer printer) {
    // Get the printable area
    Rectangle rect = printer.getClientArea();
    // Compute the trim
    Rectangle trim = printer.computeTrim(0, 0, 0, 0);

    // Get the printer's DPI
    Point dpi = printer.getDPI();

    // Calculate the printable area, using 1 inch margins
    int left = trim.x + dpi.x;
    if (left < rect.x)
      left = rect.x;
    int right = (rect.width + trim.x + trim.width) - dpi.x;
    if (right > rect.width)
      right = rect.width;

    int top = trim.y + dpi.y;
    if (top < rect.y)
      top = rect.y;
    int bottom = (rect.height + trim.y + trim.height) - dpi.y;
    if (bottom > rect.height)
      bottom = rect.height;

    return new Rectangle(left, top, right - left, bottom - top);
  }
}