ChartPrintJob.java

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2013, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * ------------------
 * ChartPrintJob.java
 * ------------------
 * (C) Copyright 2012, by Jonas Rüttimann.
 *
 * Original Author:  Jonas Rüttimann;
 * Contributor(s):   -
 *
 * Changes
 * -------
 * 05-Jul-2012 : Version 1, from bug 2963199 (JR);
 *
 */

package org.jfree.experimental.chart.swt;

import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
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.Composite;

/**
 * Printer job for SWT.
 */
public class ChartPrintJob {

    /**
     * Border on the paper not to print on (in inches)
     */
    private static final double BORDER = 0.8;

    private String jobName;

    /**
     * Creates a new job.
     * 
     * @param jobName  this will be the name of the print job or the default 
     *     name of the file (if printed to a file).
     */
    public ChartPrintJob(String jobName) {
        this.jobName = jobName;
    }

    /** 
     * Prints the specified element.
     * 
     * @param elementToPrint  the {@link Composite} to be printed.
     */
    public void print(Composite elementToPrint) {
        PrintDialog dialog = new PrintDialog(elementToPrint.getShell());
        PrinterData printerData = dialog.open();
        if (printerData == null) {
            return; // Anwender hat abgebrochen.
        }
        startPrintJob(elementToPrint, printerData);
    }

    protected void startPrintJob(Composite elementToPrint, 
            PrinterData printerData) {
        Printer printer = new Printer(printerData);
        try {
            printer.startJob(jobName);

            GC gc = new GC(printer);
            try {
                Rectangle printArea = getPrintableArea(printer, BORDER);
                printer.startPage();
                printComposite(elementToPrint, gc, printArea);
                printer.endPage();
            } finally {
                gc.dispose();
            }
            printer.endJob();

        } finally {
            printer.dispose();
        }
    }

    /**
     * @param printer
     * @param safetyBorder
     * @return the rectangle in pixels to print on (and which is also supported
     * by the printer hardware)
     */
    private Rectangle getPrintableArea(Printer printer, double safetyBorder) {
        int safetyBorderWidth = (int) (safetyBorder * printer.getDPI().x);
        int safetyBorderHeight = (int) (safetyBorder * printer.getDPI().y);

        Rectangle trim = printer.computeTrim(0, 0, 0, 0);
        int trimLeft = -trim.x;
        int trimTop = -trim.y;
        int trimRight = trim.x + trim.width;
        int trimBottom = trim.y + trim.height;

        int marginLeft = Math.max(trimLeft, safetyBorderWidth);
        int marginRight = Math.max(trimRight, safetyBorderWidth);
        int marginTop = Math.max(trimTop, safetyBorderHeight);
        int marginBottom = Math.max(trimBottom, safetyBorderHeight);

        int availWidth = printer.getClientArea().width - marginLeft
                - marginRight;
        int availHeight = printer.getClientArea().height - marginTop
                - marginBottom;
        return new Rectangle(marginLeft, marginTop, availWidth, availHeight);
    }

    private void printComposite(Composite elementToPrint, GC gc, 
            Rectangle printArea) {
        Image image = new Image(elementToPrint.getDisplay(),
                elementToPrint.getSize().x, elementToPrint.getSize().y);
        try {
            GC imageGC = new GC(image);
            try {
                elementToPrint.print(imageGC);
                Point fittedSize = calcFittedSize(printArea, 
                        elementToPrint.getSize());
                gc.drawImage(image, 0, 0, elementToPrint.getSize().x,
                        elementToPrint.getSize().y, printArea.x, printArea.y, 
                        fittedSize.x, fittedSize.y);

            } finally {
                imageGC.dispose();
            }
        } finally {
            image.dispose();
        }
    }

    /**
     * The object to print should be scaled up or down to fit horizontally and
     * vertically the available space.
     *     
     * @param printArea
     * @param originalSize
     * 
     * @return the fitted size of the object to print
     */
    Point calcFittedSize(Rectangle printArea, Point originalSize) {
        double scaleFactor = Math.min(
                (double) printArea.height / originalSize.y,
                (double) printArea.width / originalSize.x);
        int trgHeight = (int) Math.ceil(originalSize.y * scaleFactor);
        int trgWidth = (int) Math.ceil(originalSize.x * scaleFactor);
        return new Point(trgWidth, trgHeight);
    }

}