JMSL Chart Guide: Printing

JMSL Chart Programmer's Guide

Actions >> Printing

Printing

Printing from JFrameChart

The JFrameChart class, used to build most of the examples in this manual, includes a print option under the file menu. This option prints the chart as large as possible, without distortion, and centered on the page.

Printable Interface

The Java Printable interface is used to print a single page from Java. It is implemented by the class Chart. The following code fragment shows how to print a chart using its Printable interface and PrinterJob.

public void print() {
        PrinterJob printJob = PrinterJob.getPrinterJob();
        printJob.setPrintable(chart);
        if (printJob.printDialog()) {
            try {
                printJob.print();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }

The PrinterJob.printDialog() method displays a dialog box that may contain a "Property Sheet." This property sheet is supplied by the hardware printer driver, not by Java. User changes to property sheet values are not reflected back to Java. Specifically, while a property sheet may allow the user to select landscape or portrait mode, these settings are not reflected back to the PrinterJob object. The correct way to set the orientation is by using the PrinterJob.pageDialog(PageFormat) method. For more details see bug report 4311283 on Sun's Java site.

Pageable

The Java Pageable interface is used to print a complex document from Java. The method Chart.paintChart(Graphics) can be used to implement a Pageable interface. The following method is the implementation of the Printable interface in Chart. It uses the method Chart.paintChart(Graphics).

Note that the chart is drawn to fit the Component associated with the chart. The getScreenSize method returns the size of this component. The following method scales the drawing to compensate for the difference in size between the screen and the paper.

        public int print(Graphics graphics, PageFormat pageFormat, 
                         int param)
             throws PrinterException {
        if (param >= 1)  return Printable.NO_SUCH_PAGE;
        
        // translate, so we do not clip on the left
        // scale to fill the page

        graphics.translate((int)pageFormat.getImageableX(),
             (int)pageFormat.getImageableY());
        
        // scale to fill the page        
        double dw = pageFormat.getImageableWidth();
        double dh = pageFormat.getImageableHeight();
        Dimension screenSize = getScreenSize();
        double xScale = dw / screenSize.width;
        double yScale = dh / screenSize.height;
        double scale = Math.min(xScale,yScale);

        // center the chart on the page
        double tx = 0.0;
        double ty = 0.0;
        if (xScale > scale) {
            tx = 0.5*(xScale-scale)*screenSize.width;
        } else {
            ty = 0.5*(yScale-scale)*screenSize.height;
        }
        ((Graphics2D)graphics).translate(tx, ty);
        ((Graphics2D)graphics).scale(scale, scale);

        Dimension bounds = new Dimension((int)dw,(int)dh);
        paint(new Draw(graphics,bounds));
        return Printable.PAGE_EXISTS;
    }