Printing HTML with Java Printing Service(JDK1.4 beta)

Question

Hi there!
I'm currently checking out the new Java Printing Service (JPS) in the new JDK1.4 beta. This looks like a very promising printing API, with amongst others printer discovery and support for MIME types - but I have some problems with printing HTML displayed in a JEditorPane.
I'm developing an application that should let the user edit a (HTML)document displayed in a JEditorPane and the print this document to a printer. I have understood that this should be peace-of-cake using the JPS which has pre-defined HTML DocFlavor amongst others, in fact here is what Eric Armstrong says on Javaworld (http://www.javaworld.com/javaone01/j1-01-coolapis.html):
"With JPS, data formats are specified using MIME types, for example: image/jpeg, text/plain, and text/html. Even better, the API includes a formatting engine that understands HTML, and an engine that, given a document that implements the Printable or Pageable interface, generates PostScript. The HTML formatting engine looks particularly valuable given the prevalence of XML data storage. You only need to set up an XSLT (eXtensible Stylesheet Language Transformation) stylesheet, use it to convert the XML data to HTML, and send the result to the printer."
After one week of reasearch I have not been able to do what Armstrong describes; print a String that contains text of MIME type text/html.
I have checked the supported MIMI types of the Print Service returned by PrintServiceLookup.lookupDefaultPrintService(). This is the result:
DocFlavor flavor = DocFlavor.INPUT_STREAM.GIF;
PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
aset.add(MediaSizeName.ISO_A4);
aset.add(new Copies(2));
PrintService[] service = PrintServiceLookup.lookupPrintServices(flavor,aset);
if (service.length > 0) {
System.out.println("Selected printer " + service[0].getName());
DocFlavor[] flavors = service[0].getSupportedDocFlavors();
for (int i = 0;i<flavors.length;i++) {
System.out.println("Flavor "+i+": "+flavors.toString());
Selected printer \\MUNIN-SERVER\HP LaserJet 2100 Series PCL 6
Flavor 0: image/gif; class="[B"
Flavor 1: image/gif; class="java.io.InputStream"
Flavor 2: image/gif; class="java.net.URL"
Flavor 3: image/jpeg; class="[B"
Flavor 4: image/jpeg; class="java.io.InputStream"
Flavor 5: image/jpeg; class="java.net.URL"
Flavor 6: image/png; class="[B"
Flavor 7: image/png; class="java.io.InputStream"
Flavor 8: image/png; class="java.net.URL"
Flavor 9: application/x-java-jvm-local-objectref; class="java.awt.print.Pageable"
Flavor 10: application/x-java-jvm-local-objectref; class="java.awt.print.Printable"
As you can see there is no support for text/html here.
If anyone has a clue to what I'm missing here or any other (elegant, simple) way to print the contents of a JEditorPane, please speak up!
Reply to: [email protected] or [email protected] or here in this forum

Answer 1

Since you have 'printable' as one of your flavors, try this using a JTextPane (assuming you can dump your HTML into a JTextPane, which shouldn't be a big problem)...
1. Have your JTextPane implement Printable
ie. something like this:
public class FormattedDocument extends JTextPane implements Printable 2. Read your HTML into the associated doc in the text pane.
3. Implement the printable interface, since you have it as one of your available flavors (I'd imagine everybody has printable in their available flavors). Something like this:
public int print(Graphics g, PageFormat pf, int pageIndex) {
        Graphics2D g2 = (Graphics2D) g;
        g2.translate((int)pf.getImageableX(), (int)pf.getImageableY());
        g2.setClip(0, 0, (int)pf.getImageableWidth(), (int)pf.getImageableHeight()); 
        if (pageIndex == 0)
            setupPrintView(pf);
        if (!pv.paintPage(g2, pageIndex))
            return NO_SUCH_PAGE;
        return PAGE_EXISTS;
    }Here's my setupPrintView function, which is executed once on page 0 (which still needs some polishing in case I want to start from page 5). It sets up a 'print view' class based on the root view of the document. PrintView class follows...
public void setupPrintView(PageFormat pf) {
View root = this.getUI().getRootView(this);
        pv = new PrintView(this.getStyledDocument().getDefaultRootElement(), root,
                           (int)pf.getImageableWidth(), (int)pf.getImageableHeight());Note of obvious: 'pv' is of type PrintView.
Here's my PrintView class that paints your text pane line by line, a page at a time, until there is no more.
class PrintView extends BoxView
    public PrintView(Element elem, View root, int w, int h) {
        super(elem, Y_AXIS);
        setParent(root);
        setSize(w, h);
        layout(w, h);
    public boolean paintPage(Graphics2D g2, int pageIndex) {
        int viewIndex = getTopOfViewIndex(pageIndex);
        if (viewIndex == -1) return false;
        int maxY = getHeight();
        Rectangle rc = new Rectangle();
        int fillCounter = 0;
        int Ytotal = 0;
        for (int k = viewIndex; k < getViewCount(); k++) {
            rc.x = 0;
            rc.y = Ytotal;
            rc.width = getSpan(X_AXIS, k);
            rc.height = getSpan(Y_AXIS, k);
            if (Ytotal + getSpan(Y_AXIS, k) > maxY) break;
            paintChild(g2, rc, k);
            Ytotal += getSpan(Y_AXIS, k);
        return true;
// find top of page for a given page number
    private int getTopOfViewIndex(int pageNumber) {
        int pageHeight = getHeight() * pageNumber;
        for (int k = 0; k < getViewCount(); k++)
            if (getOffset(Y_AXIS, k) >= pageHeight) return k;
        return -1;
}That's my 2 cents. Any questions?