java - How can I get the total number of pages to be printed?

Question

This is the basic printing program example from the Sun tutorial:

PrinterJob job = PrinterJob.getPrinterJob();
job.setPrintable(new HelloWorldPrinter());
boolean doPrint = job.printDialog();
if (doPrint) {
    try {
        job.print();
    } catch (PrinterException e) {
        /* The job did not successfully complete */
    }
}

When the user is shown the print dialog (on the second line), he can choose to print only a range of pages from the document. Can I somehow get the number of pages that are to be printed? For example, if I have a 25 page document, but the user chooses to print the range 4-10, then only 7 pages will be printed. Is there someway to access that information?

I need this in order to show a progress bar which increases with each page printed, but for that I need to know the total number of pages that are going to be printed.

So how can I get that number?

Answer 1

I've managed to find a solution.

The printDialog() method displays a native print dialog, but the printDialog(PrintRequestAttributeSet attributes) method shows a cross-platform dialog. The PrintRequestAttributeSet parameter is filled out with the user's selections, including the page range selected to be printed. Thus, after returning from the printDialog method, the page range can be queried, like in the following code sequence:

PrinterJob job = PrinterJob.getPrinterJob();
job.setPrintable(new HelloWorldPrinter());
HashPrintRequestAttributeSet printParams = new HashPrintRequestAttributeSet();
boolean ok = job.printDialog(printParams);
if (ok) {
    PageRanges pageRanges = (PageRanges) printParams.get(PageRanges.class);
    int pagesToBePrinted = getNumberOfPages(pageRanges);
    try {
        job.print(printParams);
    } catch (PrinterException e) {
        /* The job did not successfully complete */
    }
}

Note that the printParams has to be given to the print() method as well. From the PageRanges object, the page ranges can be obtained in array format, i.e. an array of 1-length arrays meaning a single page each or 2-length arrays meaning contiguous ranges of pages. See the javadoc for more details. To calculate the total number of pages is straightforward:

int getNumberOfPages(PageRanges pageRanges) {
    int pages = 0;
    int[][] ranges = pageRanges.getMembers();
    for (int i = 0; i < ranges.length; i++) {
        pages += 1;
        if (ranges[i].length == 2) {
            pages += ranges[i][1] - ranges[i][0];
        }
    }
    pages = Math.min(pages, totalPagesOfDocument);
    return pages;
}

If the user doesn't select a page range, but the 'All pages' option instead, then the PageRanges will contain the range (1, Integer.MAX_VALUE). So I say that if the computed value exceeds the number of pages of the document, then the number of pages to be printed is the total number of the document's pages (which I hope you know from somewhere).

The algorithm is perhaps overkill, as probably the PageRanges will only be a simple n - m range, but better safe than sorry.