How do I catch the error from my printer with PrintDocument?

Question

I am using the PrintDocument class to print to my Brother label printer. When I execute the Print() method, the printer starts flashing a red error light, but everything else returns successful.

I can run this same code on my laser printer and everything works fine.

How can I see what is causing the error on my label printer?

Code:

public class Test
{
    private Font printFont;
    private List<string> _documentLinesToPrint = new List<string>();

    public void Run()
    {
        _documentLinesToPrint.Add("Test1");
        _documentLinesToPrint.Add("Test2");
        printFont = new Font("Arial", 10);
        var pd = new PrintDocument();
        pd.DefaultPageSettings.Margins = new Margins(25, 25, 25, 25);
        pd.DefaultPageSettings.PaperSize = new PaperSize("Label", 400, 237);

        var printerSettings = new System.Drawing.Printing.PrinterSettings();
        printerSettings.PrinterName ="Brother QL-570 LE";
        pd.PrinterSettings = printerSettings;
        pd.PrinterSettings.Copies = 1;
        pd.PrintPage += new PrintPageEventHandler(this.pd_PrintPage);
        pd.Print();
    }

    // The PrintPage event is raised for each page to be printed. 
    private void pd_PrintPage(object sender, PrintPageEventArgs ev)
    {
        float linesPerPage = 0;
        float yPos = 0;
        int count = 0;
        float leftMargin = ev.MarginBounds.Left;
        float topMargin = ev.MarginBounds.Top;
        string line = null;

        // Calculate the number of lines per page.
        linesPerPage = ev.MarginBounds.Height /
           printFont.GetHeight(ev.Graphics);

        // Print each line of the file. 
        while ((count < linesPerPage) && (count < _documentLinesToPrint.Count))
        {
            line = _documentLinesToPrint[count];

            yPos = topMargin + (count *
               printFont.GetHeight(ev.Graphics));
            ev.Graphics.DrawString(line, printFont, Brushes.Black,
               leftMargin, yPos, new StringFormat());

            line = null;
            count++;
        }

        // If more lines exist, print another page. 
        if (line != null)
            ev.HasMorePages = true;
        else
            ev.HasMorePages = false;
    }
}

If that does not work you may have to switch to a lower level printing mechanism. And of course check the printer manual. — P.Brian.Mackey, Nov 07 '13 at 22:01
I think you may be mis-understanding. The code itself is not throwing any kind of error. The print commands are making it to the printer just fine. However, whatever print commands I'm sending to the printer are not working for some reason. How do I trap why my printer is flashing a red light? — Scottie, Nov 07 '13 at 22:04

P.Brian.Mackey · Accepted Answer · 2013-11-08T03:40:26.557

PrintDocument is a very basic API. You get simple generic printing, but it comes at the cost of reduced functionality not specific to the print driver. My HP printer usually gives me a printed error rather than an Exception. Its not surprising to see something similar happening to you.

The blinking is likely a code that you can lookup. If that fails you can try saving to an Image format, PDF or XPS. Or use a 3rd party library or write your own PCL file. There's a ton of options. Creating an output you can view as opposed to one in memory should debugging calculations like margins. You can look at a PDF and see if it looks wacky. Just keep in mind the way it looks on the PC may be slightly different than the output especially when printing near the edges.

score 3 · Answer 2 · answered Nov 08 '13 at 03:38

3

I could be completely wrong on this, but my understanding is that when you print with this code, it has nothing to do with the printer itself, but with the operating system. Windows sets up a print queue, places the output in it, and your code returns.

Then Windows takes items off of the queue and sends them through the printer driver and to your printer. If there's an error in printing, it should show up as a failed document in the print queue. I think it's too late to trap the error as an exception at this stage.

Please correct me if I am mistaken.

answered Nov 08 '13 at 03:38

Matt Johnson-Pint

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I believe the `PrintPage` event is a callback that actively fires during the physical print process. I don't have my code on this PC to verify. – P.Brian.Mackey Nov 08 '13 at 03:49
I was thinking it fired during the *spooling* process, rather then during printing itself. – Matt Johnson-Pint Nov 08 '13 at 03:50
Maybe that is the case. I suspected a level of communication with the driver because the event handler argument `PrintPageEventArgs` provides printer specific information such as margins. – P.Brian.Mackey Nov 08 '13 at 03:54
Yeah, I'm really not certain on that. Just thought I would throw it out there. – Matt Johnson-Pint Nov 08 '13 at 03:55

score 0 · Answer 3 · answered Nov 07 '13 at 22:00

I would surround your the method bodies using a Try/Catch Block then handle the exception(s) within the catch of each method. As an example:

public class Test
{
    private Font printFont;
    private List<string> _documentLinesToPrint = new List<string>();

    public void Run()
    {
        try
        {
            _documentLinesToPrint.Add("Test1");
            _documentLinesToPrint.Add("Test2");
            printFont = new Font("Arial", 10);
            var pd = new PrintDocument();
            pd.DefaultPageSettings.Margins = new Margins(25, 25, 25, 25);
            pd.DefaultPageSettings.PaperSize = new PaperSize("Label", 400, 237);

            var printerSettings = new System.Drawing.Printing.PrinterSettings();
            printerSettings.PrinterName = "Brother QL-570 LE";
            pd.PrinterSettings = printerSettings;
            pd.PrinterSettings.Copies = 1;
            pd.PrintPage += new PrintPageEventHandler(this.pd_PrintPage);
            pd.Print();
        }
        catch (InvalidPrinterException exc)
        {
            // handle your errors here.
        }

        catch (Exception ex)
        {
            // handle your errors here.
        }
    }

    // The PrintPage event is raised for each page to be printed. 
    private void pd_PrintPage(object sender, PrintPageEventArgs ev)
    {
        try
        {
            float linesPerPage = 0;
            float yPos = 0;
            int count = 0;
            float leftMargin = ev.MarginBounds.Left;
            float topMargin = ev.MarginBounds.Top;
            string line = null;

            // Calculate the number of lines per page.
            linesPerPage = ev.MarginBounds.Height /
               printFont.GetHeight(ev.Graphics);

            // Print each line of the file. 
            while ((count < linesPerPage) && (count < _documentLinesToPrint.Count))
            {
                line = _documentLinesToPrint[count];

                yPos = topMargin + (count *
                   printFont.GetHeight(ev.Graphics));
                ev.Graphics.DrawString(line, printFont, Brushes.Black,
                   leftMargin, yPos, new StringFormat());

                line = null;
                count++;
            }

            // If more lines exist, print another page. 
            if (line != null)
                ev.HasMorePages = true;
            else
                ev.HasMorePages = false;
        }
        catch (InvalidPrinterException exc)
        {
            // handle your errors here.
        }

        catch (Exception ex)
        {
            // handle your errors here.
        }
    }
}

How do I catch the error from my printer with PrintDocument?

3 Answers3