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;
    }
}

Answer 1

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.