Question

我正在使用PrintDocument类打印到Brother标签打印机。当我执行Print（）方法时，打印机开始闪烁红色错误指示灯，但其他所有内容都返回成功。

我可以在激光打印机上运行相同的代码，一切正常。

如何在标签打印机上查看导致错误的原因？

代码：

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

我可能完全错了，但我的理解是，当您使用此代码进行打印时，它与打印机本身无关，而是与操作系统无关。 Windows设置打印队列，将输出放在其中，然后返回代码。

然后Windows将项目从队列中取出并通过打印机驱动程序和打印机发送。如果打印出错，则应在打印队列中显示为失败文档。我认为现阶段将错误视为例外是为时已晚。

如果我弄错了，请纠正我。

Answer 2

PrintDocument是一个非常基本的API。您可以获得简单的通用打印，但这是以降低打印驱动程序特有的功能为代价的。我的惠普打印机通常会给我一个打印错误而不是异常。看到类似的事情发生在你身上并不奇怪。

闪烁可能是您可以查找的代码。如果失败，您可以尝试保存为图像格式，PDF或XPS。或者使用第三方库或编写自己的PCL file。有很多选择。创建一个可以查看而不是内存中的输出的输出应该调试像边距这样的计算。您可以查看PDF并查看它是否看起来很古怪。请记住，它在PC上的外观可能与输出略有不同，尤其是在边缘附近打印时。

Answer 3

我会使用Try/Catch Block包围方法体，然后处理每种方法的catch内的异常。举个例子：

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.
        }
    }
}

如何使用PrintDocument从打印机中捕获错误？

3 个答案: