c#-直接将字节数组发送到打印机

2019-12-09 22:08:20 阅读：652 来源： 互联网

我的服务使用以下代码将报告转换为字节数组,然后传递给客户端(wpf应用)：

byte[] bytes = renderer.ServerReport.Render("PDF", deviceInfo, out mimeType, out encoding, out extension, out streamids, out warnings);

其中renderer是Microsoft.Reporting.Webforms.ReportViewer的实例.这里有一个问题：encoding输出参数返回null,因此找不到有关编码的信息.

UI必须将此字节数组以静默方式打印到打印机.可以将此字节数组直接发送到打印机,而不是在UI中将其转换回PDF文件然后进行打印吗？

在查看msdn链接后,我实际上尝试了以下类似操作,但是当实际报告只有一页或一页时,这会在许多页面上打印出奇怪的符号.有关winspool dll的在线功能的信息较少,所以不确定我要去哪里.

任何想法高度赞赏.

public class RawPrintHelper
{
     //Structure and API declarions:
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public class DOCINFOA
    {
        [MarshalAs(UnmanagedType.LPStr)]
        public string pDocName;
        [MarshalAs(UnmanagedType.LPStr)]
        public string pOutputFile;
        [MarshalAs(UnmanagedType.LPStr)]
        public string pDataType;
    }
    [DllImport("winspool.Drv", EntryPoint = "OpenPrinter", SetLastError = true, CharSet = CharSet.Auto, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);

    [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool ClosePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "StartDocPrinter", SetLastError = true, CharSet = CharSet.Auto, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

    [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndDocPrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);

    // SendBytesToPrinter()
    // When the function is given a printer name and an unmanaged array
    // of bytes, the function sends those bytes to the print queue.
    // Returns true on success, false on failure.
    public static bool SendBytesToPrinter(string szPrinterName, IntPtr pBytes, Int32 dwCount)
    {
        Int32 dwError = 0, dwWritten = 0;
        IntPtr hPrinter = new IntPtr(0);
        DOCINFOA di = new DOCINFOA();
        bool bSuccess = false; // Assume failure unless you specifically succeed.

        di.pDocName = "My C#.NET RAW Document";
        di.pDataType = "RAW";

        // Open the printer.
        if (OpenPrinter(szPrinterName.Normalize(), out hPrinter, IntPtr.Zero))
        {
            // Start a document.
            if (StartDocPrinter(hPrinter, 1, di))
            {
                // Start a page.
                if (StartPagePrinter(hPrinter))
                {
                    // Write your bytes.
                    bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                    EndPagePrinter(hPrinter);
                }
                EndDocPrinter(hPrinter);
            }
            ClosePrinter(hPrinter);
        }
        // If you did not succeed, GetLastError may give more information
        // about why not.
        if (bSuccess == false)
        {
            dwError = Marshal.GetLastWin32Error();
        }
        return bSuccess;
    }

}

解决方法:

是的,这行不通.您使用此代码绕过打印机驱动程序,必须使用所用特定打印机的打印机控制语言来生成打印命令. PCL和Postscript是常见的打印机控制语言.但不管怎么说,制造商通常会创建自己的自定义品种.

看来您正在发送PDF,但我不知道任何使用PDF作为其本机控制语言的打印机.也许存在这样的打印机,显然您没有.我真的无法猜测为什么您会在服务中使用Webforms类,很难提供替代方法.从服务进行打印通常不是一个好主意,打印机驱动程序太高兴了,无法显示“尽快更换碳粉”提示.显示在不可见的桌面上,您无法找出为什么无法打印文档.

标签：printing,api,c
来源： https://codeday.me/bug/20191209/2097176.html

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c#-直接将字节数组发送到打印机