在C#中修改默认打印机设置（无需PrintDocument）

.NET自带的PrinterSettings类仅能读取或临时设置打印会话的参数，无法直接持久化修改打印机的全局默认配置。要实现你的需求，必须调用Windows原生Win32 API，核心逻辑是：读取当前打印机的配置结构体，修改目标参数后写回系统。

具体实现步骤与代码 #

1. 定义Win32 API依赖的结构体与函数 #

首先需要映射打印机配置相关的Win32结构体（比如PRINTER_INFO_2和DEVMODE），以及操作打印机的API函数：

using System;
using System.Runtime.InteropServices;
using System.ComponentModel;

public class PrinterDefaultConfig
{
    // 打印方向枚举
    public enum Orientation
    {
        Portrait = 1,
        Landscape = 2
    }

    // 常用纸张尺寸枚举（对应DEVMODE的dmPaperSize字段）
    public enum PaperType
    {
        Letter = 1,
        Legal = 5,
        A4 = 9,
        B5 = 13
    }

    // Win32 API函数声明
    [DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool OpenPrinter(string printerName, out IntPtr printerHandle, IntPtr defaults);

    [DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool ClosePrinter(IntPtr printerHandle);

    [DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool GetPrinter(IntPtr printerHandle, int level, IntPtr buffer, int bufferSize, out int requiredSize);

    [DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern bool SetPrinter(IntPtr printerHandle, int level, IntPtr buffer, int command);

    // 打印机详细配置结构体
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    private struct PRINTER_INFO_2
    {
        public string ServerName;
        public string PrinterName;
        public string ShareName;
        public string PortName;
        public string DriverName;
        public string Comment;
        public string Location;
        public IntPtr DevModePtr;
        public string SepFile;
        public string PrintProcessor;
        public string Datatype;
        public string Parameters;
        public IntPtr SecurityDescriptor;
        public uint Attributes;
        public uint Priority;
        public uint DefaultPriority;
        public uint StartTime;
        public uint UntilTime;
        public uint Status;
        public uint JobCount;
        public uint AveragePPM;
    }

    // 打印设备参数结构体（包含页面尺寸、方向等核心设置）
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    private struct DEVMODE
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string DeviceName;
        public ushort SpecVersion;
        public ushort DriverVersion;
        public ushort Size;
        public ushort DriverExtra;
        public uint Fields;
        public short Orientation;
        public short PaperSize;
        public short PaperLength;
        public short PaperWidth;
        public short Scale;
        public short Copies;
        public short DefaultSource;
        public short PrintQuality;
        public short Color;
        public short Duplex;
        public short YResolution;
        public short TTOption;
        public short Collate;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string FormName;
        public ushort LogPixels;
        public uint BitsPerPel;
        public uint PelsWidth;
        public uint PelsHeight;
        public uint DisplayFlags;
        public uint DisplayFrequency;
        public uint ICMMethod;
        public uint ICMIntent;
        public uint MediaType;
        public uint DitherType;
        public uint Reserved1;
        public uint Reserved2;
        public uint PanningWidth;
        public uint PanningHeight;
    }

    // DEVMODE字段修改标记常量
    private const uint DM_ORIENTATION = 0x00000001;
    private const uint DM_PAPERSIZE = 0x00000002;

2. 核心修改逻辑 #

实现方法完成"打开打印机→读取配置→修改参数→写回配置→关闭打印机"的完整流程：

public static void UpdatePrinterDefaults(string printerName, Orientation orientation, PaperType paperSize)
    {
        IntPtr printerHandle = IntPtr.Zero;
        try
        {
            // 打开目标打印机
            if (!OpenPrinter(printerName, out printerHandle, IntPtr.Zero))
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }

            // 获取配置结构体所需的缓冲区大小
            int bufferSize = 0;
            GetPrinter(printerHandle, 2, IntPtr.Zero, 0, out bufferSize);
            if (bufferSize == 0)
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }

            // 分配内存并读取打印机配置
            IntPtr configPtr = Marshal.AllocHGlobal(bufferSize);
            try
            {
                if (!GetPrinter(printerHandle, 2, configPtr, bufferSize, out bufferSize))
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }

                PRINTER_INFO_2 printerConfig = Marshal.PtrToStructure<PRINTER_INFO_2>(configPtr);
                if (printerConfig.DevModePtr == IntPtr.Zero)
                {
                    throw new InvalidOperationException("无法获取打印机的设备配置");
                }

                // 解析并修改DEVMODE参数
                DEVMODE devMode = Marshal.PtrToStructure<DEVMODE>(printerConfig.DevModePtr);
                devMode.Orientation = (short)orientation;
                devMode.Fields |= DM_ORIENTATION;

                devMode.PaperSize = (short)paperSize;
                devMode.Fields |= DM_PAPERSIZE;

                // 将修改后的参数写回内存
                Marshal.StructureToPtr(devMode, printerConfig.DevModePtr, false);
                // 将修改后的配置写回打印机
                if (!SetPrinter(printerHandle, 2, configPtr, 0))
                {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            finally
            {
                Marshal.FreeHGlobal(configPtr);
            }
        }
        finally
        {
            if (printerHandle != IntPtr.Zero)
            {
                ClosePrinter(printerHandle);
            }
        }
    }
}

3. 使用示例 #

直接调用方法即可修改指定打印机的默认设置：

// 示例：将"EPSON L3150 Series"打印机默认设置为横向、A4纸
PrinterDefaultConfig.UpdatePrinterDefaults(
    "EPSON L3150 Series",
    PrinterDefaultConfig.Orientation.Landscape,
    PrinterDefaultConfig.PaperType.A4
);

关键注意事项 #

• 权限要求：修改打印机默认配置需要管理员权限，否则SetPrinter会调用失败。
• 兼容性：部分打印机可能支持自定义纸张尺寸，此时需要修改DEVMODE的dmFormName字段并指定对应表单。
• 错误处理：代码中已加入Win32异常捕获，实际使用时可根据业务需求调整异常处理逻辑。

内容的提问来源于stack exchange，提问作者mrt