using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace Printers
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            InitprinterComboBox(); //初始化打印机下拉列表选项
        }
        private void InitprinterComboBox()
        {
            List<String> list = LocalPrinter.GetLocalPrinters(); //获得系统中的打印机列表
            foreach (String s in list)
            {
                printerComboBox.Items.Add(s); //将打印机名称添加到下拉框中
            }
        }
        private void printButton_Click(object sender, RoutedEventArgs e)
        {
            if (printerComboBox.selectedItem != null) //判断是否有选中值
            {
                if (Externs.SetDefaultPrinter(printerComboBox.selectedItem.ToString())) //设置默认打印机
                {
                    MessageBox.Show(printerComboBox.selectedItem.ToString() + "设置为默认打印机成功！");
                }
                else
                {
                    MessageBox.Show(printerComboBox.selectedItem.ToString() + "设置为默认打印机失败！");
                }
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing.Printing;
using System.Runtime.InteropServices;
namespace Printers
{
    class LocalPrinter
    {
        private static PrintDocument fPrintDocument = new PrintDocument();
        //获取本机默认打印机名称
        public static String DefaultPrinter()
        {
            return fPrintDocument.PrinterSettings.PrinterName;
        }
        public static List<String> GetLocalPrinters()
        {
            List<String> fPrinters = new List<String>();
            fPrinters.Add(DefaultPrinter()); //默认打印机始终出现在列表的第一项
            foreach (String fPrinterName in PrinterSettings.InstalledPrinters)
            {
                if (!fPrinters.Contains(fPrinterName))
                {
                    fPrinters.Add(fPrinterName);
                }
            }
            return fPrinters;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
namespace Printers
{
    class Externs
    {
        [DllImport("winspool.drv")]
        public static extern bool SetDefaultPrinter(String Name); //调用win api将指定名称的打印机设置为默认打印机
    }
}