【Silverlight5矢量打印】如何用C#代码检测打印机和驱动是否支持PostScript

Silverlight5支持PostScript矢量打印，矢量打印相比于位图打印速度更快，生成的打印文件更小。SL5默认会采用PS矢量打印，如果打印机不支持，自动切换到位图打印。

虽然微软SL打印组认为PS已经相当普遍，但我想大多数打印机估计并未安装支持PostScript的驱动。HP打印机默认的会是PCL的，估计微软选用PS是学Flash：）

如何用代码检测打印机是否支持PostScript呢？代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Runtime.InteropServices;

namespace PrinterSupportPS
{
    class Program
    {
        static void Main(string[] args)
        {
            string printerName = "Microsoft XPS Document Writer";
            Console.WriteLine(PrinterSupportsPostScript(printerName));
            Console.Read();
        }

        static Int32 GETTECHNOLOGY = 20;
        static Int32 QUERYESCSUPPORT = 8;
        static Int32 POSTSCRIPT_PASSTHROUGH = 4115;
        static Int32 ENCAPSULATED_POSTSCRIPT = 4116;

        static Int32 POSTSCRIPT_IDENTIFY = 4117;
        static Int32 POSTSCRIPT_INJECTION = 4118;
        static Int32 POSTSCRIPT_DATA = 37;
        static Int32 POSTSCRIPT_IGNORE = 38;
        [DllImport("gdi32.dll")]
        static extern int ExtEscape(IntPtr hdc, int nEscape, int cbInput,
           IntPtr lpszInData, int cbOutput, IntPtr lpszOutData);
        [DllImport("gdi32.dll")]
        static extern IntPtr CreateDC(string lpszDriver, string lpszDevice,
           IntPtr lpszOutput, IntPtr lpInitData);
        [DllImport("gdi32.dll")]
        static extern bool DeleteDC(IntPtr hdc);

        static bool PrinterSupportsPostScript(string printername)
        {
            ArrayList PSChecks = new ArrayList();
            PSChecks.Add(POSTSCRIPT_PASSTHROUGH);
            PSChecks.Add(ENCAPSULATED_POSTSCRIPT);
            PSChecks.Add(POSTSCRIPT_IDENTIFY);
            PSChecks.Add(POSTSCRIPT_INJECTION);
            PSChecks.Add(POSTSCRIPT_DATA);
            PSChecks.Add(POSTSCRIPT_IGNORE);

            IntPtr hDC = IntPtr.Zero; ;
            IntPtr BLOB = IntPtr.Zero;

            try
            {
                hDC = CreateDC(null, printername, IntPtr.Zero, IntPtr.Zero);

                int isz = 4;
                BLOB = Marshal.AllocCoTaskMem(isz);
                Marshal.WriteInt32(BLOB, GETTECHNOLOGY);

                int test = ExtEscape(hDC, QUERYESCSUPPORT, 4, BLOB, 0, IntPtr.Zero);
                if (test == 0) return false; // printer driver does not support GETTECHNOLOGY Checks.

                foreach (Int32 val in PSChecks)
                {
                    Marshal.WriteInt32(BLOB, val);
                    test = ExtEscape(hDC, QUERYESCSUPPORT, isz, BLOB, 0, IntPtr.Zero);
                    if (test != 0) return true; // if any of the checks pass, return true
                }
            }
            catch (Exception ex) { Console.WriteLine(ex); }
            finally
            {
                if (hDC != IntPtr.Zero) DeleteDC(hDC);

                if (BLOB != IntPtr.Zero) Marshal.Release(BLOB);
            };

            return false;

        }

    }
}

大家可以建一个控制台程序，用这段代码检测一下。