C#查询打印机状态

近来对打印机做了一些研究，因为某些需要所以想对打印机状态进行查询，在此留下心得。

有些打印机厂家会提供专门的SDK供使用者查询打印机状态，但通常情况下，在C#中还是选择调用WIN32 api来进行打印机状态的监控。下面进入正题

调用WIN32 API 需要先声明命名空间

using System.Runtime.InteropServices;

[DllImport(\"winspool.drv\", CharSet = CharSet.Auto)]
        public static extern bool OpenPrinter(string pPrinterName, out IntPtr phPrinter, IntPtr pDefault);//打开打印机

        [DllImport(\"winspool.drv\", CharSet = CharSet.Auto)]
        public static extern bool ClosePrinter(IntPtr hPrinter);//关闭

        [DllImport(\"winspool.drv\", CharSet = CharSet.Auto)]
        public static extern int EnumJobs(IntPtr hPrinter, int FirstJob, int NoJobs, int Level, IntPtr pInfo, int cdBuf,out int pcbNeeded, out int pcReturned);//状态获取

然后是调用

                IntPtr handle;
                int FirstJob = 0;
                int NumJobs = 127;
                int pcbNeeded;
                int pcReturned;
                int test;

                bool settest=
                // open printer  
                OpenPrinter(printerToPeek, out handle, IntPtr.Zero);

                //// get num bytes required, here we assume the maxt job for the printer quest is 128 (0..127)  
                EnumJobs(handle, FirstJob, NumJobs, 1, IntPtr.Zero, 0, out pcbNeeded, out pcReturned);
                // allocate unmanaged memory  
                IntPtr pData = Marshal.AllocHGlobal(pcbNeeded);

                // get structs  
                EnumJobs(handle, FirstJob, NumJobs, 1, pData, pcbNeeded, out pcbNeeded, out pcReturned);

判断EnumJobs函数的返回或者pcbNeeded的数值可以判断打印机状态，正在就绪是0，即pcbNeeded==0?正在就绪：其他状态。其他的未进行研究。

参考：

C#打印机监控程序