我有一些用于执行打印机功能的C#代码(VS2010; fx2)。此代码在Windows XP环境中正常工作。更改为Windows 7,它不再正常工作。
第一个不同的行为是GetPrinterNames()方法现在只返回本地打印机。如您所见,标志也设置为包括NETWORK打印机。我尝试过不同的旗帜,但没有成功。
我应该在Windows 7/64位版本中引用不同的库吗?
打印机助手类,代码如下所示:
internal class Printers
{
...
[DllImport("winspool.drv", SetLastError = true)]
static extern bool EnumPrintersW(Int32 flags, [MarshalAs(UnmanagedType.LPTStr)] string printerName,
Int32 level, IntPtr buffer, Int32 bufferSize, out Int32 requiredBufferSize,
out Int32 numPrintersReturned);
[DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool EnumPrinters(PrinterEnumFlags Flags, string Name, uint Level, IntPtr pPrinterEnum, uint cbBuf, ref uint pcbNeeded, ref uint pcReturned);
...
...
public static string[] GetPrinterNames()
{
List<string> returnVal = new List<string>();
foreach(PRINTER_INFO_2 info in enumPrinters(PrinterEnumFlags.PRINTER_ENUM_LOCAL | PrinterEnumFlags.PRINTER_ENUM_NETWORK))
{
returnVal.Add(info.pPrinterName);
}
return returnVal.ToArray();
}
...
private static PRINTER_INFO_2[] enumPrinters(PrinterEnumFlags Flags)
{
uint cbNeeded = 0;
uint cReturned = 0;
if (EnumPrinters(Flags, null, 2, IntPtr.Zero, 0, ref cbNeeded, ref cReturned))
{
return null;
}
int lastWin32Error = Marshal.GetLastWin32Error();
if (lastWin32Error == ERROR_INSUFFICIENT_BUFFER)
{
IntPtr pAddr = Marshal.AllocHGlobal((int)cbNeeded);
if (EnumPrinters(Flags, null, 2, pAddr, cbNeeded, ref cbNeeded, ref cReturned))
{
PRINTER_INFO_2[] printerInfo2 = new PRINTER_INFO_2[cReturned];
int offset = pAddr.ToInt32();
Type type = typeof(PRINTER_INFO_2);
int increment = Marshal.SizeOf(type);
for (int i = 0; i < cReturned; i++)
{
printerInfo2[i] = (PRINTER_INFO_2)Marshal.PtrToStructure(new IntPtr(offset), type);
offset += increment;
}
Marshal.FreeHGlobal(pAddr);
return printerInfo2;
}
lastWin32Error = Marshal.GetLastWin32Error();
}
throw new System.ComponentModel.Win32Exception(lastWin32Error);
}
...
[FlagsAttribute]
enum PrinterEnumFlags
{
PRINTER_ENUM_DEFAULT = 0x00000001,
PRINTER_ENUM_LOCAL = 0x00000002,
PRINTER_ENUM_CONNECTIONS = 0x00000004,
PRINTER_ENUM_FAVORITE = 0x00000004,
PRINTER_ENUM_NAME = 0x00000008,
PRINTER_ENUM_REMOTE = 0x00000010,
PRINTER_ENUM_SHARED = 0x00000020,
PRINTER_ENUM_NETWORK = 0x00000040,
PRINTER_ENUM_EXPAND = 0x00004000,
PRINTER_ENUM_CONTAINER = 0x00008000,
PRINTER_ENUM_ICONMASK = 0x00ff0000,
PRINTER_ENUM_ICON1 = 0x00010000,
PRINTER_ENUM_ICON2 = 0x00020000,
PRINTER_ENUM_ICON3 = 0x00040000,
PRINTER_ENUM_ICON4 = 0x00080000,
PRINTER_ENUM_ICON5 = 0x00100000,
PRINTER_ENUM_ICON6 = 0x00200000,
PRINTER_ENUM_ICON7 = 0x00400000,
PRINTER_ENUM_ICON8 = 0x00800000,
PRINTER_ENUM_HIDE = 0x01000000
}
编辑:编辑代码以减小尺寸(删除不太感兴趣的区域)。
答案 0 :(得分:1)
根据EndnPrinters的msdn说明,您的代码仅在第3个参数为1时才有效
来自EnumPrinters的....
PRINTER_ENUM_NETWORK 该功能枚举计算机域中的网络打印机。仅当Level为1时,此值才有效。
答案 1 :(得分:1)
在64位Windows机器上是OverflowException
的异常(算术运算导致溢出。)由一个32位整数而不是64位整数转换指针引起。
int offset = pAddr.ToInt32();
用
修复它long offset = pAddr.ToInt64();
完整的工作代码,在Windows 10 x64上检查
public static string[] GetPrinterNames()
{
var results = new List<string>();
foreach (PRINTER_INFO_2 info in enumPrinters(PrinterEnumFlags.PRINTER_ENUM_LOCAL | PrinterEnumFlags.PRINTER_ENUM_NETWORK))
results.Add(info.pPrinterName);
return results.ToArray();
}
private static PRINTER_INFO_2[] enumPrinters(PrinterEnumFlags Flags)
{
uint cbNeeded = 0;
uint cReturned = 0;
if (EnumPrinters(Flags, null, 2, IntPtr.Zero, 0, ref cbNeeded, ref cReturned))
{
return null;
}
int lastWin32Error = Marshal.GetLastWin32Error();
if (lastWin32Error == ERROR_INSUFFICIENT_BUFFER)
{
IntPtr pAddr = Marshal.AllocHGlobal((int)cbNeeded);
if (EnumPrinters(Flags, null, 2, pAddr, cbNeeded, ref cbNeeded, ref cReturned))
{
PRINTER_INFO_2[] printerInfo2 = new PRINTER_INFO_2[cReturned];
long offset = pAddr.ToInt64();
Type type = typeof(PRINTER_INFO_2);
int increment = Marshal.SizeOf(type);
for (int i = 0; i < cReturned; i++)
{
printerInfo2[i] = (PRINTER_INFO_2)Marshal.PtrToStructure(new IntPtr(offset), type);
offset += increment;
}
Marshal.FreeHGlobal(pAddr);
return printerInfo2;
}
lastWin32Error = Marshal.GetLastWin32Error();
}
throw new System.ComponentModel.Win32Exception(lastWin32Error);
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
internal struct PRINTER_INFO_2
{
[MarshalAs(UnmanagedType.LPTStr)]
public string pServerName;
[MarshalAs(UnmanagedType.LPTStr)]
public string pPrinterName;
[MarshalAs(UnmanagedType.LPTStr)]
public string pShareName;
[MarshalAs(UnmanagedType.LPTStr)]
public string pPortName;
[MarshalAs(UnmanagedType.LPTStr)]
public string pDriverName;
[MarshalAs(UnmanagedType.LPTStr)]
public string pComment;
[MarshalAs(UnmanagedType.LPTStr)]
public string pLocation;
public IntPtr pDevMode;
[MarshalAs(UnmanagedType.LPTStr)]
public string pSepFile;
[MarshalAs(UnmanagedType.LPTStr)]
public string pPrintProcessor;
[MarshalAs(UnmanagedType.LPTStr)]
public string pDatatype;
[MarshalAs(UnmanagedType.LPTStr)]
public string pParameters;
public IntPtr pSecurityDescriptor;
public uint Attributes;
public uint Priority;
public uint DefaultPriority;
public uint StartTime;
public uint UntilTime;
public uint Status;
public uint cJobs;
public uint AveragePPM;
}
const int ERROR_INSUFFICIENT_BUFFER = 122;
[FlagsAttribute]
enum PrinterEnumFlags
{
PRINTER_ENUM_DEFAULT = 0x00000001,
PRINTER_ENUM_LOCAL = 0x00000002,
PRINTER_ENUM_CONNECTIONS = 0x00000004,
PRINTER_ENUM_FAVORITE = 0x00000004,
PRINTER_ENUM_NAME = 0x00000008,
PRINTER_ENUM_REMOTE = 0x00000010,
PRINTER_ENUM_SHARED = 0x00000020,
PRINTER_ENUM_NETWORK = 0x00000040,
PRINTER_ENUM_EXPAND = 0x00004000,
PRINTER_ENUM_CONTAINER = 0x00008000,
PRINTER_ENUM_ICONMASK = 0x00ff0000,
PRINTER_ENUM_ICON1 = 0x00010000,
PRINTER_ENUM_ICON2 = 0x00020000,
PRINTER_ENUM_ICON3 = 0x00040000,
PRINTER_ENUM_ICON4 = 0x00080000,
PRINTER_ENUM_ICON5 = 0x00100000,
PRINTER_ENUM_ICON6 = 0x00200000,
PRINTER_ENUM_ICON7 = 0x00400000,
PRINTER_ENUM_ICON8 = 0x00800000,
PRINTER_ENUM_HIDE = 0x01000000
}
[DllImport("winspool.drv", SetLastError = true)]
static extern bool EnumPrintersW(Int32 flags, [MarshalAs(UnmanagedType.LPTStr)] string printerName,
Int32 level, IntPtr buffer, Int32 bufferSize, out Int32 requiredBufferSize,
out Int32 numPrintersReturned);
[DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool EnumPrinters(PrinterEnumFlags Flags, string Name, uint Level, IntPtr pPrinterEnum, uint cbBuf, ref uint pcbNeeded, ref uint pcReturned);