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converting c++ API struct to c#

I am trying to convert c++ api example to c#. but I can not find the way of struct pointer in struct by the way struct has string types. Here is c++ structs and functions
struct AuthParam { char server_ip[32]; char username[50]; char password[50]; };
struct CameraInfo { int index; char devicename[100]; char smallrtsp[1000]; char bigrtsp[1000]; };
struct SingleDevice { char deviceid[50]; char devicename[100]; int flag_onuse; int cameralist_size; CameraInfo* cameralist; };
struct DeviceList { int listsize; SingleDevice* singledevicelist; };
typedef int (WINAPI capi_init)(void);
typedef int (WINAPI capi_disabled)(void);
typedef int (WINAPI capi_GetServerTimeCode)(char* server_ip, unsigned int* timecode);
typedef int (WINAPI GetDevicelist)(AuthParam auth_para, DeviceList* devicelist);
and this is my c# code but I can not find the way of defining struct pointer in struct I got "
Error CS0208 Cannot take the address of, get the size of, or declare a pointer to a managed type ('Form1.CameraInfo')" error.
public struct AuthParam
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string server_ip;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
public string username;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
public string password;
};
[StructLayout(LayoutKind.Sequential)]
public struct CameraInfo
{
public int index;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
public string devicename;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1000)]
public string smallrtsp;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1000)]
public string bigrtsp;
};
[StructLayout(LayoutKind.Sequential)]
public struct SingleDevice
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 50)]
public string deviceid;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
public string devicename;
public int flag_onuse;
public int cameralist_size;
public CameraInfo *cameralist;
};
[StructLayout(LayoutKind.Sequential)]
public unsafe struct DeviceList
{
public int listsize;
public SingleDevice *singledevicelist;
};
[DllImport("c:\\lib\\api_client.dll")] public static extern int capi_init();
[DllImport("c:\\lib\\api_client.dll")] public static extern int capi_disabled();
[DllImport("c:\\lib\\api_client.dll")] public static extern int capi_GetServerTimeCode(string ip, ref uint timecode);
[DllImport("c:\\lib\\api_client.dll")] public static extern int GetDevicelist (AuthParam auth_para,ref DeviceList devicelist);
is there any way to achieve this convertion?

i think this error because of the different nature of c++ (un-managed code) and c# (managed code), so maybe using System.IntPtr as a pointer to your camera struct.
please consider this question here, and you can find about P/Invoke Interop Assistant which is an open source tool to convert your code from the un-managed code to a managed C# code. with a small blog article about C++/C# interoperability

Available Resolutions For a specific Screen

I might have 2 monitor/screens connected to my machine.
I want to know all Avaliable resolutions for a specific screen (I have an instance of type System.Windows.Forms.Screen).
I've seen the following:
How to list available video modes using C#?
List of valid resolutions for a given Screen?
but they all give results for all monitors and not just a specific one. Any suggestions? Thanks!!!
Edit 1:
This is the info about my 2 screens:

In the first of those links you're told about EnumDisplaySettings. Take a few seconds to lookup that function and the FIRST PARAMETER is the
string that specifies the display device about whose graphics mode the
function will obtain information.
Here's a sample class to fetch information about displays. I've deliberately omitted DEVMODE since you've already got it.
public class NativeMethods
{
[DllImport("user32.dll")]
public static extern bool EnumDisplaySettings(string deviceName, int modeNum, ref DEVMODE devMode);
[DllImport("user32.dll")]
public static extern bool EnumDisplayDevices(string deviceName, int modeNum, ref DISPLAY_DEVICE displayDevice, int flags);
}
[StructLayout(LayoutKind.Sequential)]
public struct DISPLAY_DEVICE
{
public int cb;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string DeviceName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
public string DeviceString;
public int StateFlags;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
public string DeviceID;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
public string DeviceKey;
}
static class Display
{
public static List<DISPLAY_DEVICE> GetGraphicsAdapters()
{
int i = 0;
DISPLAY_DEVICE displayDevice = new DISPLAY_DEVICE();
List<DISPLAY_DEVICE> result = new List<DISPLAY_DEVICE>();
displayDevice.cb = Marshal.SizeOf(displayDevice);
while (NativeMethods.EnumDisplayDevices(null, i, ref displayDevice, 1))
{
result.Add(displayDevice);
i++;
}
return result;
}
public static List<DISPLAY_DEVICE> GetMonitors(string graphicsAdapter)
{
DISPLAY_DEVICE displayDevice = new DISPLAY_DEVICE();
List<DISPLAY_DEVICE> result = new List<DISPLAY_DEVICE>();
int i = 0;
displayDevice.cb = Marshal.SizeOf(displayDevice);
while (NativeMethods.EnumDisplayDevices(graphicsAdapter, i, ref displayDevice, 0))
{
result.Add(displayDevice);
i++;
}
return result;
}
public static List<DEVMODE> GetDeviceModes(string graphicsAdapter)
{
int i = 0;
DEVMODE devMode = new DEVMODE();
List<DEVMODE> result = new List<DEVMODE>();
while (NativeMethods.EnumDisplaySettings(graphicsAdapter, i, ref devMode))
{
result.Add(devMode);
i++;
}
return result;
}
}

How to pinvoke unicode version of SHGetFileInfo (c#)?

I tried this:
public struct SHFILEINFOW
{
public IntPtr hIcon;
public int iIcon;
public uint dwAttributes;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260 * 2)]
public string szDisplayName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80 * 2)]
public string szTypeName;
}
[DllImport("shell32.dll")]
public static extern IntPtr SHGetFileInfoW(IntPtr pIDL, uint dwFileAttributes, out SHFILEINFOW psfi, uint cbFileInfo, SHGFI uFlags);
String DisplayName = shInfoW.szDisplayName;
But DisplayName contain only the first char

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260 * 2)]
ByValTStr means "same as the class or structure". But you didn't specify the CharSet attribute for the structure. It defaults to CharSet.Ansi so the string is getting marshaled as though it was a 8-bit character string. Since the real string is Unicode, you'll indeed get very high odds for only getting the first character. Fix:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct SHFILEINFOW {
// etc...
}

SetupDiEnumDriverInfo always return with Error 259 (No more Data available)

I am trying to access information about drivers associated with devices in C# utilizing the win32 APIs.
I have managed to enable/disable devices (so the handles I am retrieving seem OK), however I have no luck when trying to call SetupDiEnumDriverInfo.
This is the code I am using:
private List<String> ListCompatibleDrivers(IntPtr hDevInfo, SP_DEVINFO_DATA devInfoData)
{
List<String> result = new List<String>();
try
{
SP_DRVINFO_DATA drvInfo = new SP_DRVINFO_DATA();
for (int i = 0; SetupDiEnumDriverInfo(hDevInfo, devInfoData, SPDIT_CLASSDRIVER, i, drvInfo); i++)
{
result.Add(drvInfo.Description);
}
if (result.Count < 1)
{
result.Add(Marshal.GetLastWin32Error().ToString());
}
return result;
}
catch
{
throw;
}
}
Where the parameters can be assumed to be okay (as I said, other methods from the setup API use them successfully).
These are the struct and the DllImport which might be corrupt:
[StructLayout(LayoutKind.Sequential)]
public class SP_DRVINFO_DATA
{
public Int32 cbSize;
public Int32 driverType;
public UIntPtr reserved;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=256)]
public String description;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=256)]
public String mfgName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=256)]
public String providerName;
public FILETIME driverDate;
public Int64 driverVersion;
};
[DllImport("setupapi.dll", SetLastError = true)]
public static extern bool SetupDiEnumDriverInfo(IntPtr lpInfoSet, SP_DEVINFO_DATA deviceInfoData, UInt32 driverType, Int32 memberIndex, SP_DRVINFO_DATA driverInfoData);
The API call returns with false immediately, the Marshal.GetLastWin32Error().ToString() returns 259, which is ERROR_NO_MORE_ITEMS.
I just don't get it, and my hopes are high I am just making some stupid mistake that I am not able to see because I have read hardly anything but msdn lately, and it gets incredibly tiring...
Any help is greatly appreciated, thanks a lot!

Well off the top I can tell you you don't match the function signature which should be:
[DllImport("setupapi.dll", SetLastError = true, charset=Charset.Unicode)]
[return:MarshalAs(UnmanagedType.Bool)]
private static extern bool SetupDiEnumDriverInfo(
[In] IntPtr lpInfoSet,
[In, Optional] SP_DEVINFO_DATA deviceInfoData,
[In] UInt32 driverType,
[In] Int32 memberIndex,
[Out] out SP_DRVINFO_DATA driverInfoData);
That out is important as it specifies that it needs to pull back out the data from the PInvoke.

There are several problems with the struct, the most annoying being that one has to specify pack=4 so the native code will find the correct entry points.
This works:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode, Pack = 4)]
public struct SP_DRVINFO_DATA
{
public int cbSize;
public int DriverType;
public UInt32 Reserved;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string Description;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string MfgName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string ProviderName;
public System.Runtime.InteropServices.ComTypes.FILETIME DriverDate;
public long DriverVersion;
}
Of course it is a god idea to actually prefix the P/Invokes with Charset=Charset.Unicode, too.

Here are the API and struct definitions that both worked on x64 and x86. I am adding also SetupDiGetDriverInfoDetail, good chance that you'll also need it.
API:
DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern bool SetupDiGetDriverInfoDetail(
IntPtr DeviceInfoSet,
ref SP_DEVINFO_DATA DeviceInfoData,
ref SP_DRVINFO_DATA DriverInfoData,
ref SP_DRVINFO_DETAIL_DATA DriverInfoDetailData,
Int32 DriverInfoDetailDataSize,
ref Int32 RequiredSize);
[DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern bool SetupDiEnumDriverInfo(
IntPtr DeviceInfoSet,
ref SP_DEVINFO_DATA DeviceInfoData,
int DriverType,
int MemberIndex,
ref SP_DRVINFO_DATA DriverInfoData);
structs:
#if !WIN64
[StructLayout(LayoutKind.Sequential, Pack = 2, CharSet = CharSet.Unicode)]
#else
[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
#endif
public struct SP_DRVINFO_DATA
{
public int cbSize;
public uint DriverType;
public UIntPtr Reserved;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string Description;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string MfgName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string ProviderName;
public System.Runtime.InteropServices.ComTypes.FILETIME DriverDate;
public ulong DriverVersion;
}
#if !WIN64
[StructLayout(LayoutKind.Sequential, Pack = 2, CharSet = CharSet.Unicode)]
#else
[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Unicode)]
#endif
public struct SP_DRVINFO_DETAIL_DATA
{
public Int32 cbSize;
public System.Runtime.InteropServices.ComTypes.FILETIME InfDate;
public Int32 CompatIDsOffset;
public Int32 CompatIDsLength;
public IntPtr Reserved;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public String SectionName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public String InfFileName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public String DrvDescription;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1)]
public String HardwareID;
};

Passing a struct by reference from managed to unmanaged code?

my struct looks like this in c code:
typedef struct _REQUEST {
char D [_D_MAX+1];
char M [_M_MAX+1];
char T [_T_MAX+1];
char ClRef [_CL_REF_MAX+1];
char load [_LOAD_MAX];
ULONG loadLen;
} _REQUEST, *LP_REQUEST;
in c# like this:
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
public struct _REQUEST_STRUCT {
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string D;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string M;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string T;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 20)]
public string clRef;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1200)]
public string Load;
public UInt32 LoadLen;
}
the method I am calling is like this in c:
int
AJ_STDCALL
SimpTran (const char* svc_name,
const LP_REQUEST query,
LP_RESPONSE response)
{
//init stuff
//Validate input parameters
if ( query == NULL )
return(ERR_QUERY_NULL);
if (query->loadLen == 0)
return (ERR_QUERY_NULL);
}
in c#:
[DllImport(LINUXLIB, CallingConvention = CallingConvention.StdCall)]
public static extern int SimpTran(string serID, ref _REQUEST_STRUCT request, out IntPtr response);
and i am calling it like this:
p_request_struct = new _REQUEST_STRUCT();
// fill p_request_struct
// response
p_response_struct = new _RESPONSE_STRUCT();
// initialize unmanaged memory to hold return struct
IntPtr ptrRet = Marshal.AllocHGlobal(Marshal.SizeOf(p_response_struct));
Marshal.StructureToPtr(p_response_struct, ptrRet, false);
iRet = SimpTran(SerID, ref p_request_struct, out ptrRet);
I am getting null query! In C code query==null is true and it returns null. But I am populating the request struct?
Do I have to allocate memory for that as well?