I'm working on a driver for a scanner. Got dll and header files from provider, aside of a manual in PDF, written in native C++ (dont have source code). Need to use it within a C# project but I'm having problems with the structs (either trying to read or send them).
I got the dll methods using the Command Prompt, demangling them in a website (since it has +100). Of course, I wont use all of them, just the ones I need. Didn't have problems with the ones using primitive data types, in fact, made the scanner turn on/off, scan and such.
My main problem is the following: I need to set some parameters, because with the default ones I'm not getting the needed info (and that's the MOST important thing I need, actually). The only way to do it is with a method that include 2 params: the ID (just an int) and the setting (an struct). That struct has internally not one, but 2 different structs instances (and one of them is an array, within another kind of struct as one of the params). In other words, gonna need to work with 4 different structs.
I declared all my structs, following the template provided in the .h file, and inmported the method. When I try to do a test it keeps giving me an error. I believe the problem is the array of structs. I tried with a normal passing, Marshaling, using a pin to array, changing data type, adding a "MarshalAs" with all bool vars... nothing seems to work.
Been trying to solve this for days already. Dont know what am I doing wrong (because this is my first time importing methods). I read about the C++/Cli thing but never worked with that either.
See code below (I kinda modified a little because of confidentiality of the information)
This is how is defined in the .h file (C++)
// The structs (won't add all parameters, but are basically the same type)
typedef struct _ImParam
{
UINT Format;
UINT Resolution;
UINT ColorDepth;
} IM_PARAM;
typedef struct _sValues
{
UINT Xpos;
UINT Ypos;
UINT Width;
UINT Height;
BOOL Milli;
} S_VALUES;
typedef struct _sProperties
{
BOOL Enable;
S_VALUES Properties;
} S_PROPERTIES;
typedef struct _DevParam
{
BOOL Enable;
UINT Font;
char Symbol;
IM_PARAM Image1;
IM_PARAM Image2;
S_PROPERTIES Properties[10];
UINT FeedMode;
} DevParam;
// more code, comments, etc. etc.
// This is how is defined
BOOL SetParameters( DWORD ID, DevParams DParam )
This is how I build the structs in C#
[StructLayout(LayoutKind.Sequential)]
public struct ImParam
{
public uint Format;
public uint Resolution;
public uint ColorDepth;
public ImParam(uint n)
{
Format = n;
Resolution = 300;
ColorDepth = 256;
}
};
[StructLayout(LayoutKind.Sequential)]
public struct sValues
{
public uint Xpos;
public uint Ypos;
public uint Width;
public uint Height;
public bool Milli;
public sValues(uint n)
{
Xpos = n;
Ypos = n;
Width = n;
Height = n;
Milli = false;
}
};
[StructLayout(LayoutKind.Sequential)]
public struct sProperties
{
public bool Enable;
public sValues Properties;
public sProperties(int n)
{
Enable = false;
Front = false;
Properties = new sValues(n);
}
};
// Commented code is from another attemp
[StructLayout(LayoutKind.Sequential)]
public struct DevParam
{
public bool Enable;
public uint Font;
public char Symbol;
public ImParam Image1;
public ImParam Image2;
public IntPtr Properties;
//public sProperties[] Properties;
public uint FeedMode;
public DeviceParameters(IntPtr SnP) //(int n)
{
Enable = true;
Font = 0;
Symbol = '?';
Image1 = new ImParam(3);
Image2 = new ImParam(3);
Properties = SnP;
/*Properties = new sProperties[n];
*for(int i = 0; i < n; i++)
* Properties[i] = new sProperties(0);*/
FeedMode = 1;
}
};
// .dll file path definition, some methods imported, etc. etc.
[DllImport(path, EntryPoint = "?SetParameters@@YGHKU_DevParam@@@Z")]
public static extern bool SetParameters(int ID, DevParam dParam);
And this is when I do call it (added commented code to show you my attemps)
static void Main(string[] args)
{
bool res = false;
int ID;
sProperties[] SnP = new sProperties[10];
for (int i = 0; i < 10; i++)
SnP[i] = new sProperties(0);
try
{
// Some code to turn on scanner, get ID value and such
/* Attemp1: Passing the struct normaly.
* Result: ArgumentException [HRESULT: 0x80070057 (E_INVALIDARG))]
* try
* {
* DevParam dParam = new DevParam(10);
* res = Class1.SetParameters(ID, dParam);
* Console.WriteLine(res);
* }
* catch (Exception e) { Console.WriteLine(e); }*/
/* Attemp2: Marshaling each element of the array.
* Result: The managed PInvoke signature doesnt mach the destination one
* int S = Marshal.SizeOf(typeof(sProperties));
* DevParam dParam = new DevParam(Marshal.AllocHGlobal(SnP.Length*S));
* IntPtr ptr = dParam.Properties;
* for (int i = 0; i < SnP.Length; i++)
* {
* Marshal.StructureToPtr(SnP[i], ptr, false);
* ptr += S;
* }
* try
* {
* res = Class1.SetDevParam(ID, dParam);
* Console.WriteLine(res);
* }
* finally { Marshal.FreeHGlobal(dParam.sProperties); }*/
/* Attemp3: Adding a Pin Pointer to struct
* Result: Exception (Object has no primitive data and it can't
* be transfered into bits blocks) */
GCHandle SpHandle = GCHandle.Alloc(SnP, GCHandleType.Pinned);
try
{
DevParam dParam = new DevParam(SpHandle.AddrOfPinnedObject());
res = Class1.SetParameters(ID, dParam);
Console.WriteLine(res);
}
catch (Exception e) { Console.WriteLine(e); }
finally { SpHandle.Free(); }
// More code for testing other methods and blahblahblah
}
catch (Exception e) { Console.WriteLine(e); }
Console.WriteLine("Finished");
Console.ReadKey();
}
What do I expect? Getting just a boolean result to see if method executed sucessfully (and of course, if true, scanner should have defined the new parameters)
What do I get? A bunch of exceptions.
Please, any help would be great. Thanks in advance.
PD: Sorry for that long post. PD2: I'm quite rockie, so please try to explain it "for dummies"
