Enumerating WPD devices in C#

re: Enumerating WPD devices in C#

Matthias Muenzner — Fri, 14 Dec 2012 22:02:33 GMT

I just wanted to use that disassemble -> change -> assemble trick and it worked fine but

if you want to marshal long strings it will not work.

The compiler throws a DirectiveException (Marshaler restriction: Excessively long string)

So i changed the lines:

instance void GetDevices([in][out] string[] marshal([]) pPnPDeviceIDs,

[in][out] uint32& pcPnPDeviceIDs) runtime managed internalcall

instance void GetDevices([in][out] string[] marshal( lpwstr[]) pPnPDeviceIDs,

[in][out] uint32& pcPnPDeviceIDs) runtime managed internalcall

the changed c# code is:

void GetDevices([In][Out][MarshalAsAttribute(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPWStr)] string[] pPnPDeviceIDs, [In, Out] ref uint pcPnPDeviceIDs);

Greetings from a fellow explorer ^^

re: Enumerating WPD devices in C#

viewon01 — Sun, 04 Jan 2009 15:27:44 GMT

Hi,

I try to use the "GetStream" method but I got an exception "E_ACCESSDENIED".

It is on a "Zune" !

Here is the code :

uint optimalTransferSize = 0;

PortableDeviceApiLib.IStream wpdStream;

deviceResources.GetStream((string)music.Tag,

ref PropertyKeys.WPD_RESOURCE_DEFAULT,0, ref optimalTransferSize, out wpdStream);

Can you help me, I have no idea to solve this problem ?

Thanks

re: Enumerating WPD devices in C#

Tree — Thu, 21 Aug 2008 12:42:30 GMT

Thanks Chris, I'm glad there is a cleaner solution! I'll pass that on to the guys who maintain my device code now.

Tree

re: Enumerating WPD devices in C#

Ociter — Wed, 20 Aug 2008 22:27:21 GMT

Tree,

I figured out how to get at the returned pReadBytes for the sourceStream.Read function in case you are interested.

Chris

GCHandle hBytesRead = GCHandle.Alloc(new ulong(), GCHandleType.Pinned);

{

sourceStream.Read(streamBuffer, (int)optimalBufferSize, hBytesRead.AddrOfPinnedObject());

totalBytesRead += (ulong)hBytesRead.Target;

} while ((ulong)hBytesRead.Target > 0);

hBytesRead.Free();

re: Enumerating WPD devices in C#

Tree — Wed, 03 Oct 2007 17:24:25 GMT

jtackabury: Just digging out the contants and helper classes I use. I'll mail them to you shortly.

re: Enumerating WPD devices in C#

jtackabury — Wed, 03 Oct 2007 16:44:30 GMT

Tree: Would you be able to send me your WPDPropertyKey class? I seem to be having a hard time find the required header files and creating this class. If you can, please send it to jtackabury (AT) binaryfortress.com.

Thanks!

re: Enumerating WPD devices in C#

Tree — Fri, 07 Sep 2007 10:27:21 GMT

The way I rebuild the interop for .net 2 is simply to use the .NET 2.0 ildasm disassembler and ilasm assembler, You'll find them in different places. This is literally what I do:

1. Generate the initial interop in VS 2005 (or on the command line I guess)

2. Run "C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\Bin\ildasm" input\Interop.PortableDeviceApiLib.dll /out:pdapi2_0.il

3. Make interop tweaks

4. Reassemly the interop with: "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\ilasm" pdapi2_0.il /dll /output=output\Interop.PortableDeviceApiLib.dll

re: Enumerating WPD devices in C#

Ociter — Thu, 06 Sep 2007 21:18:19 GMT

Tree,

I'm pretty new at .NET and C# and would really appriciate your help.

Regarding your comment:

# re: Enumerating WPD devices in C#

Thursday, February 15, 2007 5:53 AM by Tree

I tested the interop mod mentioned in the blog update, and while it works fine with .NET 2.0, a runtime MissingMethodException is thrown when attempting to run code which calls GetDevices using .NET 1.1. I guess this is just a limitation in 1.1 when defining method signatures.

I am getting the MissingMethodException when calling GetDevices. I modified the il as specified by dimeby8 and thus it compiles. I have .NET 2.0 as well as .NET 1.1 installed on my machine. How do I specify .NET2.0?

Thanks a bunch,

Chris

re: Enumerating WPD devices in C#

Tree — Wed, 02 May 2007 16:36:32 GMT

Here's a bit of code which I use to read an xml doc. Some of it is specific to our code, but you should get the idea. I have to admit it's not perfect. The problem exists because the pReadBytes from the read call always returns 0, because the interop can't do anything else, so you can't tell if you've finished reading without a slow check for a \0 the buffer. I tried fixing the interop a number of ways, but I'm no expert and had no success.

My mods to the interop are fairly minimal, and not related to streams, although as I mentioned earlier I tweaks the remoteRead and remotewrite, but I don't use them anymore.

Here's the code I use which works:

XmlDocument GetXMLDocument(string fileId)

{

//need a contents object to get the propeties

IPortableDeviceContent content;

PortableDevice.Content(out content);

//get transfer interface to this device

IPortableDeviceResources resources;

content.Transfer(out resources);

IStream wpdStream;

uint optimalTransferSize = 0;

resources.GetStream(fileId, ref WPDPropertyKey.WPD_RESOURCE_DEFAULT, 0, ref optimalTransferSize, out wpdStream);

//convert to a useful stream object

System.Runtime.InteropServices.ComTypes.IStream sourceStream =

(System.Runtime.InteropServices.ComTypes.IStream)wpdStream;

XmlDocument document = new XmlDocument();

////////Stream bit

using (MemoryStream mStream = new MemoryStream(1000))

{

int totalBytesRead = 0;

byte[] streamBuffer = new byte[optimalTransferSize];

IntPtr pBytesRead = new IntPtr();

int writeBytes = 0;

{

sourceStream.Read(streamBuffer, (int)optimalTransferSize, pBytesRead);

if (pBytesRead.ToInt32() == 0)

writeBytes = Array.FindIndex(streamBuffer, CheckEndBuffer);

else

writeBytes = pBytesRead.ToInt32();

totalBytesRead += writeBytes;

mStream.Write(streamBuffer, 0, writeBytes);

} while ((writeBytes > 0) && (optimalTransferSize == writeBytes));

mStream.Flush();

mStream.Seek(0, SeekOrigin.Begin);

//load and interpret

if (sourceStream != null) document.Load(mStream);

}

return document;

}

re: Enumerating WPD devices in C#

jdawes — Wed, 02 May 2007 14:33:31 GMT

Hello Tree !

I have tried with ...ComTypes.IStream, but I get the same result.

Have you done any changes to the IPortableDeviceResources.GetStream in the interop ?

Could you please give me an example of how you do this ?