如何将非托管C ++ DLL添加到Silverlight 5项目中

Question

I need to use a my own unmanaged C++ dll into Silverlight 5 project.

As I am able to use it using dllImport ie

   [DllImport(@"D:\myLib\Debug\myLib.dll")]
    static extern int add(IntPtr ptr);

It works fine as I metioned a absoulte path in DllImport. But my problem is, I want to use the relative path.

As I need to add unmanaged C++ dll in my silverlight 5 project and specify path from there. I am investigating from last two days I did not find any solution for this issue.

Only I found one related link mentioned below but it also does not help.

http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.dllimportattribute.dllimportattribute.aspx

As It suggest how to embed your unmanaged dll into managed assembly. I tried this approach but I am getting "BadImageException".

Please suggest to over come to this issue as it is really urgent for me.

Thanks,

Vipin

Answer 1

When Silverlight 5 Release Candidate was made public, I created some support methods for handling this issue of bundling unmanaged non-system DLL:s with your Silverlight 5 RC application. The solution is still valid, since Microsoft did not add any support to deal with the bundling issue in Silverlight 5 RTM.

What I do is basically to bundle the unmanaged DLL as a resource file. Through a helper method manually invoked eg in the application startup event handler the resource is copied to a predefined location on disk. This location is then also included in the system PATH during execution.

Elevated trust is required (of course).

More details on this solution can be found in this blog post.

All code associated with this solution, including sample tests, can be found on Github .

UPDATE

As pointed out in the comment below by Simon Mourier, one option would also be to load into memory (and release upon application exit) the unmanaged DLL by calling the Kernel32 LoadLibrary function after the DLL has been unpacked from the resources. This approach for Silverlight is described in more detail in this blog post.