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Shell Extensions for .NET Assemblies

By , 17 Nov 2005
 

About the Shell Extensions for .NET Assemblies

These shell extensions were written to help distinguish between .NET assemblies and Win32 libraries, as well as give extra information about the assemblies without having to drop to a command-prompt to use the SDK and CLR tools. These shell extensions function similar to the loader that makes both .NET and VB (pre-.NET) possible as executable code: the PE/COFF header. As such, the library is very fast and won't hinder your file system browsing experience. A recent update further enhances performance by skipping assembly detection on slow paths, such as UNC paths or drive mappings to remote filesystems via VPN.

Provided in this library are:

  1. Overlay icons for .NET assemblies (.dll)

    Overlay icon 

  2. Column handlers to show the public key token and specific type of .NET assemblies.

    Column handlers 

  3. Automation object for getting the above information in your own applications and libraries.

The Automation Object

Not only does this tool help you distinguish between .NET assemblies and Win32 applications and libraries, but it also provides you with a simple automation object that these shell extensions use.

To generate code from the type library, add a reference or #import the type library named "AsmShell 1.0 Type Library". Use the members of the IAssemblyInfo automation interface as follows:

  • IAssemblyInfo::IsAssembly([in]BSTR path, [out, retval]VARIANT_BOOL* retVal)
    Returns true if the specified file is an assembly, false if it is not, and raises errors when problems occur.
  • IAssemblyInfo::GetFileType([in]BSTR path, [out, retval]FileType* retVal)
    Returns a FileType enumeration member depending on the information for the specified file in the PE/COFF header.
  • IAssemblyInfo::GetPublicKeyToken([in]BSTR path, [out, retval]BSTR* retVal)
    Returns the public key token for the specified assembly.
  • IAssemblyInfo::GetPublicKey([in]BSTR path, [out, retval]SAFEARRAY(BYTE)* retVal)
    Returns the public key as a byte array for the specified assembly. This is not supported by JScript or VBScript, both of which only support an array of VARIANTs.

For each method, late-binding languages like Visual Basic will use the return value (marked with [out, retval]) as the return type of the method, also getting rid of the need for the parameter labeled with the specified attributes above.

So, in VB6 and .NET (C#, VB.NET, et. al.), the methods signatures would look like:

bool IsAssembly(string path);
FileType GetFileType(string path);
string GetPublicKeyToken(string path);
byte[] GetPublicKey(string path);

Requirements

You may be required to reboot if files being installed are currently loaded. If you have Windows XP and the previous condition is false, no reboot should be necessary. If you're using Windows 98, ME, or 2000, you should either log off and back on or reboot your system if the overlay icon is not present; the column handlers should be ready immediately after the installation is finished.

Changes

  • November 17, 2005
    • Note: late article update for an earlier release
    • Added support to display x86 (and MSIL) for assemblies, as well as IA64 and x64
  • May 30, 2005
  • August 29, 2004
    • Added localizability
    • String caching for better performance
    • Support for .NET modules (.netmodule)
  • October 15, 2003
    • Added condition that files should not be parsed for slow paths (ex: VPN)
  • September 19, 2002
    • Initial release to the web on The Code Project

Disclaimer

THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR HIS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

License

This article, along with any associated source code and files, is licensed under The Microsoft Public License (Ms-PL)

About the Author

Heath Stewart
Program Manager Microsoft
United States United States
Member
Heath Stewart is a happily married software engineer originally from the Midwest and a graduate of Iowa State University. Heath start programming early in life and enjoys continuous research and development in new languages, frameworks, and platforms. Fluent in many different programming languages, he has developed many large-scale software solutions for companies in different areas, such as Internet filtering, intrusion detection systems, production management systems, and web applications for various purposes. He also enjoys photography.
 
Currently, Heath is a Program Manager in the Visual Studio Professional Deployment Experience (VSPro DEX) team at Microsoft. Previous to his employment, he was a Microsoft MVP for Visual C#.
 
He is also a CodeProject protector and is happy to help the development community.

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GeneralIcon LocationmemberSameers (theAngrycodeR )25 Sep '05 - 10:40 
Nice job. Weldone.
 
I am afraid if there is a way to set the location of the icon? Like by default it is at right bottom, what if I want to put that on top left or top right or bottom left corner?
 
Any idea?
 
Best wishes,
Sameers
GeneralRe: Icon LocationprotectorHeath Stewart25 Sep '05 - 14:54 
My extension is not configurable like that. You can change the overlay icon to change the position of the overlay, however. It's just a regular icon with both transparent and non-transparent bitmaps.
 
This posting is provided "AS IS" with no warranties, and confers no rights.
 
Software Design Engineer
Developer Division Customer Product-lifecycle Experience
Microsoft
 
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GeneralRe: Icon LocationmemberSameers (theAngrycodeR )26 Sep '05 - 0:21 
YEs, your extension is not. But I was trying on such extension in C# but I couldnt find anyway int the interface methods/parameters etc to set the location of overlay icon nor the MSDN documentation discuss on this. I know one method could be to have a transparent icon as per location need so we have four different icons which are transparent but icon image is on either corner. But any good solution would be better.
 
Also, is there anyway to load icon from the application resources and then return that as overlay icon? Currently the interface structure forces to return icon location file name and it's index. Any idea would be appreciated.
 
Thanks,
Sameers
AnswerRe: Icon LocationprotectorHeath Stewart26 Sep '05 - 4:24 
Again, you can change your icon that you plan on using for the overlay. Look at my icon in the project. It's toward the bottom left. For your icon, move it somewhere else. Your icon dimensions must still be the same as the size of the icon you plan on overlaying, i.e. a 16x16 icon to overlay over 16x16 icons, 32x32 over 32x32 icons, etc. You might also consider different pixel depths that must match up too, including alpha channels for 32-bit icons.
 
I highly recommend not using managed code for shell extensions. The CLR doesn't require a large working set and when that's loaded into the Explorer process you've increased the working set by many megabytes. Since Explorer is a ubiqitous process that working set will be constant unless the CLR crashes and is unloaded by the default host (mscoree.dll) or a custom host if you're using one. Writing your extensions natively is simple in this case (most shell extensions are) and don't require you to create and deploy interop assemblies because the interfaces are already defined in headers for native compilation (or even for Managed C++, but then you're still utilizing the CLR).
 
If you insist on using managed code, then you'll need to do one of the following for an overlay extnesions:
  1. Store the .ico separate from your assembly and return the path to it.
  2. Store the icon in a separate native resource DLL.
  3. Build your managed assembly, disassemble it using ildasm.exe, add your icon to the RC file, then re-assemble it using ilasm.exe with the appropriate parameters.
If you don't change the assembly attributes that constitute the default RC file you could just make that part of the build process, using the same RC file over and over again. That will embed the icon in the .rsrc section of the PE/COFF executable. You will not be able to use the icon straight from your resources because they are stored in a completely separate fashion.
 
This posting is provided "AS IS" with no warranties, and confers no rights.
 
Software Design Engineer
Developer Division Customer Product-lifecycle Experience
Microsoft
 
[My Articles] [My Blog]
GeneralRe: Icon LocationmemberSameers (theAngrycodeR )26 Sep '05 - 10:23 
Thank you very much for your information. I have written this code in C# .NET (2005) and your descriptions says that there is no way to point icon on specific location (like original icon is of 32*32 and my overlay icon is of 8*8 which I wanted to point on bottom left corner). It also looked to me the same as well as I couldnt find any hint in MSDN and other locations on the net. However, your idea looks interesting regarding getting icon from resource. Thanks again,
 
Sameers
AnswerRe: Icon LocationprotectorHeath Stewart26 Sep '05 - 11:15 
You need to make the overlay icon 32x32 and then you can position your non-transparent pixels anywhere. Open my overlay icon in VS and view the 32x32 pixel icon and you'll see the ".net" portion is in the corner. Move that to another portion of the 32x32 icon.
 
This posting is provided "AS IS" with no warranties, and confers no rights.
 
Software Design Engineer
Developer Division Customer Product-lifecycle Experience
Microsoft
 
[My Articles] [My Blog]
GeneralRe: Icon LocationmemberSameers (theAngrycodeR )26 Sep '05 - 11:19 
Yes, that is the same I got from your last reply. We need to design our icon in such way so that it displayed on the desired location (as your current icon of ".net" is displayed on bottom right, but the icon should be changed to display it on top left, no change in the code itself).
 
Sameers
AnswerRe: Icon LocationprotectorHeath Stewart26 Sep '05 - 11:25 
And I'm not telling you to change your code, just change the position of the non-transparent pixels. Your overlay icons should match in size to the icon you're overlaying, so that if the current icon for a file type is 32x32, you'd have a 32x32 icon resource. If it's both 32x32 and 24x24, then you'd use a .ico file with both sizes. Windows will pick the correct size or default to the next smaller size if the right size is not provided. If all you're using is an 8x8 icon then you won't have control over where it's position. Make a .ico file with different sizes of icons; remember that a single .ico can contain different resolutions and pixel depths. Open my .ico up in VS or another icon editor. If in VS, use the Image -> Current Icon Image Types menu to change the size and depth of the displayed icon.
 
By defining different icon types that match the size of the icon on which you want to overlay your icon you can control how your overlay displays because you can control where within its bounding region the non-transparent pixels are.
 
This posting is provided "AS IS" with no warranties, and confers no rights.
 
Software Design Engineer
Developer Division Customer Product-lifecycle Experience
Microsoft
 
[My Articles] [My Blog]

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