Hi, It seems MSDN does not have sufficient documentation on IExtractImage ( shell extension for generating custom thumbnail). So far, I already. The IExtractImage interface is used to request a thumbnail image from a Shell C# Definition: You can use this enum for the IExtractImage. I believe nearly all IExtractImage samples (you find searching) are based on this article’s code, due to naming convention, comments, and so on, that are carried.

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Thank you for helping keep Tek-Tips Forums free from inappropriate posts. The Tek-Tips staff will check this out iextractimagr take appropriate action. Click Here to join Tek-Tips and talk with other members! Join your peers on the Internet’s largest technical computer professional community. It’s easy to join and it’s free.

Register now while it’s still free! Close this window and log in. By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. So far, I already have the public class that will be registered as the thumbnail extension for a particular file extension eg.

So far, when I open Explorer and view thumbnails of. But when I do a refresh, the thumbnails are gone, just white background. Also, when I right click or double click an. This is the snippet of the extension class: DrawLine p, 0, 0, imgSize. You are doing all that just to get a thumbnail?

GetThumbnail ; That will work too Thanks for the response.

What I have is a shell extension for Windows Explorer. The snippet I provided is just to test if the shell extension, when properly registered, really works with Windows Explorer. Generating the thumbnail is the easy part. My problem is making the shell extension work properly. At least it does the first time the folder is viewed. But when I refresh, the thumbnails are no longer generated. Much worse, when I try to double-click the file to open, or just right-click, Explorer crashes.

Forgot to close this thread. I remembered how GC would move IntPtr rendering them useless. So I have to work with unsafe pointers so I can properly return the bitmap object. Also I didn’t noticed the Extract parameter is a pointer to a handle, and am passing the handle improperly. In fact, iexteactimage to dereference the pointer var and set the bitmap handle, which was quite tricky, but has a work around on C.


The Extract has IntPtr iextfactimage. To dereference, I needed to get the unsafe pointer via IntPtr. On a bit OS, this is an issue since the managed Int32 is really just bits. The only feasible solution I can think is to get the OS version, then conditionally apply a proper integral cast if 32 or bit.

С# получить эскиз из файла через windows api

The thumbnails are working now and explorer no longer crashes. Could you please post your corrected Extract method? Hi jcorreia, Basically I have Hello phinoppix Thanks for the reply. I had actually got this to work during the weekend, but in a different way: Some comments about your implementation, I’m not sure if you iextractimwge had a typo, but there are some errors on your interfaces. You’re missing the parameter for Extract and return value for GetLocation.

Hello again At first i thought that too and it might just be one of those mistakes that work.

I looked through some VB samples for this and they had IExtractImage implemented like that – no parameter on Extract and no return code in GetLocation – and it worked. Connected to this is the return iextractimae an int in Extract. Instead of using the out parameter like the specs say i used what was in those samples see vb shell extensions I took the easy way and just mapped things from VB to C straight out.

I was using the GetHBitmap as a means to get to the. ToInt32 which gave me the IntPtr of the bitmap i needed. I will try to use your suggestion, as it does look better. Again, thanks for the suggestions and i iextrachimage post here if i finally get it working. Red Flag This Post Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, iextracctimage, illegal, vulgar, or students posting their homework.

Students Click Here Join Us! Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden. How do I iextractjmage my COM assembly is free-threaded? I can see that the assembly’s threading model is registered as “Both”, is this different from being a free-threaded?


Thumbnail Handlers

Why do the thumbnails disappear every time I hit refresh? I hope someone can help me on this. Help on using IExtractImage You are iectractimage all that just to get a thumbnail?

Help on using IExtractImage Thanks for the response. Help on using IExtractImage Forgot to close this thread.

The if block is necessary to test for processor type if 32 or 64 bit. Hope this helps RE: IRunnableTask is all but ignored. My interfaces are defined like so: I worked around this by creating a background thread in GetLocation and setting it to do the extraction work and then Thread. Join it in Extractbut its not very effective – in fact i’m not even sure its working as i intend it. So, to sum it up – the first code i posted Works-For-Me tmbut is not using Async.

With the changes to use Async, it crashes explorer as soon as GetLocation It seems to me it’s an inproperly implemented interface IExtractImage has the wrong signature its not a long and it should be something else but i have made some attempts and couldnt get it to work.

: IExtractImage (Interfaces)

This code works in Vista iexxtractimage XP, and i believe Vista automagically uses multithreads ignoring Async flags and return values anyway. Thanks, Joao Correia RE: Still, since you mentioned Works-For-Me tmI guess. NET interop does some magic on this. It also has a parameter, which is a buffer for the bmp handle, or more specifically, a pointer to the bmp handle.

As far as i understand, this means GetHbitmap is as good as creating another bitmap object, ending iextractinage with 2 bmps: After all, the Graphics class has an overload that takes in a GDI bmp handle. I’ll see if I can implement the asynchronous version this weekend, hopefully I can coz like you said, the documentation is really scarce.

If you finish it first, I hope you won’t mind posting your solution. Help on using IExtractImage Hello again At first i thought that too and it might just be one of those iextracgimage that work.