[VB6] Load Image from DLL

[James Rose]

I have to support an old (OLD!) VB6 app and now management wants to implement encryption for the files. I created a COM DLL in .NET that can encrypt and decrypt the files, and all that works fine. I would like to avoid creating files on the users hard disk, but for most files I simply must do so. However I thought I recalled that I could load an image directly from a DLL in VB6.... and yet I have not been able to find the solution.

My .NET DLL has a function "DecryptImage(sFile as string) as Image" that works fine within another .NET app. But within VB6 I can only find the "LoadPicture()" function and after 90+ minutes I can't find another solution.

Any thoughts?

[fhpuqrgrpgvirzhpujbj]

Your limited by VB's lack of pointers so the only thing I can think of is to use LoadImage from User32.dll.

[James Rose]

Thanks Omni, however that doesn't work the way I need it too. That API will pull a resource from within the file whereas my function needs to pull an image back from a function within the DLL. Close but not quite.

Again, thank you.

[fhpuqrgrpgvirzhpujbj]

  On 11/10/2010 at 19:42, jameswjrose said:

Thanks Omni, however that doesn't work the way I need it too. That API will pull a resource from within the file whereas my function needs to pull an image back from a function within the DLL. Close but not quite.

Again, thank you.

Oh I didn't realize you meant an image as a return result. You'll need to return an HBITMAP (eg. handle to a gdi bitmap) then blit it to the picturebox's surface.

[James Rose]

  On 11/10/2010 at 21:11, omnicoder said:

Oh I didn't realize you meant an image as a return result. You'll need to return an HBITMAP (eg. handle to a gdi bitmap) then blit it to the picturebox's surface.

Truly not to be snippy, but that's why I included the function I am using in .NET to avoid wasting your time. (no worries)

I have to return an actual image as it's not always used within a PictureBox. It looks like I'm going to have to use the file system to retrieve data. (drats)

Thanks though.

[fhpuqrgrpgvirzhpujbj]

Well there's no way to take the Image object from .net straight into VB6 anyway so I was assuming you'd have no problem with changing the return type. You could also use named pipes or memory mapped files, which never need to be saved on the disk.