How to dereference a pointer as a structure

I've an IntPtr which points to the location where a Bitmap stores its raw image, i.e. not pointer to the bitmap object, but pointer to the image data itself (which I obtained through BitmapData.Scan0)

Now I've a structure like this

VBCode Code:

Structure RGB
    B As Byte
    G As Byte
    R As Byte
End Structure

I need to be able to access the individual pixels (which I locate using the pointer) on the image as this RGB Structure.
In other words, it's like casting the pointer as a structure type. In C# it may be something like (RGB*) bmpptr;

Anyone know how?

Thanks in advance.

Doesn't the MSDN help topic for the Scan0 property essentially show you how to do that? The code example it provides gets all the RGB data into a Byte array. You would then create multiple instances of your structure from the elements of that array.

Thanks for your reply.
I know that method; that's precisely the method I want to avoid. I want to change it directly, right away, on the spot, with the help of a structure. This is why I want to dereference the pointer as a structure which I've defined. Copying to an array incurs a lot of overhead. My code runs in a tight loop so I hope to be able to change the data as fast as possible.

I only hope VB.net has a native method to do this, and I would like to know what it is. I dont want to use Marshal class's WriteByte or the WriteInts, nor do I want to use FillMemory API because they incur tiny bits of overheads.

Unless, the JIT inlines the function call, which I'm not sure.

Sounds to me like VB is the wrong language for this. I'd suggest writing a library in C# using unsafe code and then referencing that from your VB app, if that's an option.

thanks jmcilhinney for the advice.:wave:
unfortunately I'm not using C#.
The fact that they all are .NET compliant leads me to think VB.NET might have something like that, too.
I guess I'll just drop the idea and look for alternatives.
Speed is still an issue with VB.net, it seems.:(

VB.NET was never intended to support pointers. If wanted to do even medium-duty work with pointers in VB the code would get ugly very quickly. The language is simply not designed for it.