Channel 9 - Discussions by cosminb

Tech Off - Computer Science Final Year Project

cosminb — Wed, 19 Apr 2006 15:00:15 GMT

I was in your situation a year ago (although a bit different). I am a student of Industrial Automatics and Informatics. I didn't want to go deep into microcontrollers, capacitors and the like, I am a software developer, and I wanted my project to be mainly focused on programming, rather than designing circuits. However this was not entirely possible, so I had to stick some hardware stuff also.

A professor gave me an excellent idea, which wasn't quite original, but still, it saved me. He told me to build a 3D object scanner. The hardware part consists of controlling a stepper motor through the parallel port, which is quite easy and there is alot of dcumentation about this on the internet. The other part consists of using a webcam, setting its parameters and taking shots.

The working principle can be found here (it's not my site): http://www.muellerr.ch/engineering/laserscanner/default.htm

For this I am using C# 2.0, Visual Studio 2005 Express Edition, Avalon/WPF, DirectShow, Direct3D, and maybe more. Anyway, the project isn't yet finished, after presenting it, I wil most likely put it somewhere, with source code included.

Tech Off - extending WPF/Avalon/XAML - webcam preview

cosminb — Fri, 31 Mar 2006 06:24:59 GMT

Well, I just got some comments on this one, and it doesn't have a nice way around: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=296765&SiteID=1

I will keep asking, until I get a clear view on how to do it.

Edit:

So far I've managed to get it to work in Windows Forms and Direct3D, if you're interested in some code.

Tech Off - extending WPF/Avalon/XAML - webcam preview

cosminb — Mon, 27 Mar 2006 11:11:03 GMT

Actually what I'm trying to do is to target WPF, not Windows Forms. Windows Forms are already covered by my library.

So this is what I want to implement in Avalon: I want to display the preview video (taken directly from the webcam) in a similar way to how MediaElement works. So I want to be able to preview inside various shapes, or in 3D (I've seen a sample in Hands-On-Labs where there was a video file playing this way: inside shapes, and on the faces of a cube).

Tech Off - extending WPF/Avalon/XAML - webcam preview

cosminb — Sun, 26 Mar 2006 10:25:09 GMT

Hello C9ers,

I'm having some trouble figuring out how to do this: I've developed a camera library in C++/CLI which I use further in C# apps. After making it accessible to Windows Forms and Direct3D, I want to give Avalon/WPF a try, but this is where I got a bit stuck (lack of proper information). As you can see from the thread's title, I want to achieve
the same functionality that currently is given by MediaElement/MediaPlayer. I want to be able to output my webcam preview video to any Visual element in WPF. How do I do that? Do I need to subclass MediaElement? Or MediaPlayer? Or something else. And how do I customize it? I hope someone has an answer to this really soon, I'm
betting my final year project on this.

Thanks in advance,

Cosmin.

P.S. Also, I want to know if C++/CLI can be used to subclass the controls, or it has to be done in C#.

I've tried several places to get this info, noone seems to care... I hope C9 will.

Tech Off - Writing a managed version of ICreateDevEnum

cosminb — Sat, 11 Mar 2006 20:51:57 GMT

Actually the whole problem reduces to being able to pass an interface as a parameter to a function:

namespace InterfaceTest
{

    public interface class Intf
    {
        void Read();
    };

    public ref class Class1
    {
        void Something(Intf i)
        {
        }
    };

}

This yields on the function 'Something':

error C3149: 'InterfaceTest::Intf' : cannot use this type here without a top-level '^'

Thanks

Tech Off - Writing a managed version of ICreateDevEnum

cosminb — Sat, 11 Mar 2006 20:10:24 GMT

I have the following interface from "strmif.h" (DirectShow stuff):

    MIDL_INTERFACE("29840822-5B84-11D0-BD3B-00A0C911CE86")
    ICreateDevEnum : public IUnknown
    {
    public:
        virtual HRESULT STDMETHODCALLTYPE CreateClassEnumerator(
            /* [in] */ REFCLSID clsidDeviceClass,
            /* [out] */ IEnumMoniker **ppEnumMoniker,
            /* [in] */ DWORD dwFlags) = 0;

    };

I have found it described in C# like this (in a project called DShow.NET):

    [ComVisible(true), ComImport,
    Guid("29840822-5B84-11D0-BD3B-00A0C911CE86"),
    InterfaceType( ComInterfaceType.InterfaceIsIUnknown )]
public interface ICreateDevEnum
{
        [PreserveSig]
    int CreateClassEnumerator(
        [In]                                            ref Guid            pType,
        [Out]                                        out UCOMIEnumMoniker    ppEnumMoniker,
        [In]                                            int                    dwFlags );
}

The generated MSIL for the function is:

.method public hidebysig newslot abstract virtual
        instance int32 CreateClassEnumerator([in] valuetype [mscorlib]System.Guid& pType,
                                              [out] class [mscorlib]System.Runtime.InteropServices.UCOMIEnumMoniker& ppEnumMoniker,
                                              [in] int32 dwFlags) cil managed preservesig
{
} // end of method ICreateDevEnum::CreateClassEnumerator

And now my question is: How to represent this interface in C++/CLI? I use VS2005, and tried several times, but it doesn't compile. I am stuck on the IEnumMoniker parameter, don't know how to declare it.

Does anyone have an idea on how to write this interface in C++/CLI, so that I am able to cast the COM server 'SystemDeviceEnum' to the interface 'ICreateDevEnum'?

Thanks,
Cosmin

Tech Off - Discussion around the Coding4Fun Some Assembly Required Articles

cosminb — Sat, 31 Dec 2005 18:33:06 GMT

I am also having problems with the WIA WebCam source code. It does compile, but whenever I want to configure it (select the device), immediately after clicking on configure I get an exception:

Exception from HRESULT: 0x80210015
Source: Interop.WIA
at WIA.CommonDialogClass.ShowSelectDevice(...)

Anyone encountered this error? I use a Chicony TwinkleCam Pro DC2120 webcam. Also, it is listed in the "Scanners and Cameras" section of the Control Panel.

Does anyone know what the problem is?