Jun 17, 2009 A workaround for a missing file, “dxtrans.h” in DirectX SDK

The ISampleGrabber interface of DirectShow enables an application to retrieve individual frames from various types of movie files. This interface is defined in “qedit.h” which used to be installed with DirectX SDK until DirecX SDK version 8. DirectShow (including “qedit.h”) is not a part of DirectX SDK any more and now is included in Microsoft Windows SDK (which has been called Platform SDK for a while). Windows SDK is installed as a part of Visual Studio 2008, so you don’t need to install it additionally to use DirectShow (unless you want the latest version of Windows SDK). You need to install DirectX SDK though because “qedit.h” is still dependent on “dxtrans.h” which is shipped with DirectX SDK.

You will see an error message, however, if you try to compile “qedit.h” with the latest version of DirectX SDK. (the current version is DirectX SDK – March 2009)

C:\Program Files\Microsoft SDKs\Windows\v6.0A\include\qedit.h(498) : fatal error C1083: Cannot open include file: ‘dxtrans.h’: No such file or directory

The reason is because “dxtrans.h” is not included in the latest version of DirectX SDK any more (from DirectX SDK – November 2007) although “qedit.h” is still dependent on it. (I know it’s absurd, but that’s what Microsoft does) I found an article posted by people who already were troubled with this problem. The point is that the part of “qedit.h” which depends on “dxtrans.h” is not necessary to use DirectShow, so you comment it out in “qedit.h” and the error will go away. (For the details, click HERE) The other solution which I like better is to define some keywords before including “qedit.h” to prevent the “dxtrans.h” dependent code from being compiled. In that way you don’t have to edit “qedit.h” itself.

#pragma include_alias( “dxtrans.h”, “qedit.h” )
#define __IDxtCompositor_INTERFACE_DEFINED__
#define __IDxtAlphaSetter_INTERFACE_DEFINED__
#define __IDxtJpeg_INTERFACE_DEFINED__
#define __IDxtKey_INTERFACE_DEFINED__
#include <qedit.h>

May 31, 2009 How to convert BSTR to LPCTSTR

In a project, I’ve had to deal with a pointer of a BSTR string returned to an event handler of an ActiveX control. I wanted to convert it to LPCTSTR, and a simple implicit type-casting worked seamlessly when I tried it in a test project.

void put_UseServer(LPCTSTR newValue);

void ServerChanged(BSTR* NewServer)
{
put_UseServer(*NewServer); // This conversion works only in Unicode Character Set
}

However, when I copied the same code into my actual project, it caused an error. The reason was that my project used the Multi-byte Character Set whereas I tested the code in the Unicode Character Set. The simplest solution I found which also works in the Multi-byte Character set is like the following.

void put_UseServer(LPCTSTR newValue);

void ServerChanged(BSTR* NewServer)
{
put_UseServer(COLE2CT(*NewServer)); // Use ATL String Conversion Class
}

More information about ATL and MFC String Conversion is on the MSDN website.

May 30, 2009 Some VS2005 and VS2008 wizards pop up script error after installing IE8

I experienced this trouble when I tried to add a variable with a wizard in Visual Studio 2008. I never suspected IE8, but MS disappointed me again. Anyway, here is a workaround posted in Visual C++ Team Blog and it seems to work. For the details, click HERE

Please follow the following steps:

- Open regedit (on a 64-bit OS, open the 32-bit regedit)

- Under “HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones“, create a new key called 1000 (if it isn’t already there)

- Under 1000, create a DWORD entry with:
o Name = 1207
o Type = REG_DWORD
o Data = 0×000000

For the workaround to work on VS2005, however, the VS2005 SP1 (and VS2005 SP1 Update for Windows Vista) has to be installed.