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CImage Limitations with Earlier Operating Systems

Many CImage functions work only with newer versions of Windows: Windows 95/98 or Windows NT 4.0, or Windows 2000. This article describes the version limitations of certain methods.

CImage::PlgBlt and CImage::MaskBlt work with only Windows NT 4.0 or later. They will not work on applications running on Windows 95/98 or later.

CImage::AlphaBlend and CImage::TransparentBlt work with only Windows 2000 or later and Windows 98 or later because you must link with msimg32.lib to use these methods. (This library is available only to applications running Windows 2000 or later and Windows 98 or later.)

You can include AlphaBlend and TransparentBlt in an application that runs on Windows 95 or Windows NT 4.0 only if these methods never get called. If your application includes these methods, and it must run on earlier operating systems, you must use the linker's /delayload to delay the loading of msimg32.lib. As long as your application does not call one of these methods while running under Windows NT 4.0 or Windows 95, it will not attempt to load msimg32.lib. You can check the whether transparency support is available using the CImage::IsTransparencySupported method.

if (CImage::IsTransparencySupported())
{
   // Safe to call CImage::AlphaBlend and CImage::TransparentBlt
}
else
{
   // Transparency not supported.  Fall back to something else.
}

To compile an application that calls these methods, insert a #define _WIN32_WINNT statement before #including any system headers, indicating that the version of Windows is equal to or greater than 5.0:

#define _WIN32_WINNT 0x0501

If your application does not need to run on an operating system older than Windows 2000 or Windows 98, you can link directly to msimg32.lib without using /delayload.

CImage::Draw behaves differently when used with Windows 2000 and Windows 98 than it does with Windows NT 4.0 or Windows 95.

If you compile your application with _WIN32_WINNT set to a value less than 0x0500, Draw will work, but it will not handle transparency automatically on systems running Windows 2000 and Windows 98 and later.

If you compile your application with _WIN32_WINNT set to 0x0500 or greater, Draw will handle transparency automatically on systems running Windows 2000 or Windows 98 and later. It will also work, but without transparency support, with Windows NT 4.0 and Windows 95; however, you must use /delayload to delay the loading of msimg32.LIB, as described above for AlphaBlend and TransparentBlt.

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