How to identify & use OSType in Cocoa

In Cocoa/Mac OSX 10.6

OSType IOSurfaceGetPixelFormat(IOSurfaceRef buffer)

returns a type OSType

where can I find some documentation/reference on the supported OSType with regard to the context of this function.

What sort OSType should 开发者_StackOverflowI expect with IOSurfaceGetPixelFormat? do you have any ideas on the various expected values from this function?

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From MacTypes.h:

typedef FourCharCode     OSType;
typedef UInt32           FourCharCode;
typedef unsigned long    UInt32; //or unsigned int, depending on architecture

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Try the pixel format type constants defined in CVPixelBuffer.h in the Core Video framework. That header conditionally includes IOSurface.h; to me, that implies that they're related.

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Do keep in mind that IOSurface is little more than a friendly wrapper around shared memory. As such, IOSurfaceGetPixelFormat simply returns whatever was specified when the IOSurface was created, or 0 if no pixel format was specified.