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CMCheckPixMap |
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Header: | CMMComponent.h | Carbon status: | Unsupported | |
Handles the kCMMCheckPixMap request by checking the colors of the specified pixel map image against the color gamut of the destination profile.
CMCheckPixMap ();
A CMM should respond to the kCMMCheckPixMap request code, but it is not required to do so. The ColorSync Manager sends this request code to your CMM on behalf of an application that called the CWCheckPixMap function. The ColorSync Manager dispatches this request to the Component Manager, which calls your CMM to service the request. A CMM typically responds to the kCMMCheckPixMap request code by calling a CMM-defined function (for example, CMCheckPixMap) to handle the request.
If your CMM supports this request code, your CMCheckPixMap function should be prepared to receive any of the pixel map types defined by QuickDraw.Your CMCheckPixMap function must check the colors of the pixel map image pointed to by the myPixMap parameter against the color gamut of the destination profile to determine if the colors are within the gamut. If a pixel color of the pixel map indicated by myPixMap is out of gamut, your function must set to 1 the corresponding pixel of the bitmap indicated by myBitMap. The ColorSync Manager returns the bitmap showing the gamut check results to the calling application or device driver.
Before the Component Manager calls your CMM with a ColorSync request to check the colors of a pixel map, it calls your CMM with a kNCMMInit or kCMMConcatInit request. Your CMM sets up the destination profile information during initialization in response to the kNCMMInit or kCMMConcatInit request code.
When the Component Manager calls your CMM with the kCMMCheckPixMap request code, it passes to your CMM in the session parameter a handle to your CMMs private storage for the calling applications component instance. Your CMCheckPixMap function should use the profile data you set in your storage for this component instance. If you used some other method to store profile data for this component instance when you initialized the session, you should obtain the profile data you require for the color-checking process from that storage.
Your CMMatchPixMap function must call the progress function supplied by the calling application or device driver at regular intervals to allow it to report progress to the user on the color-checking session. Your CMCheckPixMap function should monitor the progress function for a returned value of true, which indicates that the user interrupted the color-checking process. In this case, you should terminate the color-checking process. The default CMM calls the progress function approximately every half-second, unless color checking takes less time; this happens when there is a small amount of data to match.
Each time your CMCheckPixMap function calls the CMBitmapCallBackProcPtr function, it must pass to the function any data stored in the reference constant. When the Component Manager called your CMM with the kCMMCheckPixMap request code, it passed to your CMM the reference constant from the calling program.
Each time your function calls the CMBitmapCallBackProcPtr function, your function must pass it a byte count in the progress parameter identifying the remaining number of bytes to check. As your CMCheckPixMap function checks the pixels of the myPixMap map, it should set the corresponding pixel of myBitMap to 0 if the color is in gamut and 1 if it is out of gamut. The last time your CMCheckPixMap function calls the CMBitmapCallBackProcPtr function, it must pass a byte count of 0 to indicate the completion of the color-checking process, signaling the progress function to perform any cleanup operations it requires.
The data color space of a pixel map is implicitly RGB. If the source and destination profiles data color spaces (dataColorSpace field) are not also RGB, your function should not perform the color check. Instead, it should return an error.
If your CMM does not support a pixel map type that you receive, you can return an unimplemented error. In this case, the ColorSync Manager unpacks the colors of the pixel map and calls your CMMatchColors function, passing it the pixel map colors in a color list. You should avoid defaulting to this behavior, if possible, because it incurs overhead and slows down performance.
CMCheckPixMap is an API to CMMs. Use CWCheckPixMap instead. Application developers should avoid calling CMMs directly, since they may or may not support a given API.
© 2000 Apple Computer, Inc. (Last Updated 7/17/2000)