Value Setting Function

The function that you call to send the interpolated value to the receiving track is defined as a universal procedure in systems that support the Code Fragment Manager (CFM) or defined as a data procedure for non-CFM systems:



 
typedef UniversalProcPtr TweenerDataUPP;    /* CFM */



 
typedef TweenerDataProcPtr TweenerDataUPP;  /* non-CFM */

The TweenerDataUPP function pointer specifies the function the tween component calls with the value generated by the tween operation. A tween component calls this function from its implementation of the TweenerDoTween function.



 
typedef pascal ComponentResult (*TweenerDataProcPtr)(

                     TweenRecord *tr,

                     void *tweenData,

                     long tweenDataSize,

                     long dataDescriptionSeed,

                     Handle dataDescription,

                     ICMCompletionProcRecordPtr asyncCompletionProc,

                     ProcPtr transferProc,

                     void *refCon);

tr: Contains a pointer to the tween record for the tween operation.
tweenData: Contains a pointer to the generated tween value.
tweenDataSize: Specifies the size, in bytes, of the tween value.
dataDescriptionSeed: Specifies the starting value for the calculation. Every time the content of the dataDescription handle changes, this value should be incremented.
dataDescription: Specifies a handle containing a description of the tween value passed. For basic types such as integers, the calling tween component should set this parameter to nil . For more complex types such as compressed image data, the calling tween component should set this handle to contain a description of the tween value, such as an image description.
asyncCompletionProc: Contains a pointer to a completion procedure for asynchronous operations. The calling tween component should set the value of this parameter to nil .
transferProc: Contains a pointer to a procedure to transfer the data. The calling tween component should set the value of this parameter to nil .
refCon: Contains a pointer to a reference constant. The calling tween component should set the value of this parameter to nil .

DISCUSSION

You call this function by invoking the function specified in the tween record's dataProc field.

RESULT CODES

`noErr`	0	No error
`paramErr`	-50	Invalid parameter specified

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