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Inside Macintosh: Interapplication Communication /

Chapter 4 - Responding to Apple Events / Reference to Responding to Apple Events

Routines for Responding to Apple Events / Getting Data and Keyword-Specified Descriptor Records Out of AE Records

AEGetKeyPtr

You can use the AEGetKeyPtr function to get a pointer to a buffer that contains the data from a keyword-specified descriptor record. You can use this function to get data from an AE record or an Apple event record.

FUNCTION AEGetKeyPtr (theAERecord: AERecord; 
                      theAEKeyword: AEKeyword; 
                      desiredType: DescType; 
                      VAR typeCode: DescType; 
                      dataPtr: Ptr; maximumSize: Size; 
                      VAR actualSize: Size): OSErr;

theAERecord

The AE record containing the desired data.

theAEKeyword

The keyword that specifies the desired descriptor record.

desiredType

The desired descriptor type for the data to be returned; if the requested data is not of this type, the Apple Event Manager attempts to coerce it to this type. If the value of desiredType is typeWildCard, no coercion is performed, and the descriptor type of returned data is the same as the descriptor type of the original data.

typeCode

The descriptor type of the returned data.

dataPtr

A pointer to the buffer for storing the data.

maximumSize

The maximum length, in bytes, of the data to be returned. You must allocate at least this amount of storage for the buffer specified by the dataPtr parameter.

actualSize

The length, in bytes, of the data for the keyword-specified descriptor record. If this value is larger than the value of the maximumSize parameter, not all of the data for the parameter was returned.

DESCRIPTION

The AEGetKeyPtr function uses a buffer to return the data from a keyword-specified Apple event parameter, which the function attempts to coerce to the descriptor type specified by the desiredType parameter.

RESULT CODES

noErr	0	No error
memFullErr	-108	Not enough room in heap zone
errAECoercionFail	-1700	Data could not be coerced to the requested descriptor type
errAEDescNotFound	-1701	Descriptor record was not found
errAEWrongDataType	-1703	Wrong descriptor type
errAENotAEDesc	-1704	Not a valid descriptor record
errAEReplyNotArrived	-1718	Reply has not yet arrived