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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 or Descriptor Records Out of Apple Event Parameters and Attributes

AEGetParamPtr

You can use the AEGetParamPtr function to get a pointer to a buffer that contains the data from a specified Apple event parameter.

FUNCTION AEGetParamPtr (theAppleEvent: AppleEvent; 
                        theAEKeyword: AEKeyword;
                        desiredType: DescType; 
                        VAR typeCode: DescType; dataPtr: Ptr; 
                        maximumSize: Size; 
                        VAR actualSize: Size): OSErr;

theAppleEvent

The Apple event containing the desired parameter.

theAEKeyword

The keyword that specifies the desired parameter.

desiredType

The desired descriptor type for the data to be returned; if the requested Apple event parameter 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 the returned data is the same as the descriptor type of the Apple event parameter.

typeCode

The descriptor type of the returned data.

dataPtr

A pointer to the buffer in which the returned data is stored.

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 specified Apple event parameter. If this value is larger than the value of the maximumSize parameter, not all of the data for the parameter was returned.

DESCRIPTION

The AEGetParamPtr function uses a buffer to return the data from a specified Apple event parameter, which it 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

SEE ALSO

For examples of the use of AEGetParamPtr, see "Getting Data Out of an Apple Event," which begins on page 4-25.