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Inside Macintosh: Imaging With QuickDraw /

Chapter 2 - Basic QuickDraw / Basic QuickDraw Reference

Routines / Manipulating Points in Graphics Ports

DeltaPoint

To subtract the coordinates of one point from another, you can use the DeltaPoint function.

FUNCTION DeltaPoint (ptA:\xDDPoint; ptB:\xDDPoint): LongInt;

ptA

A point, from whose coordinates are to be subtracted those specified in the ptB parameter.

ptB

A point, the coordinates of which are to be subtracted from those specified in the ptA parameter.

DESCRIPTION

The DeltaPoint function subtracts the coordinates of the point specified in the ptB parameter from the coordinates of the point specified in the ptA parameter, and returns the result as its function result.

To get the results of coordinate subtraction, you can instead use the SubPt procedure. Note, however, that the parameters in these two routines are reversed.