Legacy Document

Inside Macintosh: Imaging With QuickDraw /

Chapter 2 - Basic QuickDraw / Basic QuickDraw Reference

Routines / Manipulating Points in Graphics Ports

SubPt

To subtract the coordinates of one point from another, you can use the SubPt procedure.

PROCEDURE SubPt (srcPt:\xDDPoint; VAR dstPt:\xDDPoint);

srcPt

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

dstPt

On input: a point, from whose coordinates are to be subtracted those specified in the srcPt parameter. Upon completion: the result of subtracting the coordinates of the points in the srcPt parameter from the coordinates of the points in the dstPt parameter.

DESCRIPTION

The SubPt procedure subtracts the coordinates of the point specified in the srcPt parameter from the coordinates of the point specified in the dstPt parameter, and returns the result in the dstPt parameter.

To get the results of coordinate subtraction returned as a function result, you can instead use the DeltaPoint function. Note, however, that the parameters in these two routines are reversed.