Maps a point in one rectangle to an equivalent position in another rectangle.

void MapPt (
    Point *pt, 
    const Rect *srcRect, 
    const Rect *dstRect
);

Parameter descriptions

pt

Upon input, a pointer to the point in the source rectangle to map; upon completion, a pointer to its mapped position in the destination rectangle.

srcRect

The source rectangle containing the original point.

dstRect

The destination rectangle in which the point will be mapped.

DISCUSSION

The MapPt function maps a point in one rectangle to an equivalent position in another rectangle.

In the pt parameter, you specify a point that lies within the rectangle that you specify in the srcRect parameter. The MapPt function maps this point to a similarly located point within the rectangle that you specify in the dstRect parameter—that is, to where it would fall if it were part of a drawing being expanded or shrunk to fit the destination rectangle. The MapPt function returns the location of the mapped point in the pt parameter. For example, a corner point of the source rectangle would be mapped to the corresponding corner point of the destination rectangle in dstRect, and the center of the source rectangle would be mapped to the center of destination rectangle.

The source and destination rectangles may overlap, and the point you specify need not actually lie within the source rectangle.

If you are going to draw inside the destination rectangle, you’ll probably also want to scale the graphics pen size accordingly with ScalePt.

SPECIAL CONSIDERATIONS

If the points or rectangles supplied to this function are defined in a graphics port other than your current graphics port, you must convert them to the local coordinate system of your current graphics port. You can accomplish this by using the SetPort function to change to the graphics port containing the points or rectangles, using the LocalGlobal function to convert their locations to global coordinates, using SetPort to return to your starting graphics port, and then using the GlobalToLocal function to convert the locations of points or rectangles to the local coordinates of your current graphics port.

AVAILABILITY

Supported in Carbon. Available in Carbon 1.0.2 and later when running Mac OS 8.1 or later.

© 2000 Apple Computer, Inc. (Last Updated 6/30/2000)