MapRgn

Scale and reposition a region

#include <Quickdraw.h> Quickdraw

void MapRgn(theRgn, srcRect, destRect );

RgnHandle theRgn ; handle leading to region to map

Rect *srcRect ; address of Rect to convert from

Rect *destRect ; address of Rect to convert to

MapRgn resizes and re positions a region, converting its coordinates by a size

ratio and offset of two rectangles. Use this to scale and reposition a region.

theRgn is a handle leading to a variable-length Region structure. On entry,

it describes a region within srcRect that you wish to remap. Upon

return, all its coordinates have been recalculated relative to the size

and position of destRect .

destRect are the addresses of two 8-byte Rect structures. For typical

operations, theRgn is enclosed by srcRect . It gets mapped to a

similar position within destRect .

Notes: Use this function to resize and reposition a region that you wish to expand

or shrink as you move it from one rectangular area to another (typically

smaller or larger) one:

theRgn is expanded or shrunk by the ratio of the sizes of srcRect and

destRect. It is moved to a similarly-located position within destRect . This

is a purely mathematical operation and has no effect on the screen unless

theRgn is subsequently drawn or filled.

This function is preferable to InsetRgn since the region retains its shape,

scaled by the ratio of the rectangles. No information is lost; the region may

be remapped back to its original size.

Referenced by (6):