Begins creating a new region

NewRgn ();

function result

A handle to the new region.

DISCUSSION

The NewRgn function allocates space for a new, variable-size region and initializes it to the empty region defined by the rectangle (0,0,0,0). This is the only function that creates a new region; other functions merely alter the size or shape of existing regions.

To begin defining a region, use the OpenRgn function.

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.

SPECIAL CONSIDERATIONS

The NewRgn function may move or purge memory blocks in the application heap; do not call this function at interrupt time.

Use the Memory Manager function MaxMem to determine whether the memory for the region is valid before using NewRgn.

Ensure that the memory for a region is valid before calling this function to manipulate that region; if there isn’t sufficient memory, the system may crash. Regions are limited to 32 KB in size in basic QuickDraw and 64 KB in color QuickDraw. Before defining a region, you can use the Memory Manager function MaxMem to determine whether the memory for the region is valid. You can determine the current size of an existing region by calling the Memory Manager function GetHandleSize. When you record drawing operations in an open region, the resulting region description may overflow the 32 KB or 64 KB limit. Should this happen in color QuickDraw, the QDError function returns the result code regionTooBigError.

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)