Creates an offscreen PixMap structure and allocates memory for the base address of its pixel image.

QDErr NewScreenBuffer (
    const Rect *globalRect, 
    Boolean purgeable, 
    GDHandle *gdh, 
    PixMapHandle *offscreenPixMap
);

Parameter descriptions

globalRect

The boundary rectangle, in global coordinates, for the offscreen pixel map.

purgeable

A value of TRUE to make the memory block for the offscreen pixel map purgeable, or a value of FALSE to make it unpurgeable.

gdh

On return, a pointer to the handle to the GDevice structure for the graphics device with the greatest pixel depth among all graphics devices whose boundary rectangles intersect the rectangle specified in the globalRect parameter.

offscreenPixMap

On return, a pointer to a handle to the new offscreen PixMap structure.

DISCUSSION

Applications generally do not need to use NewScreenBuffer. The NewGWorld function uses the NewScreenBuffer function to create and allocate memory for an offscreen pixel image.

SPECIAL CONSIDERATIONS

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

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)