SetPortPix
SetPortPix Replaces a portPixMap of the active CGrafPort with a handle
#include <Quickdraw.h> Color Quickdraw
void SetPortPix( pm );
PixMapHandle newPixMap ; handle to a portPixMap structure
SetPortPix replaces the portPixMap field of the active CGrafPort with a
new value, effectively changing the entire contents of the port.
Returns: none

Notes: This is the Color Quickdraw equivalent of the SetPortBits procedure that
QuickDraw uses on GrafPorts. SetPortPix cannot be used at all on
old-style GrafPorts. Conversely, a SetPortBits call used in conjunction
with a cGrafPort, will likewise yield nothing.
Like its predecessor, SetPortPix is useful for performing off- screen
drawing. For instance, you can use a series of Color Quickdraw calls to
create an image in an off-screen memory buffer, then use CopyBits to
copy the bit-mapped image into the normal screen.