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NAME

ReadPixel
read the pen number value of the pixel at a specified x,y location within a certain RastPort.

SYNOPSIS

penno = ReadPixel( rp, x, y )
d0 a1 d0:16 d1:16

LONG ReadPixel( struct RastPort *, SHORT, SHORT );

FUNCTION

Combine the bits from each of the bit-planes used to describe a particular RastPort into the pen number selector which that bit combination normally forms for the system hardware selection of pixel color.

INPUTS

rp
pointer to a RastPort structure

x
see next

y
a point in the RastPort

RESULT

penno
the pen number of the pixel at (x,y) is returned. -1 is returned if the pixel cannot be read for some reason.

SEE ALSO

WritePixel() graphics/rastport.h