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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <gio.h>
# GGCELL -- Get a cell array, i.e., a two dimensional array of pixels. If the
# resolution of the graphics device does not match that of the cell array the
# kernel is expected to compute the coordinates of each cell array pixel in
# device coordinates and return the value of the nearest device pixel as the
# cell array value. This equates to either subsampling or block replication
# depending on the relative scale of the two devices. See put cell array for
# additional information.
procedure ggcell (gp, m, nx, ny, x1, y1, x2, y2)
pointer gp # device descriptor
int nx, ny # size of pixel array
short m[nx,ny] # pixels
real x1, y1 # lower left corner of input window
real x2, y2 # upper right corner of input window
real dy
int ly1, ly2, i
int sx1, sx2, sy1, sy2
include "gpl.com"
begin
# Flush any buffered polyline output. Make sure the wcs transformation
# in the cache is up to date.
if (op > 1)
call gpl_flush()
else if (gp != gp_out || GP_WCS(gp) != wcs)
call gpl_cache (gp)
# Transform cell window to GKI coordinates. The coordinate
# transformation must be linear.
sx1 = (x1 - wxorigin) * xscale + mxorigin
sx2 = (x2 - wxorigin) * xscale + mxorigin
sy1 = (y1 - wyorigin) * yscale + myorigin
sy2 = (y2 - wyorigin) * yscale + myorigin
dy = real (sy2 - sy1) / ny # height of a line in GKI coords
# Read the cell array into M, one line at a time. Take care that the
# GKI integer value of ly1 of one line is the same as the ly2 value
# of the previous line, or there will be a blank line in the output
# image.
do i = 1, ny {
ly1 = (i-1) * dy + sy1
ly2 = (i ) * dy + sy1
call gki_getcellarray (GP_FD(gp), m[1,i], nx,1, sx1,ly1, sx2,ly2)
}
end
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