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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <syserr.h>
include <mach.h>
include <gio.h>
include <fset.h>
include <gescape.h>
# GIM_READPIXELS -- Read from a rectangular region of a raster.
procedure gim_readpixels (gp, raster, data, nbits, x1, y1, nx, ny)
pointer gp #I graphics descriptor
int raster #I raster number (0 is display window)
short data[ARB] #O returned pixel data
int nbits #I nbits per raster pixel (1,8,16,32)
int x1, y1 #I first pixel to be written
int nx, ny #I size of region to be written
int npix, nchars, nwords
short gim[GIM_READPIXELS_LEN]
short retval[GIM_RET_RPIX_LEN]
errchk gpl_flush, gflush, read, syserrs
string s_readpixels "gim_readpixels"
int read()
begin
call gpl_flush()
npix = nx * ny
nchars = (npix * nbits / NBITS_BYTE + SZB_CHAR-1) / SZB_CHAR
nwords = (nchars + SZ_SHORT-1) / SZ_SHORT
gim[GIM_READPIXELS_RN] = raster
gim[GIM_READPIXELS_EC] = 0
gim[GIM_READPIXELS_X1] = x1
gim[GIM_READPIXELS_Y1] = y1
gim[GIM_READPIXELS_NX] = nx
gim[GIM_READPIXELS_NY] = ny
gim[GIM_READPIXELS_BP] = nbits
call gki_escape (gp, GIM_READPIXELS, gim, GIM_READPIXELS_LEN)
call flush (GP_FD(gp))
# Get return value instruction header.
nchars = GIM_RET_RPIX_LEN * SZ_SHORT
if (read (GP_FD(gp), retval, nchars) != nchars) {
call fseti (GP_FD(gp), F_CANCEL, OK)
call syserrs (SYS_FREAD, s_readpixels)
}
# Get the pixel data.
npix = retval[GIM_RET_RPIX_NP]
nchars = (npix * nbits / NBITS_BYTE + SZB_CHAR-1) / SZB_CHAR
if (read (GP_FD(gp), data, nchars) != nchars) {
call fseti (GP_FD(gp), F_CANCEL, OK)
call syserrs (SYS_FREAD, s_readpixels)
}
call fseti (GP_FD(gp), F_CANCEL, OK)
if (npix != nx * ny)
call syserrs (SYS_IMNOPIX, s_readpixels)
end
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