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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <gki.h>
include "imd.h"
define DEF_YRES 8192 # default height of device pixel in GKI units
define ZSTEP 4 # bit to be tested (step function width)
# IMD_PUTCELLARRAY -- Draw a cell array, i.e., two dimensional array of pixels
# (greylevels or colors). The algorithm used here maps 8 bits in into 1 bit
# out, using a step function lookup table. The result is a band-contoured
# image, where the spacing and width of the contour bands decreases as the
# rate of change of intensity in the input cell array increases.
procedure imd_putcellarray (m, nx, ny, ax1,ay1, ax2,ay2)
short m[nx,ny] # cell array
int nx, ny # number of pixels in X and Y
int ax1, ay1 # lower left corner of output window
int ax2, ay2 # upper right corner of output window
bool ttygetb()
include "imd.com"
begin
if (ttygetb (g_tty, "BI"))
call imd_bcell (m, nx, ny, ax1,ay1, ax2,ay2)
else
call imd_mcell (m, nx, ny, ax1,ay1, ax2,ay2)
end
# IMD_BCELL -- Put cell array, optimized for a bitmap device. In this case,
# to get the maximum resolution at maximum efficiency it is desirable for the
# main loop to be over device pixels, mapping the device pixel into the
# nearest line of the input cell array.
procedure imd_bcell (m, nx, ny, ax1,ay1, ax2,ay2)
short m[nx,ny] # cell array
int nx, ny # number of pixels in X and Y
int ax1, ay1 # lower left corner of output window
int ax2, ay2 # upper right corner of output window
real dx, dy
int my, i1, i2, v, i, j, k
include "imd.com"
int and()
begin
# Count drawing instruction, set polyline width to 1 for max y-res.
g_ndraw = g_ndraw + 1
call idk_linewidth (g_out, 1)
IMD_WIDTH(g_kt) = 0
# Determine the width of a cell array pixel in GKI units.
dx = real (ax2 - ax1) / nx
# Determine the height of a device pixel in GKI units.
if (IMD_YRES(g_kt) <= 0)
dy = GKI_MAXNDC / DEF_YRES
else
dy = max (1.0, real(GKI_MAXNDC) / real(IMD_YRES(g_kt)))
# Process the cell array. The outer loop runs over device pixels in Y;
# each iteration writes one line of the output raster. The inner loop
# runs down a line of the cell array.
k = 0
for (my = ay1 + dy/2; my < ay2; my = k * dy + ay1) {
j = max(1, min(ny, int (real(my-ay1) / real(ay2-ay1) * (ny-1)) + 1))
my = min (my, int (ay2 - dy/2))
for (i=1; i <= nx; ) {
do i = i, nx {
v = m[i,j]
if (and (v, ZSTEP) != 0)
break
}
if (i <= nx) {
i1 = i
i2 = nx
do i = i1 + 1, nx {
v = m[i,j]
if (and (v, ZSTEP) == 0) {
i2 = i
break
}
}
# The following decreases the length of dark line segments
# to make features more visible.
if (i2 - i1 >= 2)
if (i1 > 1 && i2 < nx) {
i1 = i1 + 1
i2 = i2 - 1
}
# Draw the line segment.
call idk_move (g_out, int ((i1-1) * dx + ax1), my)
call idk_draw (g_out, int (i2 * dx + ax1), my)
if (i2 >= nx)
i = nx + 1
}
}
k = k + 1
}
end
# IMD_MCELL -- Put cell array, optimized for a metafile device. In this case,
# it is prohibitively expensive to draw into each resolvable line of the
# output device. It is better to set the linewidth to the width of a cell
# array pixel, output the minimum number of drawing instructions, and let the
# metafile device widen the lines.
procedure imd_mcell (m, nx, ny, ax1,ay1, ax2,ay2)
short m[nx,ny] # cell array
int nx, ny # number of pixels in X and Y
int ax1, ay1 # lower left corner of output window
int ax2, ay2 # upper right corner of output window
real dx, dy
int yres, my, i1, i2, v, i, j
include "imd.com"
int and()
begin
# Count drawing instruction, clobber saved polyline width.
g_ndraw = g_ndraw + 1
IMD_WIDTH(g_kt) = 0
# Determine the width and height of a cell array pixel in GKI units.
dx = real (ax2 - ax1) / nx
dy = real (ay2 - ay1) / ny
# Set the IDK line width to the height of a pixel in the cell array.
yres = IMD_YRES(g_kt)
if (yres <= 0)
yres = DEF_YRES
call idk_linewidth (g_out,
max (1, nint (dy / (real(GKI_MAXNDC) / real(yres)))))
# Process the cell array. The outer loop runs over lines of the input
# cell array; each iteration writes only one line of the output raster,
# but the width of the line is adjusted to the height of a pixel in
# the cell array (the resolution of the cell array should not exceed
# that of the device).
for (j=1; j <= ny; j=j+1) {
my = int ((j - 0.5) * dy) + ay1
for (i=1; i <= nx; ) {
do i = i, nx {
v = m[i,j]
if (and (v, ZSTEP) != 0)
break
}
if (i <= nx) {
i1 = i
i2 = nx
do i = i + 1, nx {
v = m[i,j]
if (and (v, ZSTEP) == 0) {
i2 = i
break
}
}
# The following decreases the length of dark line segments
# to make features more visible.
if (i2 - i1 >= 2)
if (i1 > 1 && i2 < nx) {
i1 = i1 + 1
i2 = i2 - 1
}
# Draw the line segment.
call idk_move (g_out, int ((i1-1) * dx + ax1), my)
call idk_draw (g_out, int (i2 * dx + ax1), my)
if (i2 >= nx)
i = nx + 1
}
}
}
end
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