17. 绘制显示器能力图

#!/bin/sh
#
# modeplot -- generate X mode plot of available monitor modes
#
# Do `modeplot -?' to see the control options.
#

# Monitor description. Bandwidth in MHz, horizontal frequencies in kHz
# and vertical frequencies in Hz.
TITLE="Viewsonic 21PS"
BANDWIDTH=185
MINHSF=31
MAXHSF=85
MINVSF=50
MAXVSF=160
ASPECT="4/3"
vesa=72.5	# VESA-recommended minimum refresh rate

while [ "$1" != "" ] 
do
	case $1 in
	-t) TITLE="$2"; shift;; 
	-b) BANDWIDTH="$2"; shift;; 
	-h) MINHSF="$2" MAXHSF="$3"; shift; shift;; 
	-v) MINVSF="$2" MAXVSF="$3"; shift; shift;; 
	-a) ASPECT="$2"; shift;; 
	-g) GNUOPTS="$2"; shift;; 
	-?) cat <<EOF
modeplot control switches:

-t "<description>"	name of monitor            defaults to "Viewsonic 21PS"
-b <nn>           	bandwidth in MHz           defaults to 185
-h <min> <max>   	min & max HSF (kHz)        defaults to 31 85
-v <min> <max>   	min & max VSF (Hz)         defaults to 50 160
-a <aspect ratio>	aspect ratio               defaults to 4/3
-g "<options>"   	pass options to gnuplot

The -b, -h and -v options are required, -a, -t, -g optional.  You can
use -g to pass a device type to gnuplot so that (for example) modeplot's
output can be redirected to a printer.  See gnuplot(1) for  details.

The modeplot tool was created by Eric S. Raymond <esr@thyrsus.com> based on
analysis and scratch code by Martin Lottermoser <Martin.Lottermoser@mch.sni.de>

This is modeplot $Revision: 1.27 $
EOF
		exit;;
	esac
	shift
done

gnuplot $GNUOPTS <<EOF
set title "$TITLE Mode Plot"

# Magic numbers.  Unfortunately, the plot is quite sensitive to changes in
# these, and they may fail to represent reality on some monitors.  We need
# to fix values to get even an approximation of the mode diagram.  These come
# from looking at lots of values in the ModeDB database.
F1 = 1.30	# multiplier to convert horizontal resolution to frame width
F2 = 1.05	# multiplier to convert vertical resolution to frame height

# Function definitions (multiplication by 1.0 forces real-number arithmetic)
ac = (1.0*$ASPECT)*F1/F2
refresh(hsync, dcf) = ac * (hsync**2)/(1.0*dcf)
dotclock(hsync, rr) = ac * (hsync**2)/(1.0*rr)
resolution(hv, dcf) = dcf * (10**6)/(hv * F1 * F2)

# Put labels on the axes
set xlabel 'DCF (MHz)'
set ylabel 'RR (Hz)' 6	# Put it right over the Y axis

# Generate diagram
set grid
set label "VB" at $BANDWIDTH+1, ($MAXVSF + $MINVSF) / 2 left
set arrow from $BANDWIDTH, $MINVSF to $BANDWIDTH, $MAXVSF nohead
set label "max VSF" at 1, $MAXVSF-1.5
set arrow from 0, $MAXVSF to $BANDWIDTH, $MAXVSF nohead
set label "min VSF" at 1, $MINVSF-1.5
set arrow from 0, $MINVSF to $BANDWIDTH, $MINVSF nohead
set label "min HSF" at dotclock($MINHSF, $MAXVSF+17), $MAXVSF + 17 right
set label "max HSF" at dotclock($MAXHSF, $MAXVSF+17), $MAXVSF + 17 right
set label "VESA $vesa" at 1, $vesa-1.5
set arrow from 0, $vesa to $BANDWIDTH, $vesa nohead # style -1
plot [dcf=0:1.1*$BANDWIDTH] [$MINVSF-10:$MAXVSF+20] \
  refresh($MINHSF, dcf) notitle with lines 1, \
  refresh($MAXHSF, dcf) notitle with lines 1, \
  resolution(640*480,   dcf) title "640x480  " with points 2, \
  resolution(800*600,   dcf) title "800x600  " with points 3, \
  resolution(1024*768,  dcf) title "1024x768 " with points 4, \
  resolution(1280*1024, dcf) title "1280x1024" with points 5, \
  resolution(1600*1280, dcf) title "1600x1200" with points 6

pause 9999
EOF

	RR = DCF / (HFL * VFL)		(*)

	HFL = DCF / HSF			(**)

	VFL = F2 * VR
	    = F2 * (HR / AR)
	    = (F2/F1) * HFL / AR	(***)

	RR = DCF / ((F2/F1) * HFL**2 / AR)
	   = (F1/F2) * AR * DCF * (HSF/DCF)**2
	   = (F1/F2) * AR * HSF**2 / DCF

	RR = DCF / (HFL * VFL) = DCF / (F1 * HR * F2 * VR)

	modeplot -t "Swan SW617" -b 85 -v 50 90 -h 31 58