131 lines
4.7 KiB
C
131 lines
4.7 KiB
C
.\" $NetBSD: appen.C,v 1.6 2002/10/01 19:06:39 wiz Exp $
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.\"
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.\" Copyright (c) 1980, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)appen.C 8.1 (Berkeley) 6/8/93
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.\"
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.ie t .oh '\*(Ln Appendix A''PS1:19-%'
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.eh 'PS1:19-%''\*(Ln Appendix A'
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.el .he ''\fIAppendix A\fR''
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.bp
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.(x
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.ti 0
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.b "Appendix A"
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.)x
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.sh 1 "Examples" 1
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.pp
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Here we present a few examples
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of how to use the package.
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They attempt to be representative,
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though not comprehensive.
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Further examples can be found in the games section
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of the source tree and in various utilities that use the screen such as
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.i systat(1) .
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.sh 2 "Screen Updating"
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.pp
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The following examples are intended to demonstrate
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the basic structure of a program
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using the screen updating sections of the package.
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Several of the programs require calculational sections
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which are irrelevant of to the example,
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and are therefore usually not included.
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It is hoped that the data structure definitions
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give enough of an idea to allow understanding
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of what the relevant portions do.
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.sh 3 "Simple Character Output"
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.pp
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This program demonstrates how to set up a window and output characters to it.
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Also, it demonstrates how one might control the output to the window.
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If you run this program, you will get a demonstration of the character output
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chracteristics discussed in the above Character Output section.
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.(l I
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.so t2.gr
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.)l
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.sh 3 "A Small Screen Manipulator"
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.pp
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The next example follows the lines of the previous one but extends then to
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demonstrate the various othe uses of the package.
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Make sure you understand how this program works as it encompasses most of
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anything you will need to do with the package.
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.(l I
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.so t3.gr
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.)l
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.sh 3 "Twinkle"
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.pp
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This is a moderately simple program which prints
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patterns on the screen.
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It switches between patterns of asterisks,
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putting them on one by one in random order,
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and then taking them off in the same fashion.
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It is more efficient to write this
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using only the motion optimization,
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as is demonstrated below.
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.(l I
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.so twinkle1.gr
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.)l
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.sh 3 "Life"
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.pp
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This program fragment models the famous computer pattern game of life
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(Scientific American, May, 1974).
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The calculational routines create a linked list of structures
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defining where each piece is.
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Nothing here claims to be optimal,
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merely demonstrative.
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This code, however,
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is a very good place to use the screen updating routines,
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as it allows them to worry about what the last position looked like,
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so you don't have to.
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It also demonstrates some of the input routines.
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.(l I
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.so life.gr
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.)l
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.sh 2 "Motion optimization"
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.pp
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The following example shows how motion optimization
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is written on its own.
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Programs which flit from one place to another without
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regard for what is already there
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usually do not need the overhead of both space and time
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associated with screen updating.
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They should instead use motion optimization.
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.sh 3 "Twinkle"
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.pp
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The
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.b twinkle
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program
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is a good candidate for simple motion optimization.
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Here is how it could be written
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(only the routines that have been changed are shown):
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.(l
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.so twinkle2.gr
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.)l
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