1 .\" $NetBSD: appen.C,v 1.7 2003/08/07 16:44:26 agc Exp $ 2 .\" 3 .\" Copyright (c) 1980, 1993 4 .\" The Regents of the University of California. All rights reserved. 5 .\" 6 .\" Redistribution and use in source and binary forms, with or without 7 .\" modification, are permitted provided that the following conditions 8 .\" are met: 9 .\" 1. Redistributions of source code must retain the above copyright 10 .\" notice, this list of conditions and the following disclaimer. 11 .\" 2. Redistributions in binary form must reproduce the above copyright 12 .\" notice, this list of conditions and the following disclaimer in the 13 .\" documentation and/or other materials provided with the distribution. 14 .\" 3. Neither the name of the University nor the names of its contributors 15 .\" may be used to endorse or promote products derived from this software 16 .\" without specific prior written permission. 17 .\" 18 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 .\" SUCH DAMAGE. 29 .\" 30 .\" @(#)appen.C 8.1 (Berkeley) 6/8/93 31 .\" 32 .ie t .oh '\*(Ln Appendix A''PS1:19-%' 33 .eh 'PS1:19-%''\*(Ln Appendix A' 34 .el .he ''\fIAppendix A\fR'' 35 .bp 36 .(x 37 .ti 0 38 .b "Appendix A" 39 .)x 40 .sh 1 "Examples" 1 41 .pp 42 Here we present a few examples 43 of how to use the package. 44 They attempt to be representative, 45 though not comprehensive. 46 Further examples can be found in the games section 47 of the source tree and in various utilities that use the screen such as 48 .i systat(1) . 49 .sh 2 "Screen Updating" 50 .pp 51 The following examples are intended to demonstrate 52 the basic structure of a program 53 using the screen updating sections of the package. 54 Several of the programs require calculational sections 55 which are irrelevant of to the example, 56 and are therefore usually not included. 57 It is hoped that the data structure definitions 58 give enough of an idea to allow understanding 59 of what the relevant portions do. 60 .sh 3 "Simple Character Output" 61 .pp 62 This program demonstrates how to set up a window and output characters to it. 63 Also, it demonstrates how one might control the output to the window. 64 If you run this program, you will get a demonstration of the character output 65 chracteristics discussed in the above Character Output section. 66 .(l I 67 .so t2.gr 68 .)l 69 .sh 3 "A Small Screen Manipulator" 70 .pp 71 The next example follows the lines of the previous one but extends then to 72 demonstrate the various othe uses of the package. 73 Make sure you understand how this program works as it encompasses most of 74 anything you will need to do with the package. 75 .(l I 76 .so t3.gr 77 .)l 78 .sh 3 "Twinkle" 79 .pp 80 This is a moderately simple program which prints 81 patterns on the screen. 82 It switches between patterns of asterisks, 83 putting them on one by one in random order, 84 and then taking them off in the same fashion. 85 It is more efficient to write this 86 using only the motion optimization, 87 as is demonstrated below. 88 .(l I 89 .so twinkle1.gr 90 .)l 91 .sh 3 "Life" 92 .pp 93 This program fragment models the famous computer pattern game of life 94 (Scientific American, May, 1974). 95 The calculational routines create a linked list of structures 96 defining where each piece is. 97 Nothing here claims to be optimal, 98 merely demonstrative. 99 This code, however, 100 is a very good place to use the screen updating routines, 101 as it allows them to worry about what the last position looked like, 102 so you don't have to. 103 It also demonstrates some of the input routines. 104 .(l I 105 .so life.gr 106 .)l 107 .sh 2 "Motion optimization" 108 .pp 109 The following example shows how motion optimization 110 is written on its own. 111 Programs which flit from one place to another without 112 regard for what is already there 113 usually do not need the overhead of both space and time 114 associated with screen updating. 115 They should instead use motion optimization. 116 .sh 3 "Twinkle" 117 .pp 118 The 119 .b twinkle 120 program 121 is a good candidate for simple motion optimization. 122 Here is how it could be written 123 (only the routines that have been changed are shown): 124 .(l 125 .so twinkle2.gr 126 .)l 127