1 .\" $NetBSD: appen.C,v 1.6 2002/10/01 19:06:39 wiz 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. All advertising materials mentioning features or use of this software 15 .\" must display the following acknowledgement: 16 .\" This product includes software developed by the University of 17 .\" California, Berkeley and its contributors. 18 .\" 4. Neither the name of the University nor the names of its contributors 19 .\" may be used to endorse or promote products derived from this software 20 .\" without specific prior written permission. 21 .\" 22 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 .\" SUCH DAMAGE. 33 .\" 34 .\" @(#)appen.C 8.1 (Berkeley) 6/8/93 35 .\" 36 .ie t .oh '\*(Ln Appendix A''PS1:19-%' 37 .eh 'PS1:19-%''\*(Ln Appendix A' 38 .el .he ''\fIAppendix A\fR'' 39 .bp 40 .(x 41 .ti 0 42 .b "Appendix A" 43 .)x 44 .sh 1 "Examples" 1 45 .pp 46 Here we present a few examples 47 of how to use the package. 48 They attempt to be representative, 49 though not comprehensive. 50 Further examples can be found in the games section 51 of the source tree and in various utilities that use the screen such as 52 .i systat(1) . 53 .sh 2 "Screen Updating" 54 .pp 55 The following examples are intended to demonstrate 56 the basic structure of a program 57 using the screen updating sections of the package. 58 Several of the programs require calculational sections 59 which are irrelevant of to the example, 60 and are therefore usually not included. 61 It is hoped that the data structure definitions 62 give enough of an idea to allow understanding 63 of what the relevant portions do. 64 .sh 3 "Simple Character Output" 65 .pp 66 This program demonstrates how to set up a window and output characters to it. 67 Also, it demonstrates how one might control the output to the window. 68 If you run this program, you will get a demonstration of the character output 69 chracteristics discussed in the above Character Output section. 70 .(l I 71 .so t2.gr 72 .)l 73 .sh 3 "A Small Screen Manipulator" 74 .pp 75 The next example follows the lines of the previous one but extends then to 76 demonstrate the various othe uses of the package. 77 Make sure you understand how this program works as it encompasses most of 78 anything you will need to do with the package. 79 .(l I 80 .so t3.gr 81 .)l 82 .sh 3 "Twinkle" 83 .pp 84 This is a moderately simple program which prints 85 patterns on the screen. 86 It switches between patterns of asterisks, 87 putting them on one by one in random order, 88 and then taking them off in the same fashion. 89 It is more efficient to write this 90 using only the motion optimization, 91 as is demonstrated below. 92 .(l I 93 .so twinkle1.gr 94 .)l 95 .sh 3 "Life" 96 .pp 97 This program fragment models the famous computer pattern game of life 98 (Scientific American, May, 1974). 99 The calculational routines create a linked list of structures 100 defining where each piece is. 101 Nothing here claims to be optimal, 102 merely demonstrative. 103 This code, however, 104 is a very good place to use the screen updating routines, 105 as it allows them to worry about what the last position looked like, 106 so you don't have to. 107 It also demonstrates some of the input routines. 108 .(l I 109 .so life.gr 110 .)l 111 .sh 2 "Motion optimization" 112 .pp 113 The following example shows how motion optimization 114 is written on its own. 115 Programs which flit from one place to another without 116 regard for what is already there 117 usually do not need the overhead of both space and time 118 associated with screen updating. 119 They should instead use motion optimization. 120 .sh 3 "Twinkle" 121 .pp 122 The 123 .b twinkle 124 program 125 is a good candidate for simple motion optimization. 126 Here is how it could be written 127 (only the routines that have been changed are shown): 128 .(l 129 .so twinkle2.gr 130 .)l 131