programming/tads3/library/contributions/T3checks.t

#charset "us-ascii"

/*
** T3Checks helps you keep track of what capabilities a given
** interpreter has or doesn't have. For example: is the interpreter
** capable of HTML mode? Can the interpreter handle graphics?
** All results are stored in the sysInfoObj object.
**
** Version: 1.0 (6 Jan 2003)
**
** Copyright (c) 2003, Stephen Granade. All rights reserved.
**
*/

#include <tadsio.h>
#include <tadsgen.h>

// To use: in your main() function, call sysInfoObject.getSysInfo().
// The object is transient because we don't want its state saved in
// a game file, nor do we want it restored. This way, if the player
// plays our game on one machine, then moves the saved game file to
// another, the information won't be wrong.
transient sysInfoObject: object
    isHTMLRuntime = nil
    canDoGraphics = nil
    canDoSoundFX = nil
    canDoMusic = nil
    versionNumber = ''

    // graphicsOn() returns true if user has the "graphics" option selected
    //  and the runtime is capable of displaying graphics
    graphicsOn() {
	return (canDoGraphics && systemInfo(SysInfoPrefImages));
    }
    // soundsOn() is like graphicsOn(), only for sound effects
    soundsOn() {
	return (canDoSoundFX && systemInfo(SysInfoPrefSounds));
    }
    // And a similar function for music
    musicOn() {
	return (canDoMusic && systemInfo(SysInfoPrefMusic));
    }
    getSysInfo() {
	isHTMLRuntime = (systemInfo(SysInfoInterpClass) == SysInfoIClassHTML);
	canDoGraphics = (systemInfo(SysInfoJpeg) == 1) ||
	    (systemInfo(SysInfoPng) == 1);// True if we can do PNG or JPEG
	canDoSoundFX = (systemInfo(SysInfoMpeg) == 1) ||
	    (systemInfo(SysInfoWav) == 1);
	canDoMusic = (systemInfo(SysInfoMidi) == 1);
	// Check our version number
	versionNumber = systemInfo(SysInfoVersion);
    }
    // Compare two version numbers (e.g. '2.2.6'), starting with the major
    //  number, then minor, then final. Returns -1 if the first number is
    //  less than the second, 0 if they are equal, or 1 if the first is
    //  greater
    compareVersionNumbers(one, two) {
	local firstStr, secondStr, i, j, firstLoc, secondLoc;

	firstStr = one;
	secondStr = two;
	do {
	    firstLoc = find(firstStr, '.');
	    secondLoc = find(secondStr, '.');
	    if (firstLoc) {
		i = toInteger(substr(firstStr, 1, firstLoc - 1));
		firstStr = substr(firstStr, firstLoc + 1,
				  length(firstStr) - firstLoc);
	    }
	    else i = toInteger(firstStr);
	    if (secondLoc) {
		j = toInteger(substr(secondStr, 1, secondLoc - 1));
		secondStr = substr(secondStr, secondLoc + 1,
				   length(secondStr) - secondLoc);
	    }
	    else j = toInteger(secondStr);
	    if (i < j) return -1;
	    if (i > j) return 1;
	} while (firstLoc && secondLoc);
	if (firstLoc) return 1;   // This handles e.g. '2.5.1' vs '2.5'
	if (secondLoc) return -1; // while this handles '2.5' vs '2.5.1'
	return 0;
    }
;

// Make an ID for this module
ModuleID
    name = 'T3Checks'
    byline = 'by Stephen Granade'
    htmlByline = 'by <a href="mailto:stephen@granades.com">Stephen Granade</a>'
    version = '1.0'
;