File xoops_lib\modules\protector\library\HTMLPurifier\UnitConverter.php

1:	<?php
2:
3:	/**
4:	* Class for converting between different unit-lengths as specified by
5:	* CSS.
6:	*/
7:	class HTMLPurifier_UnitConverter
8:	{
9:
10:	const ENGLISH = 1;
11:	const METRIC = 2;
12:	const DIGITAL = 3;
13:
14:	/**
15:	* Units information array. Units are grouped into measuring systems
16:	* (English, Metric), and are assigned an integer representing
17:	* the conversion factor between that unit and the smallest unit in
18:	* the system. Numeric indexes are actually magical constants that
19:	* encode conversion data from one system to the next, with a O(n^2)
20:	* constraint on memory (this is generally not a problem, since
21:	* the number of measuring systems is small.)
22:	*/
23:	protected static $units = array(
24:	self::ENGLISH => array(
25:	'px' => 3, // This is as per CSS 2.1 and Firefox. Your mileage may vary
26:	'pt' => 4,
27:	'pc' => 48,
28:	'in' => 288,
29:	self::METRIC => array('pt', '0.352777778', 'mm'),
30:	),
31:	self::METRIC => array(
32:	'mm' => 1,
33:	'cm' => 10,
34:	self::ENGLISH => array('mm', '2.83464567', 'pt'),
35:	),
36:	);
37:
38:	/**
39:	* Minimum bcmath precision for output.
40:	* @type int
41:	*/
42:	protected $outputPrecision;
43:
44:	/**
45:	* Bcmath precision for internal calculations.
46:	* @type int
47:	*/
48:	protected $internalPrecision;
49:
50:	/**
51:	* Whether or not BCMath is available.
52:	* @type bool
53:	*/
54:	private $bcmath;
55:
56:	public function __construct($output_precision = 4, $internal_precision = 10, $force_no_bcmath = false)
57:	{
58:	$this->outputPrecision = $output_precision;
59:	$this->internalPrecision = $internal_precision;
60:	$this->bcmath = !$force_no_bcmath && function_exists('bcmul');
61:	}
62:
63:	/**
64:	* Converts a length object of one unit into another unit.
65:	* @param HTMLPurifier_Length $length
66:	* Instance of HTMLPurifier_Length to convert. You must validate()
67:	* it before passing it here!
68:	* @param string $to_unit
69:	* Unit to convert to.
70:	* @return HTMLPurifier_Length\|bool
71:	* @note
72:	* About precision: This conversion function pays very special
73:	* attention to the incoming precision of values and attempts
74:	* to maintain a number of significant figure. Results are
75:	* fairly accurate up to nine digits. Some caveats:
76:	* - If a number is zero-padded as a result of this significant
77:	* figure tracking, the zeroes will be eliminated.
78:	* - If a number contains less than four sigfigs ($outputPrecision)
79:	* and this causes some decimals to be excluded, those
80:	* decimals will be added on.
81:	*/
82:	public function convert($length, $to_unit)
83:	{
84:	if (!$length->isValid()) {
85:	return false;
86:	}
87:
88:	$n = $length->getN();
89:	$unit = $length->getUnit();
90:
91:	if ($n === '0' \|\| $unit === false) {
92:	return new HTMLPurifier_Length('0', false);
93:	}
94:
95:	$state = $dest_state = false;
96:	foreach (self::$units as $k => $x) {
97:	if (isset($x[$unit])) {
98:	$state = $k;
99:	}
100:	if (isset($x[$to_unit])) {
101:	$dest_state = $k;
102:	}
103:	}
104:	if (!$state \|\| !$dest_state) {
105:	return false;
106:	}
107:
108:	// Some calculations about the initial precision of the number;
109:	// this will be useful when we need to do final rounding.
110:	$sigfigs = $this->getSigFigs($n);
111:	if ($sigfigs < $this->outputPrecision) {
112:	$sigfigs = $this->outputPrecision;
113:	}
114:
115:	// BCMath's internal precision deals only with decimals. Use
116:	// our default if the initial number has no decimals, or increase
117:	// it by how ever many decimals, thus, the number of guard digits
118:	// will always be greater than or equal to internalPrecision.
119:	$log = (int)floor(log(abs($n), 10));
120:	$cp = ($log < 0) ? $this->internalPrecision - $log : $this->internalPrecision; // internal precision
121:
122:	for ($i = 0; $i < 2; $i++) {
123:
124:	// Determine what unit IN THIS SYSTEM we need to convert to
125:	if ($dest_state === $state) {
126:	// Simple conversion
127:	$dest_unit = $to_unit;
128:	} else {
129:	// Convert to the smallest unit, pending a system shift
130:	$dest_unit = self::$units[$state][$dest_state][0];
131:	}
132:
133:	// Do the conversion if necessary
134:	if ($dest_unit !== $unit) {
135:	$factor = $this->div(self::$units[$state][$unit], self::$units[$state][$dest_unit], $cp);
136:	$n = $this->mul($n, $factor, $cp);
137:	$unit = $dest_unit;
138:	}
139:
140:	// Output was zero, so bail out early. Shouldn't ever happen.
141:	if ($n === '') {
142:	$n = '0';
143:	$unit = $to_unit;
144:	break;
145:	}
146:
147:	// It was a simple conversion, so bail out
148:	if ($dest_state === $state) {
149:	break;
150:	}
151:
152:	if ($i !== 0) {
153:	// Conversion failed! Apparently, the system we forwarded
154:	// to didn't have this unit. This should never happen!
155:	return false;
156:	}
157:
158:	// Pre-condition: $i == 0
159:
160:	// Perform conversion to next system of units
161:	$n = $this->mul($n, self::$units[$state][$dest_state][1], $cp);
162:	$unit = self::$units[$state][$dest_state][2];
163:	$state = $dest_state;
164:
165:	// One more loop around to convert the unit in the new system.
166:
167:	}
168:
169:	// Post-condition: $unit == $to_unit
170:	if ($unit !== $to_unit) {
171:	return false;
172:	}
173:
174:	// Useful for debugging:
175:	//echo "<pre>n";
176:	//echo "$n\nsigfigs = $sigfigs\nnew_log = $new_log\nlog = $log\nrp = $rp\n</pre>\n";
177:
178:	$n = $this->round($n, $sigfigs);
179:	if (strpos($n, '.') !== false) {
180:	$n = rtrim($n, '0');
181:	}
182:	$n = rtrim($n, '.');
183:
184:	return new HTMLPurifier_Length($n, $unit);
185:	}
186:
187:	/**
188:	* Returns the number of significant figures in a string number.
189:	* @param string $n Decimal number
190:	* @return int number of sigfigs
191:	*/
192:	public function getSigFigs($n)
193:	{
194:	$n = ltrim($n, '0+-');
195:	$dp = strpos($n, '.'); // decimal position
196:	if ($dp === false) {
197:	$sigfigs = strlen(rtrim($n, '0'));
198:	} else {
199:	$sigfigs = strlen(ltrim($n, '0.')); // eliminate extra decimal character
200:	if ($dp !== 0) {
201:	$sigfigs--;
202:	}
203:	}
204:	return $sigfigs;
205:	}
206:
207:	/**
208:	* Adds two numbers, using arbitrary precision when available.
209:	* @param string $s1
210:	* @param string $s2
211:	* @param int $scale
212:	* @return string
213:	*/
214:	private function add($s1, $s2, $scale)
215:	{
216:	if ($this->bcmath) {
217:	return bcadd($s1, $s2, $scale);
218:	} else {
219:	return $this->scale((float)$s1 + (float)$s2, $scale);
220:	}
221:	}
222:
223:	/**
224:	* Multiples two numbers, using arbitrary precision when available.
225:	* @param string $s1
226:	* @param string $s2
227:	* @param int $scale
228:	* @return string
229:	*/
230:	private function mul($s1, $s2, $scale)
231:	{
232:	if ($this->bcmath) {
233:	return bcmul($s1, $s2, $scale);
234:	} else {
235:	return $this->scale((float)$s1 * (float)$s2, $scale);
236:	}
237:	}
238:
239:	/**
240:	* Divides two numbers, using arbitrary precision when available.
241:	* @param string $s1
242:	* @param string $s2
243:	* @param int $scale
244:	* @return string
245:	*/
246:	private function div($s1, $s2, $scale)
247:	{
248:	if ($this->bcmath) {
249:	return bcdiv($s1, $s2, $scale);
250:	} else {
251:	return $this->scale((float)$s1 / (float)$s2, $scale);
252:	}
253:	}
254:
255:	/**
256:	* Rounds a number according to the number of sigfigs it should have,
257:	* using arbitrary precision when available.
258:	* @param float $n
259:	* @param int $sigfigs
260:	* @return string
261:	*/
262:	private function round($n, $sigfigs)
263:	{
264:	$new_log = (int)floor(log(abs($n), 10)); // Number of digits left of decimal - 1
265:	$rp = $sigfigs - $new_log - 1; // Number of decimal places needed
266:	$neg = $n < 0 ? '-' : ''; // Negative sign
267:	if ($this->bcmath) {
268:	if ($rp >= 0) {
269:	$n = bcadd($n, $neg . '0.' . str_repeat('0', $rp) . '5', $rp + 1);
270:	$n = bcdiv($n, '1', $rp);
271:	} else {
272:	// This algorithm partially depends on the standardized
273:	// form of numbers that comes out of bcmath.
274:	$n = bcadd($n, $neg . '5' . str_repeat('0', $new_log - $sigfigs), 0);
275:	$n = substr($n, 0, $sigfigs + strlen($neg)) . str_repeat('0', $new_log - $sigfigs + 1);
276:	}
277:	return $n;
278:	} else {
279:	return $this->scale(round($n, $sigfigs - $new_log - 1), $rp + 1);
280:	}
281:	}
282:
283:	/**
284:	* Scales a float to $scale digits right of decimal point, like BCMath.
285:	* @param float $r
286:	* @param int $scale
287:	* @return string
288:	*/
289:	private function scale($r, $scale)
290:	{
291:	if ($scale < 0) {
292:	// The f sprintf type doesn't support negative numbers, so we
293:	// need to cludge things manually. First get the string.
294:	$r = sprintf('%.0f', (float)$r);
295:	// Due to floating point precision loss, $r will more than likely
296:	// look something like 4652999999999.9234. We grab one more digit
297:	// than we need to precise from $r and then use that to round
298:	// appropriately.
299:	$precise = (string)round(substr($r, 0, strlen($r) + $scale), -1);
300:	// Now we return it, truncating the zero that was rounded off.
301:	return substr($precise, 0, -1) . str_repeat('0', -$scale + 1);
302:	}
303:	return sprintf('%.' . $scale . 'f', (float)$r);
304:	}
305:	}
306:
307:	// vim: et sw=4 sts=4
308:

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