sforkowany z mirror/friendica
255 wiersze
9.0 KiB
PHP
255 wiersze
9.0 KiB
PHP
![]() |
<?php
|
||
|
|
||
|
/**
|
||
|
* Class for converting between different unit-lengths as specified by
|
||
|
* CSS.
|
||
|
*/
|
||
|
class HTMLPurifier_UnitConverter
|
||
|
{
|
||
|
|
||
|
const ENGLISH = 1;
|
||
|
const METRIC = 2;
|
||
|
const DIGITAL = 3;
|
||
|
|
||
|
/**
|
||
|
* Units information array. Units are grouped into measuring systems
|
||
|
* (English, Metric), and are assigned an integer representing
|
||
|
* the conversion factor between that unit and the smallest unit in
|
||
|
* the system. Numeric indexes are actually magical constants that
|
||
|
* encode conversion data from one system to the next, with a O(n^2)
|
||
|
* constraint on memory (this is generally not a problem, since
|
||
|
* the number of measuring systems is small.)
|
||
|
*/
|
||
|
protected static $units = array(
|
||
|
self::ENGLISH => array(
|
||
|
'px' => 3, // This is as per CSS 2.1 and Firefox. Your mileage may vary
|
||
|
'pt' => 4,
|
||
|
'pc' => 48,
|
||
|
'in' => 288,
|
||
|
self::METRIC => array('pt', '0.352777778', 'mm'),
|
||
|
),
|
||
|
self::METRIC => array(
|
||
|
'mm' => 1,
|
||
|
'cm' => 10,
|
||
|
self::ENGLISH => array('mm', '2.83464567', 'pt'),
|
||
|
),
|
||
|
);
|
||
|
|
||
|
/**
|
||
|
* Minimum bcmath precision for output.
|
||
|
*/
|
||
|
protected $outputPrecision;
|
||
|
|
||
|
/**
|
||
|
* Bcmath precision for internal calculations.
|
||
|
*/
|
||
|
protected $internalPrecision;
|
||
|
|
||
|
/**
|
||
|
* Whether or not BCMath is available
|
||
|
*/
|
||
|
private $bcmath;
|
||
|
|
||
|
public function __construct($output_precision = 4, $internal_precision = 10, $force_no_bcmath = false) {
|
||
|
$this->outputPrecision = $output_precision;
|
||
|
$this->internalPrecision = $internal_precision;
|
||
|
$this->bcmath = !$force_no_bcmath && function_exists('bcmul');
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Converts a length object of one unit into another unit.
|
||
|
* @param HTMLPurifier_Length $length
|
||
|
* Instance of HTMLPurifier_Length to convert. You must validate()
|
||
|
* it before passing it here!
|
||
|
* @param string $to_unit
|
||
|
* Unit to convert to.
|
||
|
* @note
|
||
|
* About precision: This conversion function pays very special
|
||
|
* attention to the incoming precision of values and attempts
|
||
|
* to maintain a number of significant figure. Results are
|
||
|
* fairly accurate up to nine digits. Some caveats:
|
||
|
* - If a number is zero-padded as a result of this significant
|
||
|
* figure tracking, the zeroes will be eliminated.
|
||
|
* - If a number contains less than four sigfigs ($outputPrecision)
|
||
|
* and this causes some decimals to be excluded, those
|
||
|
* decimals will be added on.
|
||
|
*/
|
||
|
public function convert($length, $to_unit) {
|
||
|
|
||
|
if (!$length->isValid()) return false;
|
||
|
|
||
|
$n = $length->getN();
|
||
|
$unit = $length->getUnit();
|
||
|
|
||
|
if ($n === '0' || $unit === false) {
|
||
|
return new HTMLPurifier_Length('0', false);
|
||
|
}
|
||
|
|
||
|
$state = $dest_state = false;
|
||
|
foreach (self::$units as $k => $x) {
|
||
|
if (isset($x[$unit])) $state = $k;
|
||
|
if (isset($x[$to_unit])) $dest_state = $k;
|
||
|
}
|
||
|
if (!$state || !$dest_state) return false;
|
||
|
|
||
|
// Some calculations about the initial precision of the number;
|
||
|
// this will be useful when we need to do final rounding.
|
||
|
$sigfigs = $this->getSigFigs($n);
|
||
|
if ($sigfigs < $this->outputPrecision) $sigfigs = $this->outputPrecision;
|
||
|
|
||
|
// BCMath's internal precision deals only with decimals. Use
|
||
|
// our default if the initial number has no decimals, or increase
|
||
|
// it by how ever many decimals, thus, the number of guard digits
|
||
|
// will always be greater than or equal to internalPrecision.
|
||
|
$log = (int) floor(log(abs($n), 10));
|
||
|
$cp = ($log < 0) ? $this->internalPrecision - $log : $this->internalPrecision; // internal precision
|
||
|
|
||
|
for ($i = 0; $i < 2; $i++) {
|
||
|
|
||
|
// Determine what unit IN THIS SYSTEM we need to convert to
|
||
|
if ($dest_state === $state) {
|
||
|
// Simple conversion
|
||
|
$dest_unit = $to_unit;
|
||
|
} else {
|
||
|
// Convert to the smallest unit, pending a system shift
|
||
|
$dest_unit = self::$units[$state][$dest_state][0];
|
||
|
}
|
||
|
|
||
|
// Do the conversion if necessary
|
||
|
if ($dest_unit !== $unit) {
|
||
|
$factor = $this->div(self::$units[$state][$unit], self::$units[$state][$dest_unit], $cp);
|
||
|
$n = $this->mul($n, $factor, $cp);
|
||
|
$unit = $dest_unit;
|
||
|
}
|
||
|
|
||
|
// Output was zero, so bail out early. Shouldn't ever happen.
|
||
|
if ($n === '') {
|
||
|
$n = '0';
|
||
|
$unit = $to_unit;
|
||
|
break;
|
||
|
}
|
||
|
|
||
|
// It was a simple conversion, so bail out
|
||
|
if ($dest_state === $state) {
|
||
|
break;
|
||
|
}
|
||
|
|
||
|
if ($i !== 0) {
|
||
|
// Conversion failed! Apparently, the system we forwarded
|
||
|
// to didn't have this unit. This should never happen!
|
||
|
return false;
|
||
|
}
|
||
|
|
||
|
// Pre-condition: $i == 0
|
||
|
|
||
|
// Perform conversion to next system of units
|
||
|
$n = $this->mul($n, self::$units[$state][$dest_state][1], $cp);
|
||
|
$unit = self::$units[$state][$dest_state][2];
|
||
|
$state = $dest_state;
|
||
|
|
||
|
// One more loop around to convert the unit in the new system.
|
||
|
|
||
|
}
|
||
|
|
||
|
// Post-condition: $unit == $to_unit
|
||
|
if ($unit !== $to_unit) return false;
|
||
|
|
||
|
// Useful for debugging:
|
||
|
//echo "<pre>n";
|
||
|
//echo "$n\nsigfigs = $sigfigs\nnew_log = $new_log\nlog = $log\nrp = $rp\n</pre>\n";
|
||
|
|
||
|
$n = $this->round($n, $sigfigs);
|
||
|
if (strpos($n, '.') !== false) $n = rtrim($n, '0');
|
||
|
$n = rtrim($n, '.');
|
||
|
|
||
|
return new HTMLPurifier_Length($n, $unit);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Returns the number of significant figures in a string number.
|
||
|
* @param string $n Decimal number
|
||
|
* @return int number of sigfigs
|
||
|
*/
|
||
|
public function getSigFigs($n) {
|
||
|
$n = ltrim($n, '0+-');
|
||
|
$dp = strpos($n, '.'); // decimal position
|
||
|
if ($dp === false) {
|
||
|
$sigfigs = strlen(rtrim($n, '0'));
|
||
|
} else {
|
||
|
$sigfigs = strlen(ltrim($n, '0.')); // eliminate extra decimal character
|
||
|
if ($dp !== 0) $sigfigs--;
|
||
|
}
|
||
|
return $sigfigs;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Adds two numbers, using arbitrary precision when available.
|
||
|
*/
|
||
|
private function add($s1, $s2, $scale) {
|
||
|
if ($this->bcmath) return bcadd($s1, $s2, $scale);
|
||
|
else return $this->scale($s1 + $s2, $scale);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Multiples two numbers, using arbitrary precision when available.
|
||
|
*/
|
||
|
private function mul($s1, $s2, $scale) {
|
||
|
if ($this->bcmath) return bcmul($s1, $s2, $scale);
|
||
|
else return $this->scale($s1 * $s2, $scale);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Divides two numbers, using arbitrary precision when available.
|
||
|
*/
|
||
|
private function div($s1, $s2, $scale) {
|
||
|
if ($this->bcmath) return bcdiv($s1, $s2, $scale);
|
||
|
else return $this->scale($s1 / $s2, $scale);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Rounds a number according to the number of sigfigs it should have,
|
||
|
* using arbitrary precision when available.
|
||
|
*/
|
||
|
private function round($n, $sigfigs) {
|
||
|
$new_log = (int) floor(log(abs($n), 10)); // Number of digits left of decimal - 1
|
||
|
$rp = $sigfigs - $new_log - 1; // Number of decimal places needed
|
||
|
$neg = $n < 0 ? '-' : ''; // Negative sign
|
||
|
if ($this->bcmath) {
|
||
|
if ($rp >= 0) {
|
||
|
$n = bcadd($n, $neg . '0.' . str_repeat('0', $rp) . '5', $rp + 1);
|
||
|
$n = bcdiv($n, '1', $rp);
|
||
|
} else {
|
||
|
// This algorithm partially depends on the standardized
|
||
|
// form of numbers that comes out of bcmath.
|
||
|
$n = bcadd($n, $neg . '5' . str_repeat('0', $new_log - $sigfigs), 0);
|
||
|
$n = substr($n, 0, $sigfigs + strlen($neg)) . str_repeat('0', $new_log - $sigfigs + 1);
|
||
|
}
|
||
|
return $n;
|
||
|
} else {
|
||
|
return $this->scale(round($n, $sigfigs - $new_log - 1), $rp + 1);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Scales a float to $scale digits right of decimal point, like BCMath.
|
||
|
*/
|
||
|
private function scale($r, $scale) {
|
||
|
if ($scale < 0) {
|
||
|
// The f sprintf type doesn't support negative numbers, so we
|
||
|
// need to cludge things manually. First get the string.
|
||
|
$r = sprintf('%.0f', (float) $r);
|
||
|
// Due to floating point precision loss, $r will more than likely
|
||
|
// look something like 4652999999999.9234. We grab one more digit
|
||
|
// than we need to precise from $r and then use that to round
|
||
|
// appropriately.
|
||
|
$precise = (string) round(substr($r, 0, strlen($r) + $scale), -1);
|
||
|
// Now we return it, truncating the zero that was rounded off.
|
||
|
return substr($precise, 0, -1) . str_repeat('0', -$scale + 1);
|
||
|
}
|
||
|
return sprintf('%.' . $scale . 'f', (float) $r);
|
||
|
}
|
||
|
|
||
|
}
|
||
|
|
||
|
// vim: et sw=4 sts=4
|