/** * 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. */ function convert($length, $to_unit) { /** * 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.) */ static $units = array(1 => array('px' => 3, 'pt' => 4, 'pc' => 48, 'in' => 288, 2 => array('pt', '0.352777778', 'mm')), 2 => array('mm' => 1, 'cm' => 10, 1 => array('mm', '2.83464567', 'pt'))); if (!$length->isValid()) { return false; } $n = $length->getN(); $unit = $length->getUnit(); if ($n === '0' || $unit === false) { return new HTMLPurifier_Length('0', false); } $state = $dest_state = false; foreach ($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; } // Cleanup $n for PHP 4.3.9 and 4.3.10. See http://bugs.php.net/bug.php?id=30726 if (strncmp($n, '-.', 2) === 0) { $n = '-0.' . substr($n, 2); } // 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 = $units[$state][$dest_state][0]; } // Do the conversion if necessary if ($dest_unit !== $unit) { $factor = $this->div($units[$state][$unit], $units[$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, $units[$state][$dest_state][1], $cp); $unit = $units[$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); }
/** * 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 $to_unit * Unit to convert to. * @return HTMLPurifier_Length|bool * @note * About precision: This conversion function pays very special * attention to the incoming precision of values and attempts * to maintain a number of significant figure. Results are * fairly accurate up to nine digits. Some caveats: * - If a number is zero-padded as a result of this significant * figure tracking, the zeroes will be eliminated. * - If a number contains less than four sigfigs ($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); }
function testConstruct() { $l = new HTMLPurifier_Length('23', 'in'); $this->assertIdentical($l->getN(), '23'); $this->assertIdentical($l->getUnit(), 'in'); }