HTMLPurifier 4.4.0
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00001 <?php 00002 00007 class HTMLPurifier_UnitConverter 00008 { 00009 00010 const ENGLISH = 1; 00011 const METRIC = 2; 00012 const DIGITAL = 3; 00013 00023 protected static $units = array( 00024 self::ENGLISH => array( 00025 'px' => 3, // This is as per CSS 2.1 and Firefox. Your mileage may vary 00026 'pt' => 4, 00027 'pc' => 48, 00028 'in' => 288, 00029 self::METRIC => array('pt', '0.352777778', 'mm'), 00030 ), 00031 self::METRIC => array( 00032 'mm' => 1, 00033 'cm' => 10, 00034 self::ENGLISH => array('mm', '2.83464567', 'pt'), 00035 ), 00036 ); 00037 00041 protected $outputPrecision; 00042 00046 protected $internalPrecision; 00047 00051 private $bcmath; 00052 00053 public function __construct($output_precision = 4, $internal_precision = 10, $force_no_bcmath = false) { 00054 $this->outputPrecision = $output_precision; 00055 $this->internalPrecision = $internal_precision; 00056 $this->bcmath = !$force_no_bcmath && function_exists('bcmul'); 00057 } 00058 00077 public function convert($length, $to_unit) { 00078 00079 if (!$length->isValid()) return false; 00080 00081 $n = $length->getN(); 00082 $unit = $length->getUnit(); 00083 00084 if ($n === '0' || $unit === false) { 00085 return new HTMLPurifier_Length('0', false); 00086 } 00087 00088 $state = $dest_state = false; 00089 foreach (self::$units as $k => $x) { 00090 if (isset($x[$unit])) $state = $k; 00091 if (isset($x[$to_unit])) $dest_state = $k; 00092 } 00093 if (!$state || !$dest_state) return false; 00094 00095 // Some calculations about the initial precision of the number; 00096 // this will be useful when we need to do final rounding. 00097 $sigfigs = $this->getSigFigs($n); 00098 if ($sigfigs < $this->outputPrecision) $sigfigs = $this->outputPrecision; 00099 00100 // BCMath's internal precision deals only with decimals. Use 00101 // our default if the initial number has no decimals, or increase 00102 // it by how ever many decimals, thus, the number of guard digits 00103 // will always be greater than or equal to internalPrecision. 00104 $log = (int) floor(log(abs($n), 10)); 00105 $cp = ($log < 0) ? $this->internalPrecision - $log : $this->internalPrecision; // internal precision 00106 00107 for ($i = 0; $i < 2; $i++) { 00108 00109 // Determine what unit IN THIS SYSTEM we need to convert to 00110 if ($dest_state === $state) { 00111 // Simple conversion 00112 $dest_unit = $to_unit; 00113 } else { 00114 // Convert to the smallest unit, pending a system shift 00115 $dest_unit = self::$units[$state][$dest_state][0]; 00116 } 00117 00118 // Do the conversion if necessary 00119 if ($dest_unit !== $unit) { 00120 $factor = $this->div(self::$units[$state][$unit], self::$units[$state][$dest_unit], $cp); 00121 $n = $this->mul($n, $factor, $cp); 00122 $unit = $dest_unit; 00123 } 00124 00125 // Output was zero, so bail out early. Shouldn't ever happen. 00126 if ($n === '') { 00127 $n = '0'; 00128 $unit = $to_unit; 00129 break; 00130 } 00131 00132 // It was a simple conversion, so bail out 00133 if ($dest_state === $state) { 00134 break; 00135 } 00136 00137 if ($i !== 0) { 00138 // Conversion failed! Apparently, the system we forwarded 00139 // to didn't have this unit. This should never happen! 00140 return false; 00141 } 00142 00143 // Pre-condition: $i == 0 00144 00145 // Perform conversion to next system of units 00146 $n = $this->mul($n, self::$units[$state][$dest_state][1], $cp); 00147 $unit = self::$units[$state][$dest_state][2]; 00148 $state = $dest_state; 00149 00150 // One more loop around to convert the unit in the new system. 00151 00152 } 00153 00154 // Post-condition: $unit == $to_unit 00155 if ($unit !== $to_unit) return false; 00156 00157 // Useful for debugging: 00158 //echo "<pre>n"; 00159 //echo "$n\nsigfigs = $sigfigs\nnew_log = $new_log\nlog = $log\nrp = $rp\n</pre>\n"; 00160 00161 $n = $this->round($n, $sigfigs); 00162 if (strpos($n, '.') !== false) $n = rtrim($n, '0'); 00163 $n = rtrim($n, '.'); 00164 00165 return new HTMLPurifier_Length($n, $unit); 00166 } 00167 00173 public function getSigFigs($n) { 00174 $n = ltrim($n, '0+-'); 00175 $dp = strpos($n, '.'); // decimal position 00176 if ($dp === false) { 00177 $sigfigs = strlen(rtrim($n, '0')); 00178 } else { 00179 $sigfigs = strlen(ltrim($n, '0.')); // eliminate extra decimal character 00180 if ($dp !== 0) $sigfigs--; 00181 } 00182 return $sigfigs; 00183 } 00184 00188 private function add($s1, $s2, $scale) { 00189 if ($this->bcmath) return bcadd($s1, $s2, $scale); 00190 else return $this->scale($s1 + $s2, $scale); 00191 } 00192 00196 private function mul($s1, $s2, $scale) { 00197 if ($this->bcmath) return bcmul($s1, $s2, $scale); 00198 else return $this->scale($s1 * $s2, $scale); 00199 } 00200 00204 private function div($s1, $s2, $scale) { 00205 if ($this->bcmath) return bcdiv($s1, $s2, $scale); 00206 else return $this->scale($s1 / $s2, $scale); 00207 } 00208 00213 private function round($n, $sigfigs) { 00214 $new_log = (int) floor(log(abs($n), 10)); // Number of digits left of decimal - 1 00215 $rp = $sigfigs - $new_log - 1; // Number of decimal places needed 00216 $neg = $n < 0 ? '-' : ''; // Negative sign 00217 if ($this->bcmath) { 00218 if ($rp >= 0) { 00219 $n = bcadd($n, $neg . '0.' . str_repeat('0', $rp) . '5', $rp + 1); 00220 $n = bcdiv($n, '1', $rp); 00221 } else { 00222 // This algorithm partially depends on the standardized 00223 // form of numbers that comes out of bcmath. 00224 $n = bcadd($n, $neg . '5' . str_repeat('0', $new_log - $sigfigs), 0); 00225 $n = substr($n, 0, $sigfigs + strlen($neg)) . str_repeat('0', $new_log - $sigfigs + 1); 00226 } 00227 return $n; 00228 } else { 00229 return $this->scale(round($n, $sigfigs - $new_log - 1), $rp + 1); 00230 } 00231 } 00232 00236 private function scale($r, $scale) { 00237 if ($scale < 0) { 00238 // The f sprintf type doesn't support negative numbers, so we 00239 // need to cludge things manually. First get the string. 00240 $r = sprintf('%.0f', (float) $r); 00241 // Due to floating point precision loss, $r will more than likely 00242 // look something like 4652999999999.9234. We grab one more digit 00243 // than we need to precise from $r and then use that to round 00244 // appropriately. 00245 $precise = (string) round(substr($r, 0, strlen($r) + $scale), -1); 00246 // Now we return it, truncating the zero that was rounded off. 00247 return substr($precise, 0, -1) . str_repeat('0', -$scale + 1); 00248 } 00249 return sprintf('%.' . $scale . 'f', (float) $r); 00250 } 00251 00252 } 00253 00254 // vim: et sw=4 sts=4