includes/media/SVGMetadataExtractor.php

   1 <?php
   2 /**
   3  * SVGMetadataExtractor.php
   4  *
   5  * @file
   6  * @ingroup Media
   7  */
   8
   9 class SVGMetadataExtractor {
  10         static function getMetadata( $filename ) {
  11                 $filter = new XmlSizeFilter();
  12                 $xml = new XmlTypeCheck( $filename, array( $filter, 'filter' ) );
  13                 if( $xml->wellFormed ) {
  14                         return array(
  15                                 'width' => $filter->width,
  16                                 'height' => $filter->height
  17                         );
  18                 }
  19         }
  20 }
  21
  22 class XmlSizeFilter {
  23         const DEFAULT_WIDTH = 512;
  24         const DEFAULT_HEIGHT = 512;
  25         var $first = true;
  26         var $width = self::DEFAULT_WIDTH;
  27         var $height = self::DEFAULT_HEIGHT;
  28         function filter( $name, $attribs ) {
  29                 if( $this->first ) {
  30                         $defaultWidth = self::DEFAULT_WIDTH;
  31                         $defaultHeight = self::DEFAULT_HEIGHT;
  32                         $aspect = 1.0;
  33                         $width = null;
  34                         $height = null;
  35
  36                         if( isset( $attribs['viewBox'] ) ) {
  37                                 // min-x min-y width height
  38                                 $viewBox = preg_split( '/\s+/', trim( $attribs['viewBox'] ) );
  39                                 if( count( $viewBox ) == 4 ) {
  40                                         $viewWidth = $this->scaleSVGUnit( $viewBox[2] );
  41                                         $viewHeight = $this->scaleSVGUnit( $viewBox[3] );
  42                                         if( $viewWidth > 0 && $viewHeight > 0 ) {
  43                                                 $aspect = $viewWidth / $viewHeight;
  44                                                 $defaultHeight = $defaultWidth / $aspect;
  45                                         }
  46                                 }
  47                         }
  48                         if( isset( $attribs['width'] ) ) {
  49                                 $width = $this->scaleSVGUnit( $attribs['width'], $defaultWidth );
  50                         }
  51                         if( isset( $attribs['height'] ) ) {
  52                                 $height = $this->scaleSVGUnit( $attribs['height'], $defaultHeight );
  53                         }
  54
  55                         if( !isset( $width ) && !isset( $height ) ) {
  56                                 $width = $defaultWidth;
  57                                 $height = $width / $aspect;
  58                         } elseif( isset( $width ) && !isset( $height ) ) {
  59                                 $height = $width / $aspect;
  60                         } elseif( isset( $height ) && !isset( $width ) ) {
  61                                 $width = $height * $aspect;
  62                         }
  63
  64                         if( $width > 0 && $height > 0 ) {
  65                                 $this->width = intval( round( $width ) );
  66                                 $this->height = intval( round( $height ) );
  67                         }
  68
  69                         $this->first = false;
  70                 }
  71         }
  72
  73         /**
  74          * Return a rounded pixel equivalent for a labeled CSS/SVG length.
  75          * http://www.w3.org/TR/SVG11/coords.html#UnitIdentifiers
  76          *
  77          * @param $length String: CSS/SVG length.
  78          * @param $viewportSize: Float optional scale for percentage units...
  79          * @return float: length in pixels
  80          */
  81         function scaleSVGUnit( $length, $viewportSize=512 ) {
  82                 static $unitLength = array(
  83                         'px' => 1.0,
  84                         'pt' => 1.25,
  85                         'pc' => 15.0,
  86                         'mm' => 3.543307,
  87                         'cm' => 35.43307,
  88                         'in' => 90.0,
  89                         'em' => 16.0, // fake it?
  90                         'ex' => 12.0, // fake it?
  91                         ''   => 1.0, // "User units" pixels by default
  92                         );
  93                 $matches = array();
  94                 if( preg_match( '/^\s*(\d+(?:\.\d+)?)(em|ex|px|pt|pc|cm|mm|in|%|)\s*$/', $length, $matches ) ) {
  95                         $length = floatval( $matches[1] );
  96                         $unit = $matches[2];
  97                         if( $unit == '%' ) {
  98                                 return $length * 0.01 * $viewportSize;
  99                         } else {
 100                                 return $length * $unitLength[$unit];
 101                         }
 102                 } else {
 103                         // Assume pixels
 104                         return floatval( $length );
 105                 }
 106         }
 107 }