includes/media/XCF.php

   1 <?php
   2 /**
   3  * Handler for the Gimp's native file format (XCF)
   4  *
   5  * Overview:
   6  *   http://en.wikipedia.org/wiki/XCF_(file_format)
   7  * Specification in Gnome repository:
   8  *   http://svn.gnome.org/viewvc/gimp/trunk/devel-docs/xcf.txt?view=markup
   9  *
  10  * @file
  11  * @ingroup Media
  12  */
  13
  14 /**
  15  * Handler for the Gimp's native file format; getimagesize() doesn't
  16  * support these files
  17  *
  18  * @ingroup Media
  19  */
  20 class XCFHandler extends BitmapHandler {
  21
  22         /**
  23          * @param $file
  24          * @return bool
  25          */
  26         function mustRender( $file ) {
  27                 return true;
  28         }
  29
  30         /**
  31          * Render files as PNG
  32          *
  33          * @param $ext
  34          * @param $mime
  35          * @param $params
  36          * @return array
  37          */
  38         function getThumbType( $ext, $mime, $params = null ) {
  39                 return array( 'png', 'image/png' );
  40         }
  41
  42         /**
  43          * Get width and height from the XCF header.
  44          *
  45          * @param $image
  46          * @param $filename
  47          * @return array
  48          */
  49         function getImageSize( $image, $filename ) {
  50                 return self::getXCFMetaData( $filename );
  51         }
  52
  53         /**
  54          * Metadata for a given XCF file
  55          *
  56          * Will return false if file magic signature is not recognized
  57          * @author Hexmode
  58          * @author Hashar
  59          *
  60          * @param $filename String Full path to a XCF file
  61          * @return bool|array metadata array just like PHP getimagesize()
  62          */
  63         static function getXCFMetaData( $filename ) {
  64                 # Decode master structure
  65                 $f = fopen( $filename, 'rb' );
  66                 if( !$f ) {
  67                         return false;
  68                 }
  69                 # The image structure always starts at offset 0 in the XCF file.
  70                 # So we just read it :-)
  71                 $binaryHeader = fread( $f, 26 );
  72                 fclose($f);
  73
  74                 # Master image structure:
  75                 #
  76                 # byte[9] "gimp xcf "  File type magic
  77                 # byte[4] version      XCF version
  78                 #                        "file" - version 0
  79                 #                        "v001" - version 1
  80                 #                        "v002" - version 2
  81                 # byte    0            Zero-terminator for version tag
  82                 # uint32  width        With of canvas
  83                 # uint32  height       Height of canvas
  84                 # uint32  base_type    Color mode of the image; one of
  85                 #                         0: RGB color
  86                 #                         1: Grayscale
  87                 #                         2: Indexed color
  88                 #        (enum GimpImageBaseType in libgimpbase/gimpbaseenums.h)
  89                 try {
  90                         $header = wfUnpack(
  91                                   "A9magic"     # A: space padded
  92                                 . "/a5version"  # a: zero padded
  93                                 . "/Nwidth"     # \
  94                                 . "/Nheight"    # N: unsigned long 32bit big endian
  95                                 . "/Nbase_type" # /
  96                         , $binaryHeader
  97                         );
  98                 } catch( MWException $mwe ) {
  99                         return false;
 100                 }
 101
 102                 # Check values
 103                 if( $header['magic'] !== 'gimp xcf' ) {
 104                         wfDebug( __METHOD__ . " '$filename' has invalid magic signature.\n" );
 105                         return false;
 106                 }
 107                 # TODO: we might want to check for sane values of width and height
 108
 109                 wfDebug( __METHOD__ . ": canvas size of '$filename' is {$header['width']} x {$header['height']} px\n" );
 110
 111                 # Forge a return array containing metadata information just like getimagesize()
 112                 # See PHP documentation at: http://www.php.net/getimagesize
 113                 $metadata = array();
 114                 $metadata[0] = $header['width'];
 115                 $metadata[1] = $header['height'];
 116                 $metadata[2] = null;   # IMAGETYPE constant, none exist for XCF.
 117                 $metadata[3] = sprintf(
 118                         'height="%s" width="%s"', $header['height'], $header['width']
 119                 );
 120                 $metadata['mime'] = 'image/x-xcf';
 121                 $metadata['channels'] = null;
 122                 $metadata['bits'] = 8;  # Always 8-bits per color
 123
 124                 assert( '7 == count($metadata); # return array must contains 7 elements just like getimagesize() return' );
 125
 126                 return $metadata;
 127         }
 128
 129         /**
 130          * Must use "im" for XCF
 131          *
 132          * @return string
 133          */
 134         protected static function getScalerType( $dstPath, $checkDstPath = true ) {
 135                 return "im";
 136         }
 137 }