XCF.php

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<?php
class XCFHandler extends BitmapHandler {
    function mustRender( $file ) {
        return true;
    }

    function getThumbType( $ext, $mime, $params = null ) {
        return array( 'png', 'image/png' );
    }

    function getImageSize( $image, $filename ) {
        $header = self::getXCFMetaData( $filename );
        if ( !$header ) {
            return false;
        }

        # Forge a return array containing metadata information just like getimagesize()
        # See PHP documentation at: http://www.php.net/getimagesize
        $metadata = array();
        $metadata[0] = $header['width'];
        $metadata[1] = $header['height'];
        $metadata[2] = null; # IMAGETYPE constant, none exist for XCF.
        $metadata[3] = sprintf(
            'height="%s" width="%s"', $header['height'], $header['width']
        );
        $metadata['mime'] = 'image/x-xcf';
        $metadata['channels'] = null;
        $metadata['bits'] = 8; # Always 8-bits per color

        assert( '7 == count($metadata); ' .
            '# return array must contains 7 elements just like getimagesize() return' );

        return $metadata;
    }

    static function getXCFMetaData( $filename ) {
        # Decode master structure
        $f = fopen( $filename, 'rb' );
        if ( !$f ) {
            return false;
        }
        # The image structure always starts at offset 0 in the XCF file.
        # So we just read it :-)
        $binaryHeader = fread( $f, 26 );
        fclose( $f );

        # Master image structure:
        #
        # byte[9] "gimp xcf "  File type magic
        # byte[4] version      XCF version
        #                        "file" - version 0
        #                        "v001" - version 1
        #                        "v002" - version 2
        # byte    0            Zero-terminator for version tag
        # uint32  width        With of canvas
        # uint32  height       Height of canvas
        # uint32  base_type    Color mode of the image; one of
        #                         0: RGB color
        #                         1: Grayscale
        #                         2: Indexed color
        #        (enum GimpImageBaseType in libgimpbase/gimpbaseenums.h)
        try {
            $header = wfUnpack(
                "A9magic" . # A: space padded
                    "/a5version" . # a: zero padded
                    "/Nwidth" . # \
                    "/Nheight" . # N: unsigned long 32bit big endian
                    "/Nbase_type", # /
                $binaryHeader
            );
        } catch ( MWException $mwe ) {
            return false;
        }

        # Check values
        if ( $header['magic'] !== 'gimp xcf' ) {
            wfDebug( __METHOD__ . " '$filename' has invalid magic signature.\n" );

            return false;
        }
        # TODO: we might want to check for sane values of width and height

        wfDebug( __METHOD__ .
            ": canvas size of '$filename' is {$header['width']} x {$header['height']} px\n" );

        return $header;
    }

    public function getMetadata( $file, $filename ) {
        $header = self::getXCFMetadata( $filename );
        $metadata = array();
        if ( $header ) {
            // Try to be consistent with the names used by PNG files.
            // Unclear from base media type if it has an alpha layer,
            // so just assume that it does since it "potentially" could.
            switch ( $header['base_type'] ) {
            case 0:
                $metadata['colorType'] = 'truecolour-alpha';
                break;
            case 1:
                $metadata['colorType'] = 'greyscale-alpha';
                break;
            case 2:
                $metadata['colorType'] = 'index-coloured';
                break;
            default:
                $metadata['colorType'] = 'unknown';

            }
        } else {
            // Marker to prevent repeated attempted extraction
            $metadata['error'] = true;
        }
        return serialize( $metadata );
    }

    public function isMetadataValid( $file, $metadata ) {
        if ( !$metadata ) {
            // Old metadata when we just put an empty string in there
            return self::METADATA_BAD;
        } else {
            return self::METADATA_GOOD;
        }
    }

    protected function getScalerType( $dstPath, $checkDstPath = true ) {
        return "im";
    }

    public function canRender( $file ) {
        wfSuppressWarnings();
        $xcfMeta = unserialize( $file->getMetadata() );
        wfRestoreWarnings();
        if ( isset( $xcfMeta['colorType'] ) && $xcfMeta['colorType'] === 'index-coloured' ) {
            return false;
        }
        return parent::canRender( $file );
    }
}