wikimedia/mediawiki-core

<?php
/**
 * Handler for the Gimp's native file format (XCF)
 *
 * Overview:
 *   https://en.wikipedia.org/wiki/XCF_(file_format)
 * Specification in Gnome repository:
 *   http://svn.gnome.org/viewvc/gimp/trunk/devel-docs/xcf.txt?view=markup
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Media
 */

use MediaWiki\Libs\UnpackFailedException;

/**
 * Handler for the Gimp's native file format; getimagesize() doesn't
 * support these files
 *
 * @ingroup Media
 */
class XCFHandler extends BitmapHandler {
    /**
     * @param File $file
     * @return bool
     */
    public function mustRender( $file ) {
        return true;
    }

    /**
     * Render files as PNG
     *
     * @param string $ext
     * @param string $mime
     * @param array|null $params
     * @return array
     */
    public function getThumbType( $ext, $mime, $params = null ) {
        return [ 'png', 'image/png' ];
    }

    /**
     * Metadata for a given XCF file
     *
     * Will return false if file magic signature is not recognized
     * @author Hexmode
     * @author Hashar
     *
     * @param string $filename Full path to a XCF file
     * @return array|null Metadata Array just like PHP getimagesize()
     */
    private static function getXCFMetaData( $filename ) {
        # Decode master structure
        $f = fopen( $filename, 'rb' );
        if ( !$f ) {
            return null;
        }
        # 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 = StringUtils::unpack(
                "A9magic" . # A: space padded
                    "/a5version" . # a: zero padded
                    "/Nwidth" . # \
                    "/Nheight" . # N: unsigned long 32bit big endian
                    "/Nbase_type", # /
                $binaryHeader
            );
        } catch ( UnpackFailedException $_ ) {
            return null;
        }

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

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

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

        return $header;
    }

    public function getSizeAndMetadata( $state, $filename ) {
        $header = self::getXCFMetaData( $filename );
        $metadata = [];
        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 [
            'width' => $header['width'] ?? 0,
            'height' => $header['height'] ?? 0,
            'bits' => 8,
            'metadata' => $metadata
        ];
    }

    /**
     * Should we refresh the metadata
     *
     * @param File $file The file object for the file in question
     * @return bool|int One of the self::METADATA_(BAD|GOOD|COMPATIBLE) constants
     */
    public function isFileMetadataValid( $file ) {
        if ( !$file->getMetadataArray() ) {
            // Old metadata when we just put an empty string in there
            return self::METADATA_BAD;
        }

        return self::METADATA_GOOD;
    }

    protected function hasGDSupport() {
        return false;
    }

    /**
     * Can we render this file?
     *
     * Image magick doesn't support indexed xcf files as of current
     * writing (as of 6.8.9-3)
     * @param File $file
     * @return bool
     */
    public function canRender( $file ) {
        $xcfMeta = $file->getMetadataArray();
        if ( isset( $xcfMeta['colorType'] ) && $xcfMeta['colorType'] === 'index-coloured' ) {
            return false;
        }
        return parent::canRender( $file );
    }
}