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[mediawiki.git] / includes / media / TransformationalImageHandler.php

<?php
/**
 * Base class for handlers which require transforming images in a
 * similar way as BitmapHandler does.
 *
 * This was split from BitmapHandler on the basis that some extensions
 * might want to work in a similar way to BitmapHandler, but for
 * different formats.
 *
 * 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
 */

/**
 * Handler for images that need to be transformed
 *
 * @since 1.24
 * @ingroup Media
 */
abstract class TransformationalImageHandler extends ImageHandler {
        /**
         * @param File $image
         * @param array $params Transform parameters. Entries with the keys 'width'
         * and 'height' are the respective screen width and height, while the keys
         * 'physicalWidth' and 'physicalHeight' indicate the thumbnail dimensions.
         * @return bool
         */
        function normaliseParams( $image, &$params ) {
                if ( !parent::normaliseParams( $image, $params ) ) {
                        return false;
                }

                # Obtain the source, pre-rotation dimensions
                $srcWidth = $image->getWidth( $params['page'] );
                $srcHeight = $image->getHeight( $params['page'] );

                # Don't make an image bigger than the source
                if ( $params['physicalWidth'] >= $srcWidth ) {
                        $params['physicalWidth'] = $srcWidth;
                        $params['physicalHeight'] = $srcHeight;

                        # Skip scaling limit checks if no scaling is required
                        # due to requested size being bigger than source.
                        if ( !$image->mustRender() ) {
                                return true;
                        }
                }

                return true;
        }

        /**
         * Extracts the width/height if the image will be scaled before rotating
         *
         * This will match the physical size/aspect ratio of the original image
         * prior to application of the rotation -- so for a portrait image that's
         * stored as raw landscape with 90-degress rotation, the resulting size
         * will be wider than it is tall.
         *
         * @param array $params Parameters as returned by normaliseParams
         * @param int $rotation The rotation angle that will be applied
         * @return array ($width, $height) array
         */
        public function extractPreRotationDimensions( $params, $rotation ) {
                if ( $rotation == 90 || $rotation == 270 ) {
                        # We'll resize before rotation, so swap the dimensions again
                        $width = $params['physicalHeight'];
                        $height = $params['physicalWidth'];
                } else {
                        $width = $params['physicalWidth'];
                        $height = $params['physicalHeight'];
                }

                return array( $width, $height );
        }

        /**
         * Create a thumbnail.
         *
         * This sets up various parameters, and then calls a helper method
         * based on $this->getScalerType in order to scale the image.
         *
         * @param File $image
         * @param string $dstPath
         * @param string $dstUrl
         * @param array $params
         * @param int $flags
         * @return MediaTransformError|ThumbnailImage|TransformParameterError
         */
        function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) {
                if ( !$this->normaliseParams( $image, $params ) ) {
                        return new TransformParameterError( $params );
                }

                # Create a parameter array to pass to the scaler
                $scalerParams = array(
                        # The size to which the image will be resized
                        'physicalWidth' => $params['physicalWidth'],
                        'physicalHeight' => $params['physicalHeight'],
                        'physicalDimensions' => "{$params['physicalWidth']}x{$params['physicalHeight']}",
                        # The size of the image on the page
                        'clientWidth' => $params['width'],
                        'clientHeight' => $params['height'],
                        # Comment as will be added to the Exif of the thumbnail
                        'comment' => isset( $params['descriptionUrl'] )
                                ? "File source: {$params['descriptionUrl']}"
                                : '',
                        # Properties of the original image
                        'srcWidth' => $image->getWidth(),
                        'srcHeight' => $image->getHeight(),
                        'mimeType' => $image->getMimeType(),
                        'dstPath' => $dstPath,
                        'dstUrl' => $dstUrl,
                );

                if ( isset( $params['quality'] ) && $params['quality'] === 'low' ) {
                        $scalerParams['quality'] = 30;
                }

                // For subclasses that might be paged.
                if ( $image->isMultipage() && isset( $params['page'] ) ) {
                        $scalerParams['page'] = intval( $params['page'] );
                }

                # Determine scaler type
                $scaler = $this->getScalerType( $dstPath );

                if ( is_array( $scaler ) ) {
                        $scalerName = get_class( $scaler[0] );
                } else {
                        $scalerName = $scaler;
                }

                wfDebug( __METHOD__ . ": creating {$scalerParams['physicalDimensions']} " .
                        "thumbnail at $dstPath using scaler $scalerName\n" );

                if ( !$image->mustRender() &&
                        $scalerParams['physicalWidth'] == $scalerParams['srcWidth']
                        && $scalerParams['physicalHeight'] == $scalerParams['srcHeight']
                        && !isset( $scalerParams['quality'] )
                ) {

                        # normaliseParams (or the user) wants us to return the unscaled image
                        wfDebug( __METHOD__ . ": returning unscaled image\n" );

                        return $this->getClientScalingThumbnailImage( $image, $scalerParams );
                }

                if ( $scaler == 'client' ) {
                        # Client-side image scaling, use the source URL
                        # Using the destination URL in a TRANSFORM_LATER request would be incorrect
                        return $this->getClientScalingThumbnailImage( $image, $scalerParams );
                }

                if ( !$this->isImageAreaOkForThumbnaling( $image, $params ) ) {
                        global $wgMaxImageArea;
                        return new TransformTooBigImageAreaError( $params, $wgMaxImageArea );
                }

                if ( $flags & self::TRANSFORM_LATER ) {
                        wfDebug( __METHOD__ . ": Transforming later per flags.\n" );
                        $newParams = array(
                                'width' => $scalerParams['clientWidth'],
                                'height' => $scalerParams['clientHeight']
                        );
                        if ( isset( $params['quality'] ) ) {
                                $newParams['quality'] = $params['quality'];
                        }
                        if ( isset( $params['page'] ) && $params['page'] ) {
                                $newParams['page'] = $params['page'];
                        }
                        return new ThumbnailImage( $image, $dstUrl, false, $newParams );
                }

                # Try to make a target path for the thumbnail
                if ( !wfMkdirParents( dirname( $dstPath ), null, __METHOD__ ) ) {
                        wfDebug( __METHOD__ . ": Unable to create thumbnail destination " .
                                "directory, falling back to client scaling\n" );

                        return $this->getClientScalingThumbnailImage( $image, $scalerParams );
                }

                # Transform functions and binaries need a FS source file
                $thumbnailSource = $this->getThumbnailSource( $image, $params );

                // If the source isn't the original, disable EXIF rotation because it's already been applied
                if ( $scalerParams['srcWidth'] != $thumbnailSource['width']
                        || $scalerParams['srcHeight'] != $thumbnailSource['height'] ) {
                        $scalerParams['disableRotation'] = true;
                }

                $scalerParams['srcPath'] = $thumbnailSource['path'];
                $scalerParams['srcWidth'] = $thumbnailSource['width'];
                $scalerParams['srcHeight'] = $thumbnailSource['height'];

                if ( $scalerParams['srcPath'] === false ) { // Failed to get local copy
                        wfDebugLog( 'thumbnail',
                                sprintf( 'Thumbnail failed on %s: could not get local copy of "%s"',
                                        wfHostname(), $image->getName() ) );

                        return new MediaTransformError( 'thumbnail_error',
                                $scalerParams['clientWidth'], $scalerParams['clientHeight'],
                                wfMessage( 'filemissing' )->text()
                        );
                }

                # Try a hook. Called "Bitmap" for historical reasons.
                /** @var $mto MediaTransformOutput */
                $mto = null;
                Hooks::run( 'BitmapHandlerTransform', array( $this, $image, &$scalerParams, &$mto ) );
                if ( !is_null( $mto ) ) {
                        wfDebug( __METHOD__ . ": Hook to BitmapHandlerTransform created an mto\n" );
                        $scaler = 'hookaborted';
                }

                // $scaler will return a MediaTransformError on failure, or false on success.
                // If the scaler is succesful, it will have created a thumbnail at the destination
                // path.
                if ( is_array( $scaler ) && is_callable( $scaler ) ) {
                        // Allow subclasses to specify their own rendering methods.
                        $err = call_user_func( $scaler, $image, $scalerParams );
                } else {
                        switch ( $scaler ) {
                                case 'hookaborted':
                                        # Handled by the hook above
                                        $err = $mto->isError() ? $mto : false;
                                        break;
                                case 'im':
                                        $err = $this->transformImageMagick( $image, $scalerParams );
                                        break;
                                case 'custom':
                                        $err = $this->transformCustom( $image, $scalerParams );
                                        break;
                                case 'imext':
                                        $err = $this->transformImageMagickExt( $image, $scalerParams );
                                        break;
                                case 'gd':
                                default:
                                        $err = $this->transformGd( $image, $scalerParams );
                                        break;
                        }
                }

                # Remove the file if a zero-byte thumbnail was created, or if there was an error
                $removed = $this->removeBadFile( $dstPath, (bool)$err );
                if ( $err ) {
                        # transform returned MediaTransforError
                        return $err;
                } elseif ( $removed ) {
                        # Thumbnail was zero-byte and had to be removed
                        return new MediaTransformError( 'thumbnail_error',
                                $scalerParams['clientWidth'], $scalerParams['clientHeight'],
                                wfMessage( 'unknown-error' )->text()
                        );
                } elseif ( $mto ) {
                        return $mto;
                } else {
                        $newParams = array(
                                'width' => $scalerParams['clientWidth'],
                                'height' => $scalerParams['clientHeight']
                        );
                        if ( isset( $params['quality'] ) ) {
                                $newParams['quality'] = $params['quality'];
                        }
                        if ( isset( $params['page'] ) && $params['page'] ) {
                                $newParams['page'] = $params['page'];
                        }
                        return new ThumbnailImage( $image, $dstUrl, $dstPath, $newParams );
                }
        }

        /**
         * Get the source file for the transform
         *
         * @param $file File
         * @param $params Array
         * @return Array Array with keys  width, height and path.
         */
        protected function getThumbnailSource( $file, $params ) {
                return $file->getThumbnailSource( $params );
        }

        /**
         * Returns what sort of scaler type should be used.
         *
         * Values can be one of client, im, custom, gd, imext, or an array
         * of object, method-name to call that specific method.
         *
         * If specifying a custom scaler command with array( Obj, method ),
         * the method in question should take 2 parameters, a File object,
         * and a $scalerParams array with various options (See doTransform
         * for what is in $scalerParams). On error it should return a
         * MediaTransformError object. On success it should return false,
         * and simply make sure the thumbnail file is located at
         * $scalerParams['dstPath'].
         *
         * If there is a problem with the output path, it returns "client"
         * to do client side scaling.
         *
         * @param string $dstPath
         * @param bool $checkDstPath Check that $dstPath is valid
         * @return string|Callable One of client, im, custom, gd, imext, or a Callable array.
         */
        abstract protected function getScalerType( $dstPath, $checkDstPath = true );

        /**
         * Get a ThumbnailImage that respresents an image that will be scaled
         * client side
         *
         * @param File $image File associated with this thumbnail
         * @param array $scalerParams Array with scaler params
         * @return ThumbnailImage
         *
         * @todo FIXME: No rotation support
         */
        protected function getClientScalingThumbnailImage( $image, $scalerParams ) {
                $params = array(
                        'width' => $scalerParams['clientWidth'],
                        'height' => $scalerParams['clientHeight']
                );

                return new ThumbnailImage( $image, $image->getURL(), null, $params );
        }

        /**
         * Transform an image using ImageMagick
         *
         * This is a stub method. The real method is in BitmapHander.
         *
         * @param File $image File associated with this thumbnail
         * @param array $params Array with scaler params
         *
         * @return MediaTransformError Error object if error occurred, false (=no error) otherwise
         */
        protected function transformImageMagick( $image, $params ) {
                return $this->getMediaTransformError( $params, "Unimplemented" );
        }

        /**
         * Transform an image using the Imagick PHP extension
         *
         * This is a stub method. The real method is in BitmapHander.
         *
         * @param File $image File associated with this thumbnail
         * @param array $params Array with scaler params
         *
         * @return MediaTransformError Error object if error occurred, false (=no error) otherwise
         */
        protected function transformImageMagickExt( $image, $params ) {
                return $this->getMediaTransformError( $params, "Unimplemented" );
        }

        /**
         * Transform an image using a custom command
         *
         * This is a stub method. The real method is in BitmapHander.
         *
         * @param File $image File associated with this thumbnail
         * @param array $params Array with scaler params
         *
         * @return MediaTransformError Error object if error occurred, false (=no error) otherwise
         */
        protected function transformCustom( $image, $params ) {
                return $this->getMediaTransformError( $params, "Unimplemented" );
        }

        /**
         * Get a MediaTransformError with error 'thumbnail_error'
         *
         * @param array $params Parameter array as passed to the transform* functions
         * @param string $errMsg Error message
         * @return MediaTransformError
         */
        public function getMediaTransformError( $params, $errMsg ) {
                return new MediaTransformError( 'thumbnail_error', $params['clientWidth'],
                        $params['clientHeight'], $errMsg );
        }

        /**
         * Transform an image using the built in GD library
         *
         * This is a stub method. The real method is in BitmapHander.
         *
         * @param File $image File associated with this thumbnail
         * @param array $params Array with scaler params
         *
         * @return MediaTransformError Error object if error occurred, false (=no error) otherwise
         */
        protected function transformGd( $image, $params ) {
                return $this->getMediaTransformError( $params, "Unimplemented" );
        }

        /**
         * Escape a string for ImageMagick's property input (e.g. -set -comment)
         * See InterpretImageProperties() in magick/property.c
         * @param string $s
         * @return string
         */
        function escapeMagickProperty( $s ) {
                // Double the backslashes
                $s = str_replace( '\\', '\\\\', $s );
                // Double the percents
                $s = str_replace( '%', '%%', $s );
                // Escape initial - or @
                if ( strlen( $s ) > 0 && ( $s[0] === '-' || $s[0] === '@' ) ) {
                        $s = '\\' . $s;
                }

                return $s;
        }

        /**
         * Escape a string for ImageMagick's input filenames. See ExpandFilenames()
         * and GetPathComponent() in magick/utility.c.
         *
         * This won't work with an initial ~ or @, so input files should be prefixed
         * with the directory name.
         *
         * Glob character unescaping is broken in ImageMagick before 6.6.1-5, but
         * it's broken in a way that doesn't involve trying to convert every file
         * in a directory, so we're better off escaping and waiting for the bugfix
         * to filter down to users.
         *
         * @param string $path The file path
         * @param bool|string $scene The scene specification, or false if there is none
         * @throws MWException
         * @return string
         */
        function escapeMagickInput( $path, $scene = false ) {
                # Die on initial metacharacters (caller should prepend path)
                $firstChar = substr( $path, 0, 1 );
                if ( $firstChar === '~' || $firstChar === '@' ) {
                        throw new MWException( __METHOD__ . ': cannot escape this path name' );
                }

                # Escape glob chars
                $path = preg_replace( '/[*?\[\]{}]/', '\\\\\0', $path );

                return $this->escapeMagickPath( $path, $scene );
        }

        /**
         * Escape a string for ImageMagick's output filename. See
         * InterpretImageFilename() in magick/image.c.
         * @param string $path The file path
         * @param bool|string $scene The scene specification, or false if there is none
         * @return string
         */
        function escapeMagickOutput( $path, $scene = false ) {
                $path = str_replace( '%', '%%', $path );

                return $this->escapeMagickPath( $path, $scene );
        }

        /**
         * Armour a string against ImageMagick's GetPathComponent(). This is a
         * helper function for escapeMagickInput() and escapeMagickOutput().
         *
         * @param string $path The file path
         * @param bool|string $scene The scene specification, or false if there is none
         * @throws MWException
         * @return string
         */
        protected function escapeMagickPath( $path, $scene = false ) {
                # Die on format specifiers (other than drive letters). The regex is
                # meant to match all the formats you get from "convert -list format"
                if ( preg_match( '/^([a-zA-Z0-9-]+):/', $path, $m ) ) {
                        if ( wfIsWindows() && is_dir( $m[0] ) ) {
                                // OK, it's a drive letter
                                // ImageMagick has a similar exception, see IsMagickConflict()
                        } else {
                                throw new MWException( __METHOD__ . ': unexpected colon character in path name' );
                        }
                }

                # If there are square brackets, add a do-nothing scene specification
                # to force a literal interpretation
                if ( $scene === false ) {
                        if ( strpos( $path, '[' ) !== false ) {
                                $path .= '[0--1]';
                        }
                } else {
                        $path .= "[$scene]";
                }

                return $path;
        }

        /**
         * Retrieve the version of the installed ImageMagick
         * You can use PHPs version_compare() to use this value
         * Value is cached for one hour.
         * @return string Representing the IM version.
         */
        protected function getMagickVersion() {
                global $wgMemc;

                $cache = $wgMemc->get( "imagemagick-version" );
                if ( !$cache ) {
                        global $wgImageMagickConvertCommand;
                        $cmd = wfEscapeShellArg( $wgImageMagickConvertCommand ) . ' -version';
                        wfDebug( __METHOD__ . ": Running convert -version\n" );
                        $retval = '';
                        $return = wfShellExec( $cmd, $retval );
                        $x = preg_match( '/Version: ImageMagick ([0-9]*\.[0-9]*\.[0-9]*)/', $return, $matches );
                        if ( $x != 1 ) {
                                wfDebug( __METHOD__ . ": ImageMagick version check failed\n" );

                                return null;
                        }
                        $wgMemc->set( "imagemagick-version", $matches[1], 3600 );

                        return $matches[1];
                }

                return $cache;
        }

        /**
         * Returns whether the current scaler supports rotation.
         *
         * @since 1.24 No longer static
         * @return bool
         */
        public function canRotate() {
                return false;
        }

        /**
         * Should we automatically rotate an image based on exif
         *
         * @since 1.24 No longer static
         * @see $wgEnableAutoRotation
         * @return bool Whether auto rotation is enabled
         */
        public function autoRotateEnabled() {
                return false;
        }

        /**
         * Rotate a thumbnail.
         *
         * This is a stub. See BitmapHandler::rotate.
         *
         * @param File $file
         * @param array $params Rotate parameters.
         *   'rotation' clockwise rotation in degrees, allowed are multiples of 90
         * @since 1.24 Is non-static. From 1.21 it was static
         * @return bool
         */
        public function rotate( $file, $params ) {
                return new MediaTransformError( 'thumbnail_error', 0, 0,
                        get_class( $this ) . ' rotation not implemented' );
        }

        /**
         * Returns whether the file needs to be rendered. Returns true if the
         * file requires rotation and we are able to rotate it.
         *
         * @param File $file
         * @return bool
         */
        public function mustRender( $file ) {
                return $this->canRotate() && $this->getRotation( $file ) != 0;
        }

        /**
         * Check if the file is smaller than the maximum image area for thumbnailing.
         *
         * Runs the 'BitmapHandlerCheckImageArea' hook.
         *
         * @param File $file
         * @param array $params
         * @return bool
         * @since 1.25
         */
        public function isImageAreaOkForThumbnaling( $file, &$params ) {
                global $wgMaxImageArea;

                # For historical reasons, hook starts with BitmapHandler
                $checkImageAreaHookResult = null;
                Hooks::run(
                        'BitmapHandlerCheckImageArea',
                        array( $file, &$params, &$checkImageAreaHookResult )
                );

                if ( !is_null( $checkImageAreaHookResult ) ) {
                        // was set by hook, so return that value
                        return (bool)$checkImageAreaHookResult;
                }

                $srcWidth = $file->getWidth( $params['page'] );
                $srcHeight = $file->getHeight( $params['page'] );

                if ( $srcWidth * $srcHeight > $wgMaxImageArea
                        && !( $file->getMimeType() == 'image/jpeg'
                                && $this->getScalerType( false, false ) == 'im' )
                ) {
                        # Only ImageMagick can efficiently downsize jpg images without loading
                        # the entire file in memory
                        return false;
                }
                return true;
        }
}