Allow mobile to reduce image quality

http://www.mediawiki.org/wiki/Requests_for_comment/Reducing_image_quality_for_mobile

Per above RFC, this patch implements the core changes required to
specify quality reduction of JPEG via URL. To test, make sure your
setup uses 404-based thumb generation. Vagrant supports it by adding
"multimedia" role:  $ vagrant add-role multimedia && vagrant provision
* Pick any thumbnail jpeg URL that exists on the test wiki, e.g.
  http://.../images/thumb/4/49/Img.jpg/400px-Img.jpg
* check that basic scaling works by altering 400
* add quality parameter qlow- right before px:
  http://.../images/thumb/4/49/Img.jpg/qlow-400px-Img.jpg

Change-Id: I930ea06be6d302ffc8832d12b251422a9f1b3e75

diff --git a/includes/Linker.php b/includes/Linker.php
index cfa0158..9ec7944 100644 (file)
--- a/includes/Linker.php
+++ b/includes/Linker.php
@@ -530,7 +530,7 @@ class Linker {
         *
         * @param array $handlerParams Associative array of media handler parameters, to be passed
         *       to transform(). Typical keys are "width" and "page".
-        * @param string $time Timestamp of the file, set as false for current
+        * @param string|bool $time Timestamp of the file, set as false for current
         * @param string $query Query params for desc url
         * @param int|null $widthOption Used by the parser to remember the user preference thumbnailsize
         * @since 1.20

diff --git a/includes/media/Bitmap.php b/includes/media/Bitmap.php
index 607c4e5..44be178 100644 (file)
--- a/includes/media/Bitmap.php
+++ b/includes/media/Bitmap.php
@@ -138,6 +138,10 @@ class BitmapHandler extends ImageHandler {
                        'dstUrl' => $dstUrl,
                );
 
+               if ( isset( $params['quality'] ) && $params['quality'] === 'low' ) {
+                       $scalerParams['quality'] = 30;
+               }
+
                # Determine scaler type
                $scaler = self::getScalerType( $dstPath );
 
@@ -147,6 +151,7 @@ class BitmapHandler extends ImageHandler {
                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
@@ -163,12 +168,14 @@ class BitmapHandler extends ImageHandler {
 
                if ( $flags & self::TRANSFORM_LATER ) {
                        wfDebug( __METHOD__ . ": Transforming later per flags.\n" );
-                       $params = array(
+                       $newParams = array(
                                'width' => $scalerParams['clientWidth'],
                                'height' => $scalerParams['clientHeight']
                        );
-
-                       return new ThumbnailImage( $image, $dstUrl, false, $params );
+                       if ( isset( $params['quality'] ) ) {
+                               $newParams['quality'] = $params['quality'];
+                       }
+                       return new ThumbnailImage( $image, $dstUrl, false, $newParams );
                }
 
                # Try to make a target path for the thumbnail
@@ -235,12 +242,14 @@ class BitmapHandler extends ImageHandler {
                } elseif ( $mto ) {
                        return $mto;
                } else {
-                       $params = array(
+                       $newParams = array(
                                'width' => $scalerParams['clientWidth'],
                                'height' => $scalerParams['clientHeight']
                        );
-
-                       return new ThumbnailImage( $image, $dstUrl, $dstPath, $params );
+                       if ( isset( $params['quality'] ) ) {
+                               $newParams['quality'] = $params['quality'];
+                       }
+                       return new ThumbnailImage( $image, $dstUrl, $dstPath, $newParams );
                }
        }
 
@@ -314,7 +323,8 @@ class BitmapHandler extends ImageHandler {
                $animation_post = array();
                $decoderHint = array();
                if ( $params['mimeType'] == 'image/jpeg' ) {
-                       $quality = array( '-quality', '80' ); // 80%
+                       $qualityVal = isset( $params['quality'] ) ? (string) $params['quality'] : null;
+                       $quality = array( '-quality', $qualityVal ?: '80' ); // 80%
                        # Sharpening, see bug 6193
                        if ( ( $params['physicalWidth'] + $params['physicalHeight'] )
                                / ( $params['srcWidth'] + $params['srcHeight'] )
@@ -419,7 +429,8 @@ class BitmapHandler extends ImageHandler {
                                        list( $radius, $sigma ) = explode( 'x', $wgSharpenParameter );
                                        $im->sharpenImage( $radius, $sigma );
                                }
-                               $im->setCompressionQuality( 80 );
+                               $qualityVal = isset( $params['quality'] ) ? (string) $params['quality'] : null;
+                               $im->setCompressionQuality( $qualityVal ?: 80 );
                        } elseif ( $params['mimeType'] == 'image/png' ) {
                                $im->setCompressionQuality( 95 );
                        } elseif ( $params['mimeType'] == 'image/gif' ) {
@@ -531,13 +542,14 @@ class BitmapHandler extends ImageHandler {
                # input routine for this.
 
                $typemap = array(
-                       'image/gif' => array( 'imagecreatefromgif', 'palette', 'imagegif' ),
-                       'image/jpeg' => array( 'imagecreatefromjpeg', 'truecolor',
+                       'image/gif' => array( 'imagecreatefromgif', 'palette', false, 'imagegif' ),
+                       'image/jpeg' => array( 'imagecreatefromjpeg', 'truecolor', true,
                                array( __CLASS__, 'imageJpegWrapper' ) ),
-                       'image/png' => array( 'imagecreatefrompng', 'bits', 'imagepng' ),
-                       'image/vnd.wap.wbmp' => array( 'imagecreatefromwbmp', 'palette', 'imagewbmp' ),
-                       'image/xbm' => array( 'imagecreatefromxbm', 'palette', 'imagexbm' ),
+                       'image/png' => array( 'imagecreatefrompng', 'bits', false, 'imagepng' ),
+                       'image/vnd.wap.wbmp' => array( 'imagecreatefromwbmp', 'palette', false, 'imagewbmp' ),
+                       'image/xbm' => array( 'imagecreatefromxbm', 'palette', false, 'imagexbm' ),
                );
+
                if ( !isset( $typemap[$params['mimeType']] ) ) {
                        $err = 'Image type not supported';
                        wfDebug( "$err\n" );
@@ -545,7 +557,7 @@ class BitmapHandler extends ImageHandler {
 
                        return $this->getMediaTransformError( $params, $errMsg );
                }
-               list( $loader, $colorStyle, $saveType ) = $typemap[$params['mimeType']];
+               list( $loader, $colorStyle, $useQuality, $saveType ) = $typemap[$params['mimeType']];
 
                if ( !function_exists( $loader ) ) {
                        $err = "Incomplete GD library configuration: missing function $loader";
@@ -597,7 +609,12 @@ class BitmapHandler extends ImageHandler {
 
                imagesavealpha( $dst_image, true );
 
-               call_user_func( $saveType, $dst_image, $params['dstPath'] );
+               $funcParams = array( $dst_image, $params['dstPath'] );
+               if ( $useQuality && isset( $params['quality'] ) ) {
+                       $funcParams[] = $params['quality'];
+               }
+               call_user_func_array( $saveType, $funcParams );
+
                imagedestroy( $dst_image );
                imagedestroy( $src_image );
 
@@ -730,9 +747,10 @@ class BitmapHandler extends ImageHandler {
                return $cache;
        }
 
-       static function imageJpegWrapper( $dst_image, $thumbPath ) {
+       // FIXME: transformImageMagick() & transformImageMagickExt() uses JPEG quality 80, here it's 95?
+       static function imageJpegWrapper( $dst_image, $thumbPath, $quality = 95 ) {
                imageinterlace( $dst_image );
-               imagejpeg( $dst_image, $thumbPath, 95 );
+               imagejpeg( $dst_image, $thumbPath, $quality );
        }
 
        /**

diff --git a/includes/media/Jpeg.php b/includes/media/Jpeg.php
index 9ed626f..a0f7acb 100644 (file)
--- a/includes/media/Jpeg.php
+++ b/includes/media/Jpeg.php
@@ -31,6 +31,71 @@
  * @ingroup Media
  */
 class JpegHandler extends ExifBitmapHandler {
+
+       function normaliseParams( $image, &$params ) {
+               if ( !parent::normaliseParams( $image, $params ) ) {
+                       return false;
+               }
+               if ( isset( $params['quality'] ) && !self::validateQuality( $params['quality'] ) ) {
+                       return false;
+               }
+               return true;
+       }
+
+       function validateParam( $name, $value ) {
+               if ( $name === 'quality' ) {
+                       return self::validateQuality( $value );
+               } else {
+                       return parent::validateParam( $name, $value );
+               }
+       }
+
+       /** Validate and normalize quality value to be between 1 and 100 (inclusive).
+        * @param int $value quality value, will be converted to integer or 0 if invalid
+        * @return bool true if the value is valid
+        */
+       private static function validateQuality( $value ) {
+               return $value === 'low';
+       }
+
+       function makeParamString( $params ) {
+               // Prepend quality as "qValue-". This has to match parseParamString() below
+               $res = parent::makeParamString( $params );
+               if ( $res && isset( $params['quality'] ) ) {
+                       $res = "q{$params['quality']}-$res";
+               }
+               return $res;
+       }
+
+       function parseParamString( $str ) {
+               // $str contains "qlow-200px" or "200px" strings because thumb.php would strip the filename
+               // first - check if the string begins with "qlow-", and if so, treat it as quality.
+               // Pass the first portion, or the whole string if "qlow-" not found, to the parent
+               // The parsing must match the makeParamString() above
+               $res = false;
+               $m = false;
+               if ( preg_match( '/q([^-]+)-(.*)$/', $str, $m ) ) {
+                       $v = $m[1];
+                       if ( self::validateQuality( $v ) ) {
+                               $res = parent::parseParamString( $m[2] );
+                               if ( $res ) {
+                                       $res['quality'] = $v;
+                               }
+                       }
+               } else {
+                       $res = parent::parseParamString( $str );
+               }
+               return $res;
+       }
+
+       function getScriptParams( $params ) {
+               $res = parent::getScriptParams( $params );
+               if ( isset( $params['quality'] ) ) {
+                       $res['quality'] = $params['quality'];
+               }
+               return $res;
+       }
+
        function getMetadata( $image, $filename ) {
                try {
                        $meta = BitmapMetadataHandler::Jpeg( $filename );