[FEATURE] Allow user to define media types to keep

Classes/Emogrifier.php

@@ -78,6 +78,11 @@ class Emogrifier
      */
     private $unprocessableHtmlTags = array('wbr');
 
+    /**
+     * @var bool[]
+     */
+    private $allowedMediaTypes = array('all' => true, 'screen' => true, 'print' => true);
+
     /**
      * @var array[]
      */
@@ -407,6 +412,32 @@ public function removeUnprocessableHtmlTag($tagName)
         }
     }
 
+    /**
+     * Marks a media query type to keep.
+     *
+     * @param string $mediaName the media type name, e.g., "braille"
+     *
+     * @return void
+     */
+    public function addAllowedMediaType($mediaName)
+    {
+        $this->allowedMediaTypes[$mediaName] = true;
+    }
+
+    /**
+     * Drops a media query type from the allowed list.
+     *
+     * @param string $mediaName the tag name, e.g., "braille"
+     *
+     * @return void
+     */
+    public function removeAllowedMediaType($mediaName)
+    {
+        if (isset($this->allowedMediaTypes[$mediaName])) {
+            unset($this->allowedMediaTypes[$mediaName]);
+        }
+    }
+
      /**
       * This removes styles from your email that contain display:none.
       * We need to look for display:none, but we need to do a case-insensitive search. Since DOMDocument only
@@ -615,8 +646,13 @@ private function splitCssAndMediaQuery($css)
     {
         $media = '';
 
-        $css = preg_replace_callback(
-            '#@media\\s+(?:only\\s)?(?:[\\s{\\(]|screen|all)\\s?[^{]+{.*}\\s*}\\s*#misU',
+        $mediaTypesExpression = '';
+        if (!empty($this->allowedMediaTypes)) {
+            $mediaTypesExpression = '|' . implode('|', array_keys($this->allowedMediaTypes));
+        }
+
+        $cssForAllowedMediaTypes = preg_replace_callback(
+            '#@media\\s+(?:only\\s)?(?:[\\s{\\(]' . $mediaTypesExpression . ')\\s?[^{]+{.*}\\s*}\\s*#misU',
             function ($matches) use (&$media) {
                 $media .= $matches[0];
             },
@@ -640,9 +676,9 @@ function ($matches) use (&$media) {
         );
 
         // clean CSS before output
-        $css = preg_replace($search, $replace, $css);
+        $cleanedCss = preg_replace($search, $replace, $cssForAllowedMediaTypes);
 
-        return array('css' => $css, 'media' => $media);
+        return array('css' => $cleanedCss, 'media' => $media);
     }
 
     /**

README.md

@@ -85,6 +85,11 @@ calling the `emogrify` method:
 * `$emogrifier->disableInvisibleNodeRemoval()` - By default, Emogrifier removes
   elements from the DOM that have the style attribute `display: none;`.  If
   you would like to keep invisible elements in the DOM, use this option.
+* `$emogrifier->addAllowedMediaType(string $mediaName)` - By default, Emogrifier
+  will keep only media types `all`, `screen` and `print`. If you want to keep
+  some others, you can use this method to define them.
+* `$emogrifier->removeAllowedMediaType(string $mediaName)` - You can use this
+  method to remove media types that Emogrifier keeps.
 
 
 ## Installing with Composer

Tests/Unit/EmogrifierTest.php

@@ -899,7 +899,6 @@ public function unneededCssThingsDataProvider()
             'style in "braille" media type rule' => array('@media braille {p {color: #000;}}', '#000'),
             'style in "embossed" media type rule' => array('@media embossed {p {color: #000;}}', '#000'),
             'style in "handheld" media type rule' => array('@media handheld {p {color: #000;}}', '#000'),
-            'style in "print" media type rule' => array('@media print {p {color: #000;}}', '#000'),
             'style in "projection" media type rule' => array('@media projection {p {color: #000;}}', '#000'),
             'style in "speech" media type rule' => array('@media speech {p {color: #000;}}', '#000'),
             'style in "tty" media type rule' => array('@media tty {p {color: #000;}}', '#000'),
@@ -939,6 +938,7 @@ public function mediaRulesDataProvider()
             'style in "only screen" media type rule' => array('@media only screen {p {color: #000;}}'),
             'style in media type rule' => array('@media {p {color: #000;}}'),
             'style in "screen" media type rule' => array('@media screen {p {color: #000;}}'),
+            'style in "print" media type rule' => array('@media print {p {color: #000;}}'),
             'style in "all" media type rule' => array('@media all {p {color: #000;}}'),
         );
     }
@@ -962,6 +962,42 @@ public function emogrifyKeepsMediaRules($css)
           );
     }
 
+    /**
+     * @test
+     */
+    public function removeAllowedMediaTypeRemovesStylesForTheGivenMediaType()
+    {
+        $css = '@media screen { html {} }';
+
+        $html = $this->html5DocumentType . self::LF . '<html></html>';
+        $this->subject->setHtml($html);
+        $this->subject->setCss($css);
+        $this->subject->removeAllowedMediaType('screen');
+
+        self::assertNotContains(
+            $css,
+            $this->subject->emogrify()
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function addAllowedMediaTypeKeepsStylesForTheGivenMediaType()
+    {
+        $css = '@media braille { html {} }';
+
+        $html = $this->html5DocumentType . self::LF . '<html></html>';
+        $this->subject->setHtml($html);
+        $this->subject->setCss($css);
+        $this->subject->addAllowedMediaType('braille');
+
+        self::assertContains(
+            $css,
+            $this->subject->emogrify()
+        );
+    }
+
     /**
      * @test
      */
@@ -1111,7 +1147,6 @@ public function invalidMediaPreserveDataProvider()
             'style in "braille" type rule' => array('@media braille { h1 { color:red; } }'),
             'style in "embossed" type rule' => array('@media embossed { h1 { color:red; } }'),
             'style in "handheld" type rule' => array('@media handheld { h1 { color:red; } }'),
-            'style in "print" type rule' => array('@media print { h1 { color:red; } }'),
             'style in "projection" type rule' => array('@media projection { h1 { color:red; } }'),
             'style in "speech" type rule' => array('@media speech { h1 { color:red; } }'),
             'style in "tty" type rule' => array('@media tty { h1 { color:red; } }'),