Use correct ratio when applying image filters to image alternatives (#…

…1147)

Because of a previous change, the keys of the image alternatives array
is no longer the ratio, but rather the image width. We now make sure to
calculate the ratio correctly and use the appropriate one when applying
the image filters.

system/src/Grav/Common/Page/Media.php

@@ -110,8 +110,9 @@ public function __construct($path)
                     $types['alternative'][$i] = MediumFactory::scaledFromMedium($alternatives[$max]['file'], $max, $i);
                 }
 
-                foreach ($types['alternative'] as $ratio => $altMedium) {
+                foreach ($types['alternative'] as $altMedium) {
                     if ($altMedium['file'] != $medium) {
+                        $ratio = $altMedium['file']->get('width') / $medium->get('width');
                         $medium->addAlternative($ratio, $altMedium['file']);
                     }
                 }

system/src/Grav/Common/Page/Medium/ImageMedium.php

@@ -497,7 +497,7 @@ public function __call($method, $args)
         try {
             call_user_func_array([$this->image, $method], $args);
 
-            foreach ($this->alternatives as $ratio => $medium) {
+            foreach ($this->alternatives as $medium) {
                 if (!$medium->image) {
                     $medium->image();
                 }
@@ -509,7 +509,7 @@ public function __call($method, $args)
                 if (isset(self::$magic_resize_actions[$method])) {
                     foreach (self::$magic_resize_actions[$method] as $param) {
                         if (isset($args_copy[$param])) {
-                            $args_copy[$param] = (int) $args_copy[$param] * $ratio;
+                            $args_copy[$param] *= $medium->get('ratio');
                         }
                     }
                 }