Set DefaultMetadataReader when ext-exif is not present

This fixes the issue where an exif reader is used, but ext-exif
is not loaded.

Closes: #501

DependencyInjection/Compiler/MetadataReaderCompilerPass.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the `liip/LiipImagineBundle` project.
+ *
+ * (c) /~https://github.com/liip/LiipImagineBundle/graphs/contributors
+ *
+ * For the full copyright and license information, please view the LICENSE.md
+ * file that was distributed with this source code.
+ */
+
+namespace Liip\ImagineBundle\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * By default, a metadata reader based on the exif php extension is used.
+ * This compiler pass checks if the extension is loaded an switches to a simpler
+ * implementation if not.
+ */
+class MetadataReaderCompilerPass implements CompilerPassInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function process(ContainerBuilder $container)
+    {
+        if (!extension_loaded('exif')) {
+            $container->setParameter('liip_imagine.meta_data.reader.class', 'Imagine\Image\Metadata\DefaultMetadataReader');
+        }
+    }
+}

LiipImagineBundle.php

@@ -13,6 +13,7 @@
 
 use Liip\ImagineBundle\DependencyInjection\Compiler\FiltersCompilerPass;
 use Liip\ImagineBundle\DependencyInjection\Compiler\LoadersCompilerPass;
+use Liip\ImagineBundle\DependencyInjection\Compiler\MetadataReaderCompilerPass;
 use Liip\ImagineBundle\DependencyInjection\Compiler\PostProcessorsCompilerPass;
 use Liip\ImagineBundle\DependencyInjection\Compiler\ResolversCompilerPass;
 use Liip\ImagineBundle\DependencyInjection\Factory\Loader\FileSystemLoaderFactory;
@@ -38,6 +39,7 @@ public function build(ContainerBuilder $container)
         $container->addCompilerPass(new FiltersCompilerPass());
         $container->addCompilerPass(new PostProcessorsCompilerPass());
         $container->addCompilerPass(new ResolversCompilerPass());
+        $container->addCompilerPass(new MetadataReaderCompilerPass());
 
         /** @var $extension LiipImagineExtension */
         $extension = $container->getExtension('liip_imagine');

composer.json

@@ -49,6 +49,7 @@
     "suggest": {
         "amazonwebservices/aws-sdk-for-php": "Required to use AWS version 1 cache resolver.",
         "aws/aws-sdk-php": "Required to use AWS version 2/3 cache resolver.",
+        "ext-exif": "Required to read metadata from Exif information",
         "league/flysystem": "Required to use FlySystem data loader or cache resolver.",
         "monolog/monolog": "A psr/log compatible logger is required to enable logging.",
         "twig/twig": "Required to use the provided Twig extension. Version 1.12 or greater needed."