Add temporary template thumbnails

lib/AdminPages/Pages/FormEditor.php

@@ -202,6 +202,7 @@ class FormEditor {
         $templatesData[$formType][] = [
           'id' => $templateId,
           'name' => $form->getName(),
+          'thumbnail' => $form->getThumbnailUrl(),
         ];
       }
     }

lib/Form/Templates/FormTemplate.php

@@ -2,6 +2,7 @@
 
 namespace MailPoet\Form\Templates;
 
+use MailPoet\Config\Env;
 use MailPoet\Entities\FormEntity;
 use MailPoet\Util\CdnAssetUrl;
 use MailPoet\Util\Helpers;
@@ -109,6 +110,22 @@ EOL;
     ];
   }
 
+  public function getThumbnailUrl(): string {
+    if (strpos(get_class($this), 'BelowPages')) {
+      return Env::$assetsUrl . '/img/form_template/belowpage@1130.png';
+    }
+    if (strpos(get_class($this), 'Popup')) {
+      return Env::$assetsUrl . '/img/form_template/popup@1130.png';
+    }
+    if (strpos(get_class($this), 'SlideIn')) {
+      return Env::$assetsUrl . '/img/form_template/slidein@1130.png';
+    }
+    if (strpos(get_class($this), 'FixedBar')) {
+      return Env::$assetsUrl . '/img/form_template/fixedbar@1130.png';
+    }
+    return Env::$assetsUrl . '/img/form_template/widget@1130.png';
+  }
+
   public function getStyles(): string {
     return self::DEFAULT_STYLES;
   }