Merge pull request #30 from dnadesign/feature/themed-default-image

Allow to specify a default image per theme

README.md

@@ -103,6 +103,20 @@ class MyPage extends Page {
 By implementing these properties explicitly in your page classes, you can override the default properties
 defined in the OpenGraphPageExtension.
 
+#### Setting open Graph default image
+
+The Open Graph image is a required property and should be supplied a default image.
+You can set the path to the default image in the yml config
+
+```yml
+TractorCow\OpenGraph\Extensions\OpenGraphObjectExtension:
+  default_image: 'app/images/logo.png'
+  theme_name_default_image: 'app/images/theme-logo.png'
+```
+
+Note that you can specify a different image for each theme by prefixing the default_image config name with the theme name (replace everything that is not a letter with an _).
+This is useful if you want to set a different default image on sub sites.
+
 ### Adding new types
 
 If you wish to add a new og:type you will need to:

src/Extensions/OpenGraphObjectExtension.php

@@ -9,6 +9,7 @@
 use SilverStripe\ORM\DataExtension;
 use SilverStripe\ORM\FieldType\DBText;
 use SilverStripe\SiteConfig\SiteConfig;
+use SilverStripe\View\SSViewer;
 use TractorCow\OpenGraph\Constants\OGDeterminers;
 use TractorCow\OpenGraph\Constants\OGTypes;
 use TractorCow\OpenGraph\Interfaces\IOpenGraphObjectBuilder;
@@ -139,6 +140,20 @@ public function getOGSiteName()
 
     public function getOGImage()
     {
+        // If a theme is in use, check if a default image is provided (theme_name_default_image)
+        // This is useful to have a different default image on sub sites
+        if (SSViewer::config()->uninherited('theme_enabled') === true) {
+            $themes = SSViewer::get_themes();
+            if (isset($themes[0])) {
+                $themeName = preg_replace('/[^\w ]+/ ', '_', strtolower($themes[0]));
+                $config = $themeName . '_default_image';
+
+                if ($image = self::config()->{$config}) {
+                    return Director::absoluteURL(ModuleResourceLoader::resourceURL($image));
+                }
+            }
+        }
+
         // Since og:image is a required property, provide a reasonable default
         if ($image = self::config()->default_image) {
             return Director::absoluteURL(ModuleResourceLoader::resourceURL($image));