Restore legacy $ThemeDir support

src/View/ViewableData.php

@@ -3,9 +3,12 @@
 namespace SilverStripe\View;
 
 use Exception;
+use SilverStripe\Core\Config\Config;
 use SilverStripe\Core\Config\Configurable;
 use SilverStripe\Core\Extensible;
 use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\Core\Manifest\ModuleResourceLoader;
+use SilverStripe\Dev\Deprecation;
 use SilverStripe\ORM\ArrayLib;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\FieldType\DBHTMLText;
@@ -586,6 +589,35 @@ class ViewableData implements IteratorAggregate
         return $this;
     }
 
+    /**
+     * Return the directory if the current active theme (relative to the site root).
+     *
+     * This method is useful for things such as accessing theme images from your template without hardcoding the theme
+     * page - e.g. <img src="$ThemeDir/images/something.gif">.
+     *
+     * This method should only be used when a theme is currently active. However, it will fall over to the current
+     * project directory.
+     *
+     * @return string URL to the current theme
+     * @deprecated 4.0.0..5.0.0 Use $resourcePath or $resourceURL template helpers instead
+     */
+    public function ThemeDir()
+    {
+        Deprecation::notice('5.0', 'Use $resourcePath or $resourceURL template helpers instead');
+        $themes = SSViewer::get_themes();
+        foreach ($themes as $theme) {
+            // Skip theme sets
+            if (strpos($theme, '$') === 0) {
+                continue;
+            }
+            // Map theme path to url
+            $themePath = ThemeResourceLoader::inst()->getPath($theme);
+            return ModuleResourceLoader::resourceURL($themePath);
+        }
+
+        return project();
+    }
+
     /**
      * Get part of the current classes ancestry to be used as a CSS class.
      *

tests/php/View/ViewableDataTest.php

@@ -5,6 +5,7 @@ namespace SilverStripe\View\Tests;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\Dev\SapphireTest;
 use SilverStripe\View\ArrayData;
+use SilverStripe\View\SSViewer;
 use SilverStripe\View\ViewableData;
 
 /**
@@ -204,4 +205,19 @@ class ViewableDataTest extends SapphireTest
         $this->assertSame($failover, $container->getFailover(), 'getFailover() returned a different object');
         $this->assertFalse($container->hasMethod('testMethod'), 'testMethod() incorrectly reported as existing');
     }
+
+    public function testThemeDir()
+    {
+        $themes = [
+            "silverstripe/framework:/tests/php/View/ViewableDataTest/testtheme",
+            SSViewer::DEFAULT_THEME
+        ];
+        SSViewer::set_themes($themes);
+
+        $data = new ViewableData();
+        $this->assertContains(
+            'tests/php/View/ViewableDataTest/testtheme',
+            $data->ThemeDir()
+        );
+    }
 }