--- /dev/null
+<?php
+
+namespace Drupal\config_translation\FormElement;
+
+use Drupal\Core\Language\LanguageInterface;
+
+/**
+ * Defines the textarea element for the configuration translation interface.
+ */
+class Textarea extends FormElementBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getTranslationElement(LanguageInterface $translation_language, $source_config, $translation_config) {
+ // Estimate a comfortable size of the input textarea.
+ $rows_words = ceil(str_word_count($translation_config) / 5);
+ $rows_newlines = substr_count($translation_config, "\n" ) + 1;
+ $rows = max($rows_words, $rows_newlines);
+
+ return [
+ '#type' => 'textarea',
+ '#rows' => $rows,
+ ] + parent::getTranslationElement($translation_language, $source_config, $translation_config);
+ }
+
+}