Added a new h4 element

src/Facebook/InstantArticles/Elements/H4.php

@@ -0,0 +1,131 @@
+<?php
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+namespace Facebook\InstantArticles\Elements;
+
+use Facebook\InstantArticles\Validators\Type;
+
+/**
+ * Title for the Document
+ *
+ * Example:
+ * <h4> This is the h4 element Instant Article</h4>
+ *  or
+ * <h4> This is a <b> h4 element </b> in the  Instant Article</h4>
+ */
+class H4 extends TextContainer
+{
+    /**
+     * @var string text align. Values: "op-left"|"op-center"|"op-right"
+     */
+    private $textAlignment;
+
+    /**
+     * @var string text position. Values: "op-vertical-below"|"op-vertical-above"|"op-vertical-center"
+     */
+    private $position;
+
+    private function __construct()
+    {
+    }
+
+    public static function create()
+    {
+        return new self();
+    }
+
+
+    /**
+     * The Text alignment that will be used.
+     *
+     * @see Caption::ALIGN_RIGHT
+     * @see Caption::ALIGN_LEFT
+     * @see Caption::ALIGN_CENTER
+     *
+     * @param string $text_alignment option that will be used.
+     */
+    public function withTextAlignment($text_alignment)
+    {
+        Type::enforceWithin(
+            $text_alignment,
+            [
+                Caption::ALIGN_RIGHT,
+                Caption::ALIGN_LEFT,
+                Caption::ALIGN_CENTER
+            ]
+        );
+        $this->textAlignment = $text_alignment;
+
+        return $this;
+    }
+
+    /**
+     * @deprecated
+     *
+     * @param string $position
+     * @return $this
+     */
+    public function withPostion($position)
+    {
+        return $this->withPosition($position);
+    }
+
+    /**
+     * The Text position that will be used.
+     *
+     * @see Caption::POSITION_ABOVE
+     * @see Caption::POSITION_BELOW
+     * @see Caption::POSITION_CENTER
+     *
+     * @param string $position
+     * @return $this
+     */
+    public function withPosition($position)
+    {
+        Type::enforceWithin(
+            $position,
+            [
+                Caption::POSITION_ABOVE,
+                Caption::POSITION_BELOW,
+                Caption::POSITION_CENTER
+            ]
+        );
+        $this->position = $position;
+
+        return $this;
+    }
+
+    /**
+     * Structure and create the H4 in a DOMElement.
+     *
+     * @param \DOMDocument $document - The document where this element will be appended (optional).
+     */
+    public function toDOMElement($document = null)
+    {
+        if (!$document) {
+            $document = new \DOMDocument();
+        }
+
+        $h4 = $document->createElement('h4');
+
+        $classes = [];
+        if ($this->position) {
+            $classes[] = $this->position;
+        }
+        if ($this->textAlignment) {
+            $classes[] = $this->textAlignment;
+        }
+        if (!empty($classes)) {
+            $h4->setAttribute('class', implode(' ', $classes));
+        }
+
+        $h4->appendChild($this->textToDOMDocumentFragment($document));
+
+        return $h4;
+    }
+}