Issue #864: Change logic for adding 'data-amp-layout'.

Per feedback, this should apply to all contexts,
As long as they allow <img> with a width and height.
Uses Weston's snippet in the filter callback.
@todo: move it to AMP_Theme_Support.

includes/utils/class-amp-wp-utils.php

@@ -69,16 +69,9 @@ protected static function _wp_translate_php_url_constant_to_key( $constant ) {
 	 * @return array $context      Filtered allowed tags and attributes.
 	 */
 	public static function add_layout( $context, $context_type ) {
-		if ( 'post' !== $context_type ) {
-			return $context;
+		if ( ! empty( $context['img']['width'] ) && ! empty( $context['img']['height'] ) ) {
+			$context['img']['data-amp-layout'] = true;
 		}
-		$img            = isset( $context['img'] ) ? $context['img'] : array();
-		$context['img'] = array_merge(
-			$img,
-			array(
-				'data-amp-layout' => true,
-			)
-		);
 		return $context;
 	}
 

tests/test-amp-wp-utils.php

@@ -51,15 +51,28 @@ function test__method( $url, $expected, $component ) {
 	 * @see AMP_WP_Utils::add_layout()
 	 */
 	public function test_add_layout() {
-		$this->assertEquals( array(), AMP_WP_Utils::add_layout( array(), 'explicit' ) );
-		$this->assertEquals(
-			array(
-				'img' => array(
-					'data-amp-layout' => true,
-				),
+		$attribute             = 'data-amp-layout';
+		$image_no_dimensions   = array(
+			'img' => array(
+				$attribute => true,
 			),
-			AMP_WP_Utils::add_layout( array(), 'post' )
 		);
+		$image_with_dimensions = array_merge(
+			$image_no_dimensions,
+			array(
+				'height' => '100',
+				'width'  => '100',
+			)
+		);
+
+		$this->assertEquals( array(), AMP_WP_Utils::add_layout( array(), 'explicit' ) );
+		$this->assertEquals( $image_no_dimensions, AMP_WP_Utils::add_layout( $image_no_dimensions, 'post' ) );
+
+		$context = AMP_WP_Utils::add_layout( $image_with_dimensions, 'post' );
+		$this->assertTrue( $context['img'][ $attribute ] );
+
+		$context = AMP_WP_Utils::add_layout( $image_with_dimensions, 'explicit' );
+		$this->assertTrue( $context['img'][ $attribute ] );
 
 		add_filter( 'wp_kses_allowed_html', 'AMP_WP_Utils::add_layout', 10, 2 );
 		$image = '<img data-amp-layout="fill">';