Add web app manifest display setting in Reading settings page

pwa.php

@@ -275,3 +275,4 @@ function _pwa_deactivate_plugin() {
 $wp_web_app_manifest->init();
 
 require_once PWA_PLUGIN_DIR . '/wp-admin/options-reading-offline-browsing.php';
+require_once PWA_PLUGIN_DIR . '/wp-admin/options-web-app-manifest-display.php';

tests/test-class-wp-web-app-manifest.php

@@ -266,6 +266,14 @@ public function test_get_manifest() {
 		);
 		$this->assertEquals( $expected_manifest, $actual_manifest );
 
+		// Update display.
+		update_option( 'web_app_manifest_display', 'standalone' );
+
+		$actual_manifest              = $this->instance->get_manifest();
+		$expected_manifest['display'] = 'standalone';
+
+		$this->assertEquals( $expected_manifest, $actual_manifest );
+
 		// Check that icon purpose is `any maskable` if site icon is maskable.
 		$actual_manifest = $this->instance->get_manifest();
 		$this->assertEquals( $expected_manifest, $actual_manifest );

wp-admin/options-web-app-manifest-display.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * Web App manifest display field for the reading settings administration panel.
+ *
+ * As part of a core merge, the code in this file would go inside wp-admin/options-reading.php
+ *
+ * @package PWA
+ */
+
+namespace PWA_WP;
+
+/**
+ * Register web app manifest display setting.
+ */
+function register_web_app_manifest_display_setting() {
+	register_setting(
+		'reading',
+		'web_app_manifest_display',
+		array(
+			'type'              => 'string',
+			'sanitize_callback' => 'sanitize_text_field',
+		)
+	);
+}
+add_action( 'init', __NAMESPACE__ . '\register_web_app_manifest_display_setting' );
+
+/**
+ * Register web app manifest display setting field.
+ */
+function add_web_app_manifest_display_setting_field() {
+	add_settings_field(
+		'web_app_manifest_display',
+		__( 'Display', 'pwa' ),
+		__NAMESPACE__ . '\render_web_app_manifest_display_setting_field',
+		'reading'
+	);
+}
+add_action( 'admin_init', __NAMESPACE__ . '\add_web_app_manifest_display_setting_field' );
+
+/**
+ * Render web app manifest display setting field.
+ */
+function render_web_app_manifest_display_setting_field() {
+	// See: <https://developer.mozilla.org/en-US/docs/Web/Manifest/display#values>.
+	$allowed_values = array( 'fullscreen', 'standalone', 'minimal-ui', 'browser' );
+
+	?>
+	<fieldset>
+		<legend class="screen-reader-text"><span><?php esc_html_e( 'Web App manifest display', 'pwa' ); ?> </span></legend>
+
+		<label for="web_app_manifest_display">
+			<?php esc_html_e( 'Web App manifest display', 'pwa' ); ?>
+		</label>
+
+		<select name="web_app_manifest_display" id="web_app_manifest_display">
+			<?php foreach ( $allowed_values as $value ) : ?>
+				<option value="<?php echo esc_attr( $value ); ?>" <?php selected( $value, get_option( 'web_app_manifest_display', 'minimal-ui' ) ); ?>><?php echo esc_html( $value ); ?></option>
+			<?php endforeach; ?>
+		</select>
+
+		<p class="description">
+			<?php
+			echo wp_kses(
+				__( 'This controls how the web app is displayed when launched from the home screen. See <a href="https://developer.mozilla.org/en-US/docs/Web/Manifest/display" rel="noreferrer noopener" target="_blank">MDN documentation</a> for more information.', 'pwa' ),
+				array( 'a' => array_fill_keys( array( 'href', 'rel', 'target' ), true ) )
+			);
+			?>
+		</p>
+	</fieldset>
+	<?php
+}

wp-includes/class-wp-web-app-manifest.php

@@ -203,7 +203,7 @@ public function get_manifest() {
 		$manifest = array(
 			'name'      => html_entity_decode( get_bloginfo( 'name' ), ENT_QUOTES, 'utf-8' ),
 			'start_url' => home_url( '/' ),
-			'display'   => 'minimal-ui',
+			'display'   => get_option( 'web_app_manifest_display', 'minimal-ui' ),
 			'dir'       => is_rtl() ? 'rtl' : 'ltr',
 		);