描述：
允许许主题支持特定的主题功能。
这个函数必须在主题的 functions.php 文件中 调用，如果想通过 hook 调用，则必须使用 after_setup_theme 这个 hook，因为 init hook 对于一些功能来 ，已经太迟了。
用法：
<?php add_theme_support( $feature, $arguments ); ?>参数：
$feature
(string) (必填) 要 加的主题功 的名称。
目前主题支持的功能列表：
- ‘post-formats’
- ‘post-thumbnails’
- ‘custom-background’
- ‘custom-header’
- ‘automatic-feed-links’
- ‘html5’
- ‘title-tag’
- ‘editor-style’ (主题未直接使用的内部注册)
- ‘widgets’ (主题未直接使用的内部注册)
- ‘menus’ (主题未直接使用的内部注册)
默认值: None
$args
(array) (可选) 可选参数（见下文）。如果未通过，则默认为true。
默认值: true
示例：
//让主题支持‘相册’文章形式
add_theme_support( 'post-formats', array( 'gallery' ) );源文件：
/**
* Allows a theme to register its support of a certain feature
*
* Must be called in the theme's functions.php file to work.
* If attached to a hook, it must be after_setup_theme.
* The init hook may be too late for some features.
*
* @since 2.9.0
*
* @global array $_wp_theme_features
*
* @param string $feature The feature being added.
* @return void|bool False on failure, void otherwise.
*/
function add_theme_support( $feature ) {
global $_wp_theme_features;
if ( func_num_args() == 1 )
$args = true;
else
$args = array_slice( func_get_args(), 1 );
switch ( $feature ) {
case 'post-formats' :
if ( is_array( $args[0] ) ) {
$post_formats = get_post_format_slugs();
unset( $post_formats['standard'] );
$args[0] = array_intersect( $args[0], array_keys( $post_formats ) );
}
break;
case 'html5' :
// You can't just pass 'html5', you need to pass an array of types.
if ( empty( $args[0] ) ) {
// Build an array of types for back-compat.
$args = array( 0 => array( 'comment-list', 'comment-form', 'search-form' ) );
} elseif ( ! is_array( $args[0] ) ) {
_doing_it_wrong( "add_theme_support( 'html5' )", __( 'You need to pass an array of types.' ), '3.6.1' );
return false;
}
// Calling 'html5' again merges, rather than overwrites.
if ( isset( $_wp_theme_features['html5'] ) )
$args[0] = array_merge( $_wp_theme_features['html5'][0], $args[0] );
break;
case 'custom-header-uploads' :
return add_theme_support( 'custom-header', array( 'uploads' => true ) );
case 'custom-header' :
if ( ! is_array( $args ) )
$args = array( 0 => array() );
$defaults = array(
'default-image' => '',
'random-default' => false,
'width' => 0,
'height' => 0,
'flex-height' => false,
'flex-width' => false,
'default-text-color' => '',
'header-text' => true,
'uploads' => true,
'wp-head-callback' => '',
'admin-head-callback' => '',
'admin-preview-callback' => '',
);
$jit = isset( $args[0]['__jit'] );
unset( $args[0]['__jit'] );
// Merge in data from previous add_theme_support() calls.
// The first value registered wins. (A child theme is set up first.)
if ( isset( $_wp_theme_features['custom-header'] ) )
$args[0] = wp_parse_args( $_wp_theme_features['custom-header'][0], $args[0] );
// Load in the defaults at the end, as we need to insure first one wins.
// This will cause all constants to be defined, as each arg will then be set to the default.
if ( $jit )
$args[0] = wp_parse_args( $args[0], $defaults );
// If a constant was defined, use that value. Otherwise, define the constant to ensure
// the constant is always accurate (and is not defined later, overriding our value).
// As stated above, the first value wins.
// Once we get to wp_loaded (just-in-time), define any constants we haven't already.
// Constants are lame. Don't reference them. This is just for backwards compatibility.
if ( defined( 'NO_HEADER_TEXT' ) )
$args[0]['header-text'] = ! NO_HEADER_TEXT;
elseif ( isset( $args[0]['header-text'] ) )
define( 'NO_HEADER_TEXT', empty( $args[0]['header-text'] ) );
if ( defined( 'HEADER_IMAGE_WIDTH' ) )
$args[0]['width'] = (int) HEADER_IMAGE_WIDTH;
elseif ( isset( $args[0]['width'] ) )
define( 'HEADER_IMAGE_WIDTH', (int) $args[0]['width'] );
if ( defined( 'HEADER_IMAGE_HEIGHT' ) )
$args[0]['height'] = (int) HEADER_IMAGE_HEIGHT;
elseif ( isset( $args[0]['height'] ) )
define( 'HEADER_IMAGE_HEIGHT', (int) $args[0]['height'] );
if ( defined( 'HEADER_TEXTCOLOR' ) )
$args[0]['default-text-color'] = HEADER_TEXTCOLOR;
elseif ( isset( $args[0]['default-text-color'] ) )
define( 'HEADER_TEXTCOLOR', $args[0]['default-text-color'] );
if ( defined( 'HEADER_IMAGE' ) )
$args[0]['default-image'] = HEADER_IMAGE;
elseif ( isset( $args[0]['default-image'] ) )
define( 'HEADER_IMAGE', $args[0]['default-image'] );
if ( $jit && ! empty( $args[0]['default-image'] ) )
$args[0]['random-default'] = false;
// If headers are supported, and we still don't have a defined width or height,
// we have implicit flex sizes.
if ( $jit ) {
if ( empty( $args[0]['width'] ) && empty( $args[0]['flex-width'] ) )
$args[0]['flex-width'] = true;
if ( empty( $args[0]['height'] ) && empty( $args[0]['flex-height'] ) )
$args[0]['flex-height'] = true;
}
break;
case 'custom-background' :
if ( ! is_array( $args ) )
$args = array( 0 => array() );
$defaults = array(
'default-image' => '',
'default-repeat' => 'repeat',
'default-position-x' => 'left',
'default-attachment' => 'scroll',
'default-color' => '',
'wp-head-callback' => '_custom_background_cb',
'admin-head-callback' => '',
'admin-preview-callback' => '',
);
$jit = isset( $args[0]['__jit'] );
unset( $args[0]['__jit'] );
// Merge in data from previous add_theme_support() calls. The first value registered wins.
if ( isset( $_wp_theme_features['custom-background'] ) )
$args[0] = wp_parse_args( $_wp_theme_features['custom-background'][0], $args[0] );
if ( $jit )
$args[0] = wp_parse_args( $args[0], $defaults );
if ( defined( 'BACKGROUND_COLOR' ) )
$args[0]['default-color'] = BACKGROUND_COLOR;
elseif ( isset( $args[0]['default-color'] ) || $jit )
define( 'BACKGROUND_COLOR', $args[0]['default-color'] );
if ( defined( 'BACKGROUND_IMAGE' ) )
$args[0]['default-image'] = BACKGROUND_IMAGE;
elseif ( isset( $args[0]['default-image'] ) || $jit )
define( 'BACKGROUND_IMAGE', $args[0]['default-image'] );
break;
// Ensure that 'title-tag' is accessible in the admin.
case 'title-tag' :
// Can be called in functions.php but must happen before wp_loaded, i.e. not in header.php.
if ( did_action( 'wp_loaded' ) ) {
/* translators: 1: Theme support 2: hook name */
_doing_it_wrong( "add_theme_support( 'title-tag' )", sprintf( __( 'Theme support for %1$s should be registered before the %2$s hook.' ),
'title-tag', 'wp_loaded' ), '4.1' );
return false;
}
}
$_wp_theme_features[ $feature ] = $args;
}
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