WordPress标签云小工具是WordPress程序自带的一个小工具，它可以在我们的博客侧边栏展示网站的标签列表。今天WordPress小工具详解系列就从WordPress标签云小工具开始。带大家熟悉标签云小工具的各个细节。

在【外观->小工具】菜单中就可以找到标签云小工具，将它拖到我们的侧边栏中，就可以了。

我们可以设置标签云小工具的标题，你可以取你想要展示的名称【如：热门标签，热门搜索，标签云集等等】。还能设置标签的分类法，WordPress标签小工具可以设置标签分类法和链接分类目录。

设置完成，保存就可以了。

这是WordPress头条的标签云小工具。CSS文件在文章末尾贴给大家。

下面我们来深入分析标签云小工具的源码实现：

标签云源码位置：wp-includes\widgets\class-wp-widget-tag-cloud.php

源代码：(since 4.4.0)

__( 'A cloud of your most used tags.' ),

'customize_selective_refresh' => true,

);

parent::__construct( 'tag_cloud', __( 'Tag Cloud' ), $widget_ops );

}

/**

* Outputs the content for the current Tag Cloud widget instance.

*

* @since 2.8.0

* @access public

*

* @param array $args Display arguments including 'before_title', 'after_title',

* 'before_widget', and 'after_widget'.

* @param array $instance Settings for the current Tag Cloud widget instance.

*/

public function widget( $args, $instance ) {

$current_taxonomy = $this->_get_current_taxonomy($instance);

if ( !empty($instance['title']) ) {

$title = $instance['title'];

} else {

if ( 'post_tag' == $current_taxonomy ) {

$title = __('Tags');

} else {

$tax = get_taxonomy($current_taxonomy);

$title = $tax->labels->name;

}

}

/**

* Filter the taxonomy used in the Tag Cloud widget.

*

* @since 2.8.0

* @since 3.0.0 Added taxonomy drop-down.

*

* @see wp_tag_cloud()

*

* @param array $current_taxonomy The taxonomy to use in the tag cloud. Default 'tags'.

*/

$tag_cloud = wp_tag_cloud( apply_filters( 'widget_tag_cloud_args', array(

'taxonomy' => $current_taxonomy,

'echo' => false

) ) );

if ( empty( $tag_cloud ) ) {

return;

}

/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */

$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

echo $args['before_widget'];

if ( $title ) {

echo $args['before_title'] . $title . $args['after_title'];

}

echo '';

echo $tag_cloud;

echo "\n";

echo $args['after_widget'];

}

/**

* Handles updating settings for the current Tag Cloud widget instance.

*

* @since 2.8.0

* @access public

*

* @param array $new_instance New settings for this instance as input by the user via

* WP_Widget::form().

* @param array $old_instance Old settings for this instance.

* @return array Settings to save or bool false to cancel saving.

*/

public function update( $new_instance, $old_instance ) {

$instance = array();

$instance['title'] = sanitize_text_field( $new_instance['title'] );

$instance['taxonomy'] = stripslashes($new_instance['taxonomy']);

return $instance;

}

/**

* Outputs the Tag Cloud widget settings form.

*

* @since 2.8.0

* @access public

*

* @param array $instance Current settings.

*/

public function form( $instance ) {

$current_taxonomy = $this->_get_current_taxonomy($instance);

$title_id = $this->get_field_id( 'title' );

$instance['title'] = ! empty( $instance['title'] ) ? esc_attr( $instance['title'] ) : '';

echo '' . __( 'Title:' ) . '

';

$taxonomies = get_taxonomies( array( 'show_tagcloud' => true ), 'object' );

$id = $this->get_field_id( 'taxonomy' );

$name = $this->get_field_name( 'taxonomy' );

$input = '';

switch ( count( $taxonomies ) ) {

// No tag cloud supporting taxonomies found, display error message

case 0:

echo '' . __( 'The tag cloud will not be displayed since there are no taxonomies that support the tag cloud widget.' ) . '';

printf( $input, '' );

break;

// Just a single tag cloud supporting taxonomy found, no need to display options

case 1:

$keys = array_keys( $taxonomies );

$taxonomy = reset( $keys );

printf( $input, esc_attr( $taxonomy ) );

break;

// More than one tag cloud supporting taxonomy found, display options

default:

printf(

'%2$s' .

'', $id, __( 'Taxonomy:' ), $name ); foreach ( $taxonomies as $taxonomy => $tax ) { printf( '%s', esc_attr( $taxonomy ), selected( $taxonomy, $current_taxonomy, false ), $tax->labels->name ); } echo '';

}

}

/**

* Retrieves the taxonomy for the current Tag cloud widget instance.

*

* @since 4.4.0

* @access public

*

* @param array $instance Current settings.

* @return string Name of the current taxonomy if set, otherwise 'post_tag'.

*/

public function _get_current_taxonomy($instance) {

if ( !empty($instance['taxonomy']) && taxonomy_exists($instance['taxonomy']) )

return $instance['taxonomy'];

return 'post_tag';

}

}

这里我们主要看一下这几行代码：

$tag_cloud = wp_tag_cloud( apply_filters( 'widget_tag_cloud_args', array(

'taxonomy' => $current_taxonomy,

'echo' => false

) ) );

主要知识点wp_tag_cloud函数和apply_filters函数。我们知道apply_filters是一个函数过滤器。这样我们就可以定制wp_tag_cloud函数的参数了。

具体的修改方法，请查看如何修改WordPress标签云小工具,你还可以根据WordPress标签云小工具的源码开发属于自己的标签云小工具。

附(本网站使用的标签云小工具CSS代码)：

/* tag-cloud widget */

.widget_links {}

.widget_links li:after {}

.widget_links li:before {}

.widget_tag_cloud {}

.widget_tag_cloud a { padding:3px; float: left;

margin: 0 10px 10px 0;

padding: 0 15px;

background: #fff;

color: #5e6b73;

font-size: 14px;

height: 30px;

line-height: 30px;

border: 1px solid #E8ECEF;

border-radius: 16px;

-webkit-border-radius: 16px; }

.widget_tag_cloud a:hover{background: #a0aebc;border-color: #a0aebc;color: #fff;}

.widget_tag_cloud a:after {}

.widget_tag_cloud a:before {}

.tagcloud { padding:15px 0 15px 0; }