media_upload_form

media_upload_form函数用于显示WordPress媒体上传器中的媒体上传表单: 当点击”添加媒体”按钮并选择”媒体库”标签时，它被调用。开发人员可以使用这个函数来修改媒体上传表格，或者添加他们自己的自定义媒体上传表格。

输出传统的媒体上传表格。

function media_upload_form( $errors = null ) {
	global $type, $tab, $is_IE, $is_opera;

	if ( ! _device_can_upload() ) {
		echo '<p>' . sprintf(
			/* translators: %s: https://apps.wordpress.org/ */
			__( 'The web browser on your device cannot be used to upload files. You may be able to use the <a href="%s">native app for your device</a> instead.' ),
			'https://apps.wordpress.org/'
		) . '</p>';
		return;
	}

	$upload_action_url = admin_url( 'async-upload.php' );
	$post_id           = isset( $_REQUEST['post_id'] ) ? (int) $_REQUEST['post_id'] : 0;
	$_type             = isset( $type ) ? $type : '';
	$_tab              = isset( $tab ) ? $tab : '';

	$max_upload_size = wp_max_upload_size();
	if ( ! $max_upload_size ) {
		$max_upload_size = 0;
	}

	?>
	<div id="media-upload-notice">
	<?php

	if ( isset( $errors['upload_notice'] ) ) {
		echo $errors['upload_notice'];
	}

	?>
	</div>
	<div id="media-upload-error">
	<?php

	if ( isset( $errors['upload_error'] ) && is_wp_error( $errors['upload_error'] ) ) {
		echo $errors['upload_error']->get_error_message();
	}

	?>
	</div>
	<?php

	if ( is_multisite() && ! is_upload_space_available() ) {
		/**
		 * Fires when an upload will exceed the defined upload space quota for a network site.
		 *
		 * @since 3.5.0
		 */
		do_action( 'upload_ui_over_quota' );
		return;
	}

	/**
	 * Fires just before the legacy (pre-3.5.0) upload interface is loaded.
	 *
	 * @since 2.6.0
	 */
	do_action( 'pre-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	$post_params = array(
		'post_id'  => $post_id,
		'_wpnonce' => wp_create_nonce( 'media-form' ),
		'type'     => $_type,
		'tab'      => $_tab,
		'short'    => '1',
	);

	/**
	 * Filters the media upload post parameters.
	 *
	 * @since 3.1.0 As 'swfupload_post_params'
	 * @since 3.3.0
	 *
	 * @param array $post_params An array of media upload parameters used by Plupload.
	 */
	$post_params = apply_filters( 'upload_post_params', $post_params );

	/*
	* Since 4.9 the `runtimes` setting is hardcoded in our version of Plupload to `html5,html4`,
	* and the `flash_swf_url` and `silverlight_xap_url` are not used.
	*/
	$plupload_init = array(
		'browse_button'    => 'plupload-browse-button',
		'container'        => 'plupload-upload-ui',
		'drop_element'     => 'drag-drop-area',
		'file_data_name'   => 'async-upload',
		'url'              => $upload_action_url,
		'filters'          => array( 'max_file_size' => $max_upload_size . 'b' ),
		'multipart_params' => $post_params,
	);

	/*
	 * Currently only iOS Safari supports multiple files uploading,
	 * but iOS 7.x has a bug that prevents uploading of videos when enabled.
	 * See #29602.
	 */
	if (
		wp_is_mobile() &&
		strpos( $_SERVER['HTTP_USER_AGENT'], 'OS 7_' ) !== false &&
		strpos( $_SERVER['HTTP_USER_AGENT'], 'like Mac OS X' ) !== false
	) {
		$plupload_init['multi_selection'] = false;
	}

	// Check if WebP images can be edited.
	if ( ! wp_image_editor_supports( array( 'mime_type' => 'image/webp' ) ) ) {
		$plupload_init['webp_upload_error'] = true;
	}

	/**
	 * Filters the default Plupload settings.
	 *
	 * @since 3.3.0
	 *
	 * @param array $plupload_init An array of default settings used by Plupload.
	 */
	$plupload_init = apply_filters( 'plupload_init', $plupload_init );

	?>
	<script type="text/javascript">
	<?php
	// Verify size is an int. If not return default value.
	$large_size_h = absint( get_option( 'large_size_h' ) );

	if ( ! $large_size_h ) {
		$large_size_h = 1024;
	}

	$large_size_w = absint( get_option( 'large_size_w' ) );

	if ( ! $large_size_w ) {
		$large_size_w = 1024;
	}

	?>
	var resize_height = <?php echo $large_size_h; ?>, resize_width = <?php echo $large_size_w; ?>,
	wpUploaderInit = <?php echo wp_json_encode( $plupload_init ); ?>;
	</script>

	<div id="plupload-upload-ui" class="hide-if-no-js">
	<?php
	/**
	 * Fires before the upload interface loads.
	 *
	 * @since 2.6.0 As 'pre-flash-upload-ui'
	 * @since 3.3.0
	 */
	do_action( 'pre-plupload-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	?>
	<div id="drag-drop-area">
		<div class="drag-drop-inside">
		<p class="drag-drop-info"><?php _e( 'Drop files to upload' ); ?></p>
		<p><?php _ex( 'or', 'Uploader: Drop files here - or - Select Files' ); ?></p>
		<p class="drag-drop-buttons"><input id="plupload-browse-button" type="button" value="<?php esc_attr_e( 'Select Files' ); ?>" class="button" /></p>
		</div>
	</div>
	<?php
	/**
	 * Fires after the upload interface loads.
	 *
	 * @since 2.6.0 As 'post-flash-upload-ui'
	 * @since 3.3.0
	 */
	do_action( 'post-plupload-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
	?>
	</div>

	<div id="html-upload-ui" class="hide-if-js">
	<?php
	/**
	 * Fires before the upload button in the media upload interface.
	 *
	 * @since 2.6.0
	 */
	do_action( 'pre-html-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	?>
	<p id="async-upload-wrap">
		<label class="screen-reader-text" for="async-upload"><?php _e( 'Upload' ); ?></label>
		<input type="file" name="async-upload" id="async-upload" />
		<?php submit_button( __( 'Upload' ), 'primary', 'html-upload', false ); ?>
		<a href="#" onclick="try{top.tb_remove();}catch(e){}; return false;"><?php _e( 'Cancel' ); ?></a>
	</p>
	<div class="clear"></div>
	<?php
	/**
	 * Fires after the upload button in the media upload interface.
	 *
	 * @since 2.6.0
	 */
	do_action( 'post-html-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	?>
	</div>

<p class="max-upload-size">
	<?php
	/* translators: %s: Maximum allowed file size. */
	printf( __( 'Maximum upload file size: %s.' ), esc_html( size_format( $max_upload_size ) ) );
	?>
</p>
	<?php

	/**
	 * Fires on the post upload UI screen.
	 *
	 * Legacy (pre-3.5.0) media workflow hook.
	 *
	 * @since 2.6.0
	 */
	do_action( 'post-upload-ui' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
}