wp_get_duotone_filter_svg

wp_get_duotone_filter_svg: 这个函数返回用于在图像上产生双色调效果的双色调过滤器的SVG代码。它与wp_get_duotone_filter_id一起使用，以生成SVG过滤器。

返回预设的duotone过滤器SVG字符串。

function wp_get_duotone_filter_svg( $preset ) {
	$filter_id = wp_get_duotone_filter_id( $preset );

	$duotone_values = array(
		'r' => array(),
		'g' => array(),
		'b' => array(),
		'a' => array(),
	);

	if ( ! isset( $preset['colors'] ) || ! is_array( $preset['colors'] ) ) {
		$preset['colors'] = array();
	}

	foreach ( $preset['colors'] as $color_str ) {
		$color = wp_tinycolor_string_to_rgb( $color_str );

		$duotone_values['r'][] = $color['r'] / 255;
		$duotone_values['g'][] = $color['g'] / 255;
		$duotone_values['b'][] = $color['b'] / 255;
		$duotone_values['a'][] = $color['a'];
	}

	ob_start();

	?>

	<svg
		xmlns="http://www.w3.org/2000/svg"
		viewBox="0 0 0 0"
		width="0"
		height="0"
		focusable="false"
		role="none"
		style="visibility: hidden; position: absolute; left: -9999px; overflow: hidden;"
	>
		<defs>
			<filter id="<?php echo esc_attr( $filter_id ); ?>">
				<feColorMatrix
					color-interpolation-filters="sRGB"
					type="matrix"
					values="
						.299 .587 .114 0 0
						.299 .587 .114 0 0
						.299 .587 .114 0 0
						.299 .587 .114 0 0
					"
				/>
				<feComponentTransfer color-interpolation-filters="sRGB" >
					<feFuncR type="table" tableValues="<?php echo esc_attr( implode( ' ', $duotone_values['r'] ) ); ?>" />
					<feFuncG type="table" tableValues="<?php echo esc_attr( implode( ' ', $duotone_values['g'] ) ); ?>" />
					<feFuncB type="table" tableValues="<?php echo esc_attr( implode( ' ', $duotone_values['b'] ) ); ?>" />
					<feFuncA type="table" tableValues="<?php echo esc_attr( implode( ' ', $duotone_values['a'] ) ); ?>" />
				</feComponentTransfer>
				<feComposite in2="SourceGraphic" operator="in" />
			</filter>
		</defs>
	</svg>

	<?php

	$svg = ob_get_clean();

	if ( ! defined( 'SCRIPT_DEBUG' ) || ! SCRIPT_DEBUG ) {
		// Clean up the whitespace.
		$svg = preg_replace( "/[rnt ]+/", ' ', $svg );
		$svg = str_replace( '> <', '><', $svg );
		$svg = trim( $svg );
	}

	return $svg;
}