<form method="POST">
    <h3>Editing: colors.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Colors block support flag.
 *
 * @package WordPress
 * @since 5.6.0
 */

/**
 * Registers the style and colors block attributes for block types that support it.
 *
 * @since 5.6.0
 * @since 6.1.0 Improved $color_support assignment optimization.
 * @access private
 *
 * @param WP_Block_Type $block_type Block Type.
 */
function wp_register_colors_support( $block_type ) {
	$color_support = false;
	if ( $block_type instanceof WP_Block_Type ) {
		$color_support = isset( $block_type-&gt;supports['color'] ) ? $block_type-&gt;supports['color'] : false;
	}
	$has_text_colors_support       = true === $color_support ||
		( isset( $color_support['text'] ) &amp;&amp; $color_support['text'] ) ||
		( is_array( $color_support ) &amp;&amp; ! isset( $color_support['text'] ) );
	$has_background_colors_support = true === $color_support ||
		( isset( $color_support['background'] ) &amp;&amp; $color_support['background'] ) ||
		( is_array( $color_support ) &amp;&amp; ! isset( $color_support['background'] ) );
	$has_gradients_support         = isset( $color_support['gradients'] ) ? $color_support['gradients'] : false;
	$has_link_colors_support       = isset( $color_support['link'] ) ? $color_support['link'] : false;
	$has_button_colors_support     = isset( $color_support['button'] ) ? $color_support['button'] : false;
	$has_heading_colors_support    = isset( $color_support['heading'] ) ? $color_support['heading'] : false;
	$has_color_support             = $has_text_colors_support ||
		$has_background_colors_support ||
		$has_gradients_support ||
		$has_link_colors_support ||
		$has_button_colors_support ||
		$has_heading_colors_support;

	if ( ! $block_type-&gt;attributes ) {
		$block_type-&gt;attributes = array();
	}

	if ( $has_color_support &amp;&amp; ! array_key_exists( 'style', $block_type-&gt;attributes ) ) {
		$block_type-&gt;attributes['style'] = array(
			'type' =&gt; 'object',
		);
	}

	if ( $has_background_colors_support &amp;&amp; ! array_key_exists( 'backgroundColor', $block_type-&gt;attributes ) ) {
		$block_type-&gt;attributes['backgroundColor'] = array(
			'type' =&gt; 'string',
		);
	}

	if ( $has_text_colors_support &amp;&amp; ! array_key_exists( 'textColor', $block_type-&gt;attributes ) ) {
		$block_type-&gt;attributes['textColor'] = array(
			'type' =&gt; 'string',
		);
	}

	if ( $has_gradients_support &amp;&amp; ! array_key_exists( 'gradient', $block_type-&gt;attributes ) ) {
		$block_type-&gt;attributes['gradient'] = array(
			'type' =&gt; 'string',
		);
	}
}


/**
 * Adds CSS classes and inline styles for colors to the incoming attributes array.
 * This will be applied to the block markup in the front-end.
 *
 * @since 5.6.0
 * @since 6.1.0 Implemented the style engine to generate CSS and classnames.
 * @access private
 *
 * @param  WP_Block_Type $block_type       Block type.
 * @param  array         $block_attributes Block attributes.
 *
 * @return array Colors CSS classes and inline styles.
 */
function wp_apply_colors_support( $block_type, $block_attributes ) {
	$color_support = isset( $block_type-&gt;supports['color'] ) ? $block_type-&gt;supports['color'] : false;

	if (
		is_array( $color_support ) &amp;&amp;
		wp_should_skip_block_supports_serialization( $block_type, 'color' )
	) {
		return array();
	}

	$has_text_colors_support       = true === $color_support ||
		( isset( $color_support['text'] ) &amp;&amp; $color_support['text'] ) ||
		( is_array( $color_support ) &amp;&amp; ! isset( $color_support['text'] ) );
	$has_background_colors_support = true === $color_support ||
		( isset( $color_support['background'] ) &amp;&amp; $color_support['background'] ) ||
		( is_array( $color_support ) &amp;&amp; ! isset( $color_support['background'] ) );
	$has_gradients_support         = isset( $color_support['gradients'] ) ? $color_support['gradients'] : false;
	$color_block_styles            = array();

	// Text colors.
	if ( $has_text_colors_support &amp;&amp; ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'text' ) ) {
		$preset_text_color          = array_key_exists( 'textColor', $block_attributes ) ? &quot;var:preset|color|{$block_attributes['textColor']}&quot; : null;
		$custom_text_color          = isset( $block_attributes['style']['color']['text'] ) ? $block_attributes['style']['color']['text'] : null;
		$color_block_styles['text'] = $preset_text_color ? $preset_text_color : $custom_text_color;
	}

	// Background colors.
	if ( $has_background_colors_support &amp;&amp; ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'background' ) ) {
		$preset_background_color          = array_key_exists( 'backgroundColor', $block_attributes ) ? &quot;var:preset|color|{$block_attributes['backgroundColor']}&quot; : null;
		$custom_background_color          = isset( $block_attributes['style']['color']['background'] ) ? $block_attributes['style']['color']['background'] : null;
		$color_block_styles['background'] = $preset_background_color ? $preset_background_color : $custom_background_color;
	}

	// Gradients.
	if ( $has_gradients_support &amp;&amp; ! wp_should_skip_block_supports_serialization( $block_type, 'color', 'gradients' ) ) {
		$preset_gradient_color          = array_key_exists( 'gradient', $block_attributes ) ? &quot;var:preset|gradient|{$block_attributes['gradient']}&quot; : null;
		$custom_gradient_color          = isset( $block_attributes['style']['color']['gradient'] ) ? $block_attributes['style']['color']['gradient'] : null;
		$color_block_styles['gradient'] = $preset_gradient_color ? $preset_gradient_color : $custom_gradient_color;
	}

	$attributes = array();
	$styles     = wp_style_engine_get_styles( array( 'color' =&gt; $color_block_styles ), array( 'convert_vars_to_classnames' =&gt; true ) );

	if ( ! empty( $styles['classnames'] ) ) {
		$attributes['class'] = $styles['classnames'];
	}

	if ( ! empty( $styles['css'] ) ) {
		$attributes['style'] = $styles['css'];
	}

	return $attributes;
}

// Register the block support.
WP_Block_Supports::get_instance()-&gt;register(
	'colors',
	array(
		'register_attribute' =&gt; 'wp_register_colors_support',
		'apply'              =&gt; 'wp_apply_colors_support',
	)
);
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