import { PropertyValues } from 'lit';
import { SpectrumElement } from '../../element/index.js';
import { IllustratedMessageOrientation, IllustratedMessageSize } from './IllustratedMessage.types.js';
/**
 * An illustrated message displays an illustration and a message, typically
 * used in empty states or error pages.
 *
 * @slot - Decorative or informative SVG illustration
 * @slot heading - The heading element, h2–h6
 *   @todo SWC-1943 Add slot constraints once the CEM slot constraints work is complete:
 *   `{required} {allowedChildren: h2, h3, h4, h5, h6} {maxChildren: 1}`
 * @slot description - Supporting description text
 * @slot actions - Optional action controls displayed below the description, typically a button or button group. Receives `size` automatically from the illustrated message.
 */
export declare abstract class IllustratedMessageBase extends SpectrumElement {
    /**
     * @internal
     */
    static readonly VALID_SIZES: readonly IllustratedMessageSize[];
    /**
     * @internal
     */
    static readonly VALID_ORIENTATIONS: readonly IllustratedMessageOrientation[];
    /**
     * The size of the message
     *
     * @default m
     */
    size: IllustratedMessageSize;
    /**
     * The layout orientation
     */
    orientation: IllustratedMessageOrientation;
    private readonly _sizePropagation;
    protected updated(changedProperties: PropertyValues): void;
    protected handleActionsSlotChange(): void;
    /**
     * @internal
     *
     * Validates that the heading slot only contains `<h2>`–`<h6>` elements.
     * Rendering subclasses must wire this to the heading slot's `slotchange`
     * event (e.g. `<slot name="heading" @slotchange=${this.handleHeadingSlotChange}>`)
     * for the validation warning to fire.
     */
    protected handleHeadingSlotChange(event: Event): void;
}