import { PropertyValues } from 'lit';
import { SlotTextController } from '../../controllers/slot-text-controller/index.js';
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 - Optional heading; when present, must be a single h2–h6 element.
 *   Both constraints (allowed h2–h6 children and a single heading) are validated
 *   in dev mode.
 * @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;
    /**
     * Observes whether the default (illustration) slot has assigned content.
     *
     * @internal
     */
    protected slotText: SlotTextController;
    private readonly _sizePropagation;
    /**
     * Whether the default (illustration) slot has assigned content, so
     * rendering subclasses can collapse the illustration wrapper when no
     * illustration is provided instead of reserving its fixed size.
     */
    protected get hasIllustration(): boolean;
    protected update(changedProperties: PropertyValues): void;
    protected handleActionsSlotChange(): void;
    /**
     * @internal
     *
     * Validates the heading slot: children must be `<h2>`–`<h6>`, and at most a
     * single heading is allowed. Rendering subclasses must wire this to the
     * heading slot's `slotchange` event (e.g.
     * `<slot name="heading" @slotchange=${this.handleHeadingSlotChange}>`) for the
     * validation warnings to fire.
     */
    protected handleHeadingSlotChange(event: Event): void;
}