import { GLsizei2 } from './tuples';
/**
 * Mixin that incorporates resize event handling. The mixin depends on the global window resize event and forwards any
 * resize event to every existing instance of this class (global tracking).
 */
export declare abstract class Resizable {
    /**
     * Event identifier for resize event (single point of definition).
     */
    private static readonly EVENT_IDENTIFIER;
    /**
     * Array for referencing all instances of resizable.
     */
    private static instances;
    /**
     * Resize event availability (cached value).
     */
    private static eventSupported;
    private static readonly MUTATION_OBSERVER_CONFIG;
    /**
     * Mutation observer for listening on element style changes.
     */
    private _mutationObserver;
    /**
     * This function is called when the window is resized (and the event listener was successfully registered). The
     * event is forwarded to each registered resizable object.
     */
    protected static resize(): void;
    /**
     * Retrieves the native width and height of a given element in device pixel (size on screen in physical pixels). If
     * the element is not found, or either window or its device pixel ratio are not defined, a default vec2 is returned.
     * If the canvas size is not yet computed, i.e., not provided in px unit, undefined will be return.
     * @param element - DOM element to get the width and height in (native) pixel from.
     * @returns - Size of the element in native screen pixels. Undefined when size is not available in 'px'.
     */
    static elementSize(element: HTMLElement): GLsizei2 | undefined;
    /**
     * Every instance of resizable is registered in the global list of resizable instances. The first instance, however,
     * triggers the registration of the global window resize event listener.
     */
    constructor();
    protected _resizeEventListener: () => void;
    protected _mutationEventListener: () => void;
    /**
     * Observe a certain element for style or class mutations. Any mutation invokes the resize event.
     * @param element - element that can be observed for style mutations (style mutation will trigger resize).
     */
    protected observe(element: HTMLElement): void;
    /**
     * Unregister this instance from the global list of resizable instances. On destruction of the last instance, the
     * resize event handle is removed. Please note that destruction needs to be invoked explicitly.
     */
    protected dispose(): void;
    /**
     * This function is invoked when a resize event happened.
     */
    protected abstract onResize(): void;
}