import Viewer from '../../viewer/Viewer';
import ViewerEvent from '../../viewer/ViewerEvent';
import DraggableTool from '../DraggableTool';
import { Tool } from '../Tool';
/**
 * ZoomTool
 */
export default class ZoomTool extends DraggableTool implements Tool {
    /**
     * Holds the current zoom step relative to the drag start time
     */
    private currentStep;
    activate(viewer: Viewer): void;
    deactivate(viewer: Viewer): void;
    dragHandler(ev: ViewerEvent): void;
    dragStartHandler(ev: ViewerEvent): void;
    wheelHandler(ev: ViewerEvent): void;
    private zoomStep;
    private translateBy;
    private scaleSection;
}