import type { RenderWindow } from '../../plugin.types';
import type { SchedulerModule, SchedulerRuntime } from '../scheduler-runtime';
/**
 * Draws everything behind the event bars: slot columns, row separators,
 * non-working shading, the today column and the current-time marker.
 *
 * Split from the bar renderer because the two have completely different change
 * rates. Bars move whenever an event does; the backdrop only changes when the
 * timeline, the slot window or the row window changes — so keeping them apart
 * means a drag repaints bars without touching a single gridline.
 *
 * ## Why the scheduler draws its own row separators
 *
 * The grid already draws a bottom border on every `.pg-row`, but those rows live
 * inside the column panels. With every resource column pinned left, the centre
 * panel is empty, so there is nothing under the timeline to carry a line. Rather
 * than depend on that accident, the backdrop draws its own separators from the
 * same `RenderWindow.rows` the bars are positioned from — which is what
 * guarantees they line up with the left-hand section exactly, at any scroll
 * offset and with any row height.
 */
export declare class SchedulerBackdrop implements SchedulerModule {
    private readonly runtime;
    private readonly layerEl;
    private canvasEl;
    private readonly colPool;
    private readonly liveCols;
    private readonly linePool;
    private readonly liveLines;
    private nowEl;
    /** Last-written values, so an unchanged frame writes nothing. */
    private builtWidth;
    private builtSlotStart;
    private builtSlotEnd;
    private builtBandTop;
    private builtBandHeight;
    private builtRowCount;
    /**
     * Band top as of the last row-line pass.
     *
     * Tracked separately from the column pass: columns run first and update
     * their own `builtBandTop`, so a shared field would always compare equal
     * here and the lines would never move -- they would stay where the first
     * frame put them and drift away from the rows on every scroll.
     */
    private builtLinesBandTop;
    private builtNowPx;
    private readonly weekendDays;
    private readonly holidayDays;
    private readonly shade;
    constructor(runtime: SchedulerRuntime, layerEl: HTMLElement);
    /**
     * Repaints the backdrop for one frame.
     *
     * Everything is guarded on a cached value, so a pure horizontal scroll that
     * does not uncover a new slot, and a vertical scroll that does not change the
     * rendered row band, both write nothing at all.
     */
    render(window: RenderWindow): void;
    destroy(): void;
    private ensureCanvas;
    /** Slot columns, virtualized to the visible window and recycled. */
    private renderColumns;
    /** Marks a column as weekend, holiday or today. */
    private applyColumnTone;
    /**
     * Horizontal separators, one per rendered row.
     *
     * Positioned from the same rows the bars use, so they align with the pinned
     * resource columns by construction rather than by matching a row height
     * setting in two places.
     */
    private renderRowLines;
    /** A 2px rule at the current instant, when it falls inside the timeline. */
    private renderNowMarker;
}
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