/**
 * Geometry helpers for framing a finding on the page.
 *
 * `computeFitScale` returns the transform scale that fits a rectangle
 * into the viewport with padding (clamped to the viewer's zoom limits);
 * `unionBbox` collapses a finding's bbox + regions into one bounding
 * rect so a multi-region finding frames as a single group.
 *
 * Pure + side-effect free so the zoom math is unit-testable without a
 * DOM or the react-zoom-pan-pinch runtime.
 *
 * @module
 */
import type { OverlayItem } from "./types";
/** PDF-points bounding box: ``[x0, y0, x1, y1]`` (origin lower-left). */
export type Bbox = readonly [number, number, number, number];
export interface FitScaleOptions {
    /** CSS-px gap kept between the framed rect and each viewport edge. */
    padding?: number;
    /** Lower zoom bound (transform scale, 1 = 100%). */
    minScale?: number;
    /** Upper zoom bound — stops a tiny finding zooming to a blurry crop. */
    maxScale?: number;
}
/**
 * Scale (1 = 100%) that frames a ``rectWidthPx × rectHeightPx``
 * rectangle inside a ``viewportWidthPx × viewportHeightPx`` viewport,
 * leaving ``padding`` px around it, clamped to ``[minScale, maxScale]``.
 *
 * Degenerate inputs (non-positive rect or viewport) fall back to a
 * clamped 1.0 so a caller never divides by zero or applies NaN.
 */
export declare function computeFitScale(rectWidthPx: number, rectHeightPx: number, viewportWidthPx: number, viewportHeightPx: number, options?: FitScaleOptions): number;
/**
 * Smallest bbox covering every rect in ``rects``, or ``null`` when the
 * list is empty. Corners are normalized, so a rect that arrives with
 * swapped ``x0/x1`` or ``y0/y1`` still contributes correctly.
 */
export declare function unionBbox(rects: readonly Bbox[]): Bbox | null;
/**
 * Every locatable rect on a finding: its ``bbox`` (when present)
 * followed by each entry in ``regions``. Empty for page-level /
 * loc-less findings, which the viewer surfaces in the sidebar but
 * never draws or frames.
 */
export declare function collectItemRects(item: OverlayItem): Bbox[];
/** Union of all of a finding's rects, or ``null`` when loc-less. */
export declare function itemFocusBbox(item: OverlayItem): Bbox | null;
/**
 * Element-wise equality on two bboxes (treating ``null`` as a valid
 * value). Used by the substrate's focus effect to dedupe re-framing:
 * if a finding's id stays the same but its bbox/regions change
 * (e.g. live preflight enriches it in place), we still want to
 * re-fit, but rapid re-renders that hand us an equivalent rect
 * shouldn't yank the view back.
 */
export declare function rectsEqual(a: Bbox | null, b: Bbox | null): boolean;
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