import { ScaleLinear } from 'd3-scale';
import { ComputedRef, MaybeRefOrGetter } from '../../node_modules/vue';
/**
 * Maps a numeric value to a CSS color string. This is the shape returned by
 * d3 sequential/threshold scales as well as the function callers can pass
 * directly through the `colorScale` prop.
 */
export type ColorScaleFn = (v?: number) => string;
/**
 * Maps a horizontal canvas pixel offset to the color painted at that column.
 */
export type WidthScaleFn = (x: number) => string;
/**
 * Reactive options driving the scale legend derivation. They mirror the props
 * of the `LegendScale` component, accepted as plain values, refs or getters so
 * the composable stays adaptable to how the caller wires its state.
 */
export interface UseLegendScaleOptions {
    /**
     * Width of the legend (and of its color canvas), in pixels.
     */
    width: MaybeRefOrGetter<number>;
    /**
     * Lower bound of the value domain.
     */
    min: MaybeRefOrGetter<number>;
    /**
     * Upper bound of the value domain.
     */
    max: MaybeRefOrGetter<number>;
    /**
     * Current cursor value, or `null`/`undefined` when no cursor is shown.
     */
    cursorValue: MaybeRefOrGetter<number | null | undefined>;
    /**
     * Either a ready-made color scale function, or the name of one of the
     * supported continuous d3-scale factories (`'scaleLinear'`, `'scaleLog'`,
     * `'scalePow'`, `'scaleRadial'`, `'scaleSqrt'`, `'scaleSequential'`,
     * `'scaleSymlog'`, `'scaleTime'`, `'scaleUtc'`) to build a two-stop scale
     * from. Any other factory name must be passed as a ready-made function
     * instead (e.g. `scaleQuantize(...)`).
     */
    colorScale: MaybeRefOrGetter<ColorScaleFn | string>;
    /**
     * Start color of the built-in two-stop scale (used when `colorScale` is a
     * factory name).
     */
    colorScaleStart: MaybeRefOrGetter<string>;
    /**
     * End color of the built-in two-stop scale (used when `colorScale` is a
     * factory name).
     */
    colorScaleEnd: MaybeRefOrGetter<string>;
}
/**
 * Reactive API returned by {@link useLegendScale}.
 */
export interface UseLegendScale {
    /**
     * Color scale mapping a value of the domain to a CSS color. When the
     * `colorScale` option is a factory name, it is a two-stop scale spanning
     * `[min, max]`; otherwise it is the caller-provided function.
     */
    colorScaleFunction: ComputedRef<ColorScaleFn>;
    /**
     * Maps a canvas pixel column to the value it represents on the `[min, max]`
     * domain.
     */
    widthScale: ComputedRef<ScaleLinear<number, number>>;
    /**
     * Maps a canvas pixel column directly to the color painted there, composing
     * {@link widthScale} with {@link colorScaleFunction}.
     */
    widthScaleColor: ComputedRef<WidthScaleFn>;
    /**
     * Pixel columns to paint, from `0` to `width - 1` inclusive: the canvas is
     * sized to exactly `width`, so those are its only valid columns.
     */
    colorScaleWidthRange: ComputedRef<number[]>;
    /**
     * Whether a cursor value is set (and therefore the cursor should render).
     */
    hasCursor: ComputedRef<boolean>;
    /**
     * Left offset of the cursor as a CSS percentage string (e.g. `'33%'`),
     * falling back to `'0%'` when the value is not a number.
     */
    cursorLeft: ComputedRef<string>;
}
/**
 * Owns the d3 scale and color-domain derivation of the `LegendScale`
 * component: it builds the color scale over the value domain, the linear scale
 * mapping canvas pixels to values (and to colors), and the cursor positioning
 * scale. It holds no DOM state — canvas rendering stays in the component.
 *
 * @param options - Reactive scale options (see {@link UseLegendScaleOptions}).
 * @returns The {@link UseLegendScale} API of derived d3 scales and the cursor
 *   placement helpers.
 * @example
 * // Internal building block of the `LegendScale` component; not exported from
 * // the package root. Inside a `<script setup>` block:
 * import { toRef } from 'vue'
 * import { useLegendScale } from '@/composables/useLegendScale'
 *
 * const props = defineProps<{ min?: number, max?: number }>()
 * const { widthScaleColor, cursorLeft } = useLegendScale({
 *   width: toRef(() => props.width),
 *   min: toRef(() => props.min),
 *   max: toRef(() => props.max),
 *   cursorValue: toRef(() => props.cursorValue),
 *   colorScale: toRef(() => props.colorScale),
 *   colorScaleStart: toRef(() => props.colorScaleStart),
 *   colorScaleEnd: toRef(() => props.colorScaleEnd)
 * })
 */
export declare function useLegendScale(options: UseLegendScaleOptions): UseLegendScale;
export default useLegendScale;