66 lines
No EOL
2.6 KiB
JavaScript
66 lines
No EOL
2.6 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.graphicalItemIdentity = graphicalItemIdentity;
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/**
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* @fileOverview
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* This file provides helper methods for assigning theme identity to a
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* graphical item. Graphical items are individual drawable data representations,
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* such as Line or Bar. In previous Recharts versions these can be styled
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* individually. In next version, Recharts will allow the user to provide an
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* array of themes, and then have the graphical items pick one. There is a gap
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* however; graphical items are not sorted and not indexed. We can't use DOM
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* order because that order changes. So instead we need an identifier that:
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* - we can calculate from props, without requiring the user to provide an
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* explicit id
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* - is stable across renders, so that the same item will always get the same
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* theme
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* - is (within possibilities) unique across all items, so that no two items
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* will get the same theme The uniqueness is impossible to guarantee 100% so
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* we will only provide a best-effort. This file provides a helper method to
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* calculate such an identifier.
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*/
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/**
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* Computes a deterministic numeric hash for the given string. Uses djb2 hash
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* algorithm with additional bit-mixing to improve distribution across small
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* moduli (e.g., themeCount = 5).
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*/
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function computeHash(str) {
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var hash = 5381;
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for (var i = 0; i < str.length; i++) {
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hash = (hash << 5) + hash + str.charCodeAt(i); // hash * 33 + charCode
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}
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// Bit-mixing step: multiply by a large prime, then XOR-shift to spread
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// bit patterns. This prevents collisions that can occur with raw %
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// themeCount when the raw hash's low bits correlate poorly across inputs.
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hash ^= hash >>> 16;
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hash *= 0x85ebca6b;
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hash ^= hash >>> 16;
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return hash & 0x7fffffff; // Mask to ensure non-negative 31-bit integer
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}
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/**
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* Calculates theme index from a given item. The identity is computed
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* deterministically from the dataKey string, ensuring stability across renders
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* and module reloads.
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* @param item - The themable item to calculate identity for
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* @param themeCount - Optional number of available themes; if provided, clamps
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* the hash to [0, themeCount).
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*/
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function graphicalItemIdentity(item, themeCount) {
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// Negative or zero themeCount is semantically invalid (can't have negative themes,
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// and zero themes means none available)
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if (themeCount != null && themeCount <= 0) {
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return 0;
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}
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var keyString = String(item.dataKey);
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var hashResult = computeHash(keyString);
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if (themeCount != null && themeCount > 0) {
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return hashResult % themeCount;
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}
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return hashResult;
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} |