113 lines
3.3 KiB
TypeScript
113 lines
3.3 KiB
TypeScript
import { FolkSet } from './folk-set';
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import { Vertex, verticesToPolygon } from './arrows/utils';
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declare global {
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interface HTMLElementTagNameMap {
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'folk-hull': FolkHull;
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}
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}
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export class FolkHull extends FolkSet {
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static tagName = 'folk-hull';
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#hull: Vertex[] = [];
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get hull(): ReadonlyArray<Vertex> {
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return this.#hull;
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}
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update() {
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if (this.sourcesMap.size === 0) {
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this.style.clipPath = '';
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return;
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}
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const rects = Array.from(this.sourcesMap.values());
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this.#hull = makeHull(rects);
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this.style.clipPath = verticesToPolygon(this.#hull);
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}
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}
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/* This code has been modified from the original source, see the original source below. */
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/*
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* Convex hull algorithm - Library (TypeScript)
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*
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* Copyright (c) 2021 Project Nayuki
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* https://www.nayuki.io/page/convex-hull-algorithm
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program (see COPYING.txt and COPYING.LESSER.txt).
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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function comparePoints(a: Vertex, b: Vertex): number {
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if (a.x < b.x) return -1;
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if (a.x > b.x) return 1;
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if (a.y < b.y) return -1;
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if (a.y > b.y) return 1;
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return 0;
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}
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export function makeHull(rects: DOMRectReadOnly[]): Vertex[] {
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const points: Vertex[] = rects
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.flatMap((rect) => [
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{ x: rect.left, y: rect.top },
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{ x: rect.right, y: rect.top },
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{ x: rect.left, y: rect.bottom },
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{ x: rect.right, y: rect.bottom },
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])
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.sort(comparePoints);
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if (points.length <= 1) return points;
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// Andrew's monotone chain algorithm. Positive y coordinates correspond to "up"
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// as per the mathematical convention, instead of "down" as per the computer
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// graphics convention. This doesn't affect the correctness of the result.
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const upperHull: Array<Vertex> = [];
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for (let i = 0; i < points.length; i++) {
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const p: Vertex = points[i];
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while (upperHull.length >= 2) {
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const q: Vertex = upperHull[upperHull.length - 1];
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const r: Vertex = upperHull[upperHull.length - 2];
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if ((q.x - r.x) * (p.y - r.y) >= (q.y - r.y) * (p.x - r.x)) upperHull.pop();
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else break;
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}
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upperHull.push(p);
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}
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upperHull.pop();
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const lowerHull: Array<Vertex> = [];
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for (let i = points.length - 1; i >= 0; i--) {
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const p: Vertex = points[i];
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while (lowerHull.length >= 2) {
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const q: Vertex = lowerHull[lowerHull.length - 1];
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const r: Vertex = lowerHull[lowerHull.length - 2];
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if ((q.x - r.x) * (p.y - r.y) >= (q.y - r.y) * (p.x - r.x)) lowerHull.pop();
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else break;
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}
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lowerHull.push(p);
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}
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lowerHull.pop();
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if (
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upperHull.length === 1 &&
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lowerHull.length === 1 &&
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upperHull[0].x === lowerHull[0].x &&
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upperHull[0].y === lowerHull[0].y
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)
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return upperHull;
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return upperHull.concat(lowerHull);
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}
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