zz-chart/lib/strategy/quadtree.js

Alauda Chart components by Alauda Frontend Team

export function pointWithin(px, py, rlft, rtop, rrgt, rbtm) {
    return px >= rlft && px <= rrgt && py >= rtop && py <= rbtm;
}
const MAX_OBJECTS = 10;
const MAX_LEVELS = 4;
export class Quadtree {
    constructor(x, y, width, height, left) {
        this.o = [];
        this.split = () => {
            const { x, y, w: _w, h: _h, l: _l } = this;
            const w = _w / 2;
            const h = _h / 2;
            const l = _l + 1;
            this.q = [
                // top right
                new Quadtree(x + w, y, w, h, l),
                // top left
                new Quadtree(x, y, w, h, l),
                // bottom left
                new Quadtree(x, y + h, w, h, l),
                // bottom right
                new Quadtree(x + w, y + h, w, h, l),
            ];
        };
        this.x = x;
        this.y = y;
        this.w = width;
        this.h = height;
        this.l = left || 0;
    }
    // invokes callback with index of each overlapping quad
    quads(x, y, w, h, cb) {
        const q = this.q;
        const hzMid = this.x + this.w / 2;
        const vtMid = this.y + this.h / 2;
        const startIsNorth = y < vtMid;
        const startIsWest = x < hzMid;
        const endIsEast = x + w > hzMid;
        const endIsSouth = y + h > vtMid;
        // top-right quad
        startIsNorth && endIsEast && cb(q[0]);
        // top-left quad
        startIsWest && startIsNorth && cb(q[1]);
        // bottom-left quad
        startIsWest && endIsSouth && cb(q[2]);
        // bottom-right quad
        endIsEast && endIsSouth && cb(q[3]);
    }
    add(o) {
        if (this.q != null) {
            this.quads(o.x, o.y, o.w, o.h, q => {
                q.add(o);
            });
        }
        else {
            const os = this.o;
            os.push(o);
            if (os.length > MAX_OBJECTS && this.l < MAX_LEVELS) {
                this.split();
                for (const oi of os) {
                    this.quads(oi.x, oi.y, oi.w, oi.h, q => {
                        q.add(oi);
                    });
                }
                this.o.length = 0;
            }
        }
    }
    getQ(x, y, w, h, cb) {
        const os = this.o;
        for (const o of os)
            cb(o);
        if (this.q != null) {
            this.quads(x, y, w, h, q => {
                q.getQ(x, y, w, h, cb);
            });
        }
    }
    clear() {
        this.o.length = 0;
        this.q = null;
    }
}
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