billboard.js/src/module/util/brush.ts

Re-usable easy interface JavaScript chart library, based on D3 v4+

/**
 * Copyright (c) 2017 ~ present NAVER Corp.
 * billboard.js project is licensed under the MIT license
 * @ignore
 */
import {brushSelection as d3BrushSelection} from "d3-brush";

/**
 * Return brush selection array
 * @param {object} ctx Current instance
 * @returns {d3.brushSelection}
 * @private
 */
function getBrushSelection(ctx) {
	const {event, $el} = ctx;
	const main = $el.subchart.main || $el.main;
	let selection;

	// check from event
	if (event && event.type === "brush") {
		selection = event.selection;
		// check from brush area selection
	} else if (main && (selection = main.select(".bb-brush").node())) {
		selection = d3BrushSelection(selection);
	}

	return selection;
}

/**
 * Check if brush is empty
 * @param {object} ctx Bursh context
 * @returns {boolean}
 * @private
 */
function brushEmpty(ctx): boolean {
	const selection = getBrushSelection(ctx);

	if (selection) {
		// brush selected area
		// two-dimensional: [[x0, y0], [x1, y1]]
		// one-dimensional: [x0, x1] or [y0, y1]
		return selection[0] === selection[1];
	}

	return true;
}

export {brushEmpty, getBrushSelection};