linechart spline option

.eslintrc.json

@@ -14,7 +14,7 @@
         ],
         "linebreak-style": [
             "error",
-            "unix"
+            "windows"
         ],
         "semi": [
             "error",

.gitignore

@@ -60,4 +60,8 @@ typings/
 # next.js build output
 .next
 
-.DS_Store
+.DS_Store
+
+package-lock.json
+dist/
+docs/assets/js/

src/js/charts/AxisChart.js

@@ -298,6 +298,7 @@ export default class AxisChart extends BaseChart {
 					svgDefs: this.svgDefs,
 					heatline: this.lineOptions.heatline,
 					regionFill: this.lineOptions.regionFill,
+					spline: this.lineOptions.spline,
 					hideDots: this.lineOptions.hideDots,
 					hideLine: this.lineOptions.hideLine,
 

src/js/objects/ChartComponents.js

@@ -368,7 +368,8 @@ let componentConfigs = {
 					c.color,
 					{
 						heatline: c.heatline,
-						regionFill: c.regionFill
+						regionFill: c.regionFill,
+						spline: c.spline
 					},
 					{
 						svgDefs: c.svgDefs,
@@ -419,7 +420,7 @@ let componentConfigs = {
 
 			if(Object.keys(this.paths).length) {
 				animateElements = animateElements.concat(animatePath(
-					this.paths, newXPos, newYPos, newData.zeroLine));
+					this.paths, newXPos, newYPos, newData.zeroLine, this.constants.spline));
 			}
 
 			if(this.units.length) {

src/js/utils/animate.js

@@ -1,4 +1,4 @@
-import { getBarHeightAndYAttr } from './draw-utils';
+import { getBarHeightAndYAttr, createSplineCurve } from './draw-utils';
 
 export const UNIT_ANIM_DUR = 350;
 export const PATH_ANIM_DUR = 350;
@@ -74,13 +74,14 @@ export function animateDot(dot, x, y) {
 	// dot.animate({cy: yTop}, UNIT_ANIM_DUR, mina.easein);
 }
 
-export function animatePath(paths, newXList, newYList, zeroLine) {
+export function animatePath(paths, newXList, newYList, zeroLine, spline) {
 	let pathComponents = [];
+	let pointsStr = newYList.map((y, i) => (newXList[i] + ',' + y)).join("L");
+    
+	if (spline)
+		pointsStr = createSplineCurve(newXList, newYList);
 
-	let pointsStr = newYList.map((y, i) => (newXList[i] + ',' + y));
-	let pathStr = pointsStr.join("L");
-
-	const animPath = [paths.path, {d:"M"+pathStr}, PATH_ANIM_DUR, STD_EASING];
+	const animPath = [paths.path, {d:"M" + pointsStr}, PATH_ANIM_DUR, STD_EASING];
 	pathComponents.push(animPath);
 
 	if(paths.region) {
@@ -89,7 +90,7 @@ export function animatePath(paths, newXList, newYList, zeroLine) {
 
 		const animRegion = [
 			paths.region,
-			{d:"M" + regStartPt + pathStr + regEndPt},
+			{d:"M" + regStartPt + pointsStr + regEndPt},
 			PATH_ANIM_DUR,
 			STD_EASING
 		];
@@ -101,4 +102,4 @@ export function animatePath(paths, newXList, newYList, zeroLine) {
 
 export function animatePathStr(oldPath, pathStr) {
 	return [oldPath, {d: pathStr}, UNIT_ANIM_DUR, STD_EASING];
-}
+}

src/js/utils/draw-utils.js

@@ -52,4 +52,48 @@ export function shortenLargeNumber(label) {
 
 	// Correct for floating point error upto 2 decimal places
 	return Math.round(shortened*100)/100 + ' ' + ['', 'K', 'M', 'B', 'T'][l];
+}
+
+// cubic bezier curve calculation (from example by François Romain)
+export function createSplineCurve(xList, yList) {
+
+	let points=[];
+	for(let i=0;i<xList.length;i++){
+		points.push([xList[i], yList[i]]);
+	}
+
+	let smoothing = 0.2;
+	let line = (pointA, pointB) => {
+		let lengthX = pointB[0] - pointA[0];
+		let lengthY = pointB[1] - pointA[1];
+		return {
+			length: Math.sqrt(Math.pow(lengthX, 2) + Math.pow(lengthY, 2)),
+			angle: Math.atan2(lengthY, lengthX)
+		};
+	};
+    
+	let controlPoint = (current, previous, next, reverse) => {
+		let p = previous || current;
+		let n = next || current;
+		let o = line(p, n);
+		let angle = o.angle + (reverse ? Math.PI : 0);
+		let length = o.length * smoothing;
+		let x = current[0] + Math.cos(angle) * length;
+		let y = current[1] + Math.sin(angle) * length;
+		return [x, y];
+	};
+    
+	let bezierCommand = (point, i, a) => {
+		let cps = controlPoint(a[i - 1], a[i - 2], point);
+		let cpe = controlPoint(point, a[i - 1], a[i + 1], true);
+		return `C ${cps[0]},${cps[1]} ${cpe[0]},${cpe[1]} ${point[0]},${point[1]}`;
+	};
+    
+	let pointStr = (points, command) => {
+		return points.reduce((acc, point, i, a) => i === 0
+			? `${point[0]},${point[1]}`
+			: `${acc} ${command(point, i, a)}`, '');
+	};
+    
+	return pointStr(points, bezierCommand);
 }

src/js/utils/draw.js

@@ -1,4 +1,4 @@
-import { getBarHeightAndYAttr, truncateString, shortenLargeNumber } from './draw-utils';
+import { getBarHeightAndYAttr, truncateString, shortenLargeNumber, createSplineCurve } from './draw-utils';
 import { getStringWidth } from './helpers';
 import { DOT_OVERLAY_SIZE_INCR, PERCENTAGE_BAR_DEFAULT_DEPTH } from './constants';
 import { lightenDarkenColor } from './colors';
@@ -577,6 +577,11 @@ export function datasetDot(x, y, radius, color, label='', index=0) {
 export function getPaths(xList, yList, color, options={}, meta={}) {
 	let pointsList = yList.map((y, i) => (xList[i] + ',' + y));
 	let pointsStr = pointsList.join("L");
+
+	// Spline
+	if (options.spline)
+		pointsStr = createSplineCurve(xList, yList);
+    
 	let path = makePath("M"+pointsStr, 'line-graph-path', color);
 
 	// HeatLine