Recharts component to PNG
I was able to solve my problem by delving into the Recharts component. Recharts renders as an SVG under a wrapper so all I had to do was convert properly to save as both HTML or SVG
// Exports the graph as embedded JS or PNG
exportChart(asSVG) {
// A Recharts component is rendered as a div that contains namely an SVG
// which holds the chart. We can access this SVG by calling upon the first child/
let chartSVG = ReactDOM.findDOMNode(this.currentChart).children[0];
if (asSVG) {
let svgURL = new XMLSerializer().serializeToString(chartSVG);
let svgBlob = new Blob([svgURL], {type: "image/svg+xml;charset=utf-8"});
FileSaver.saveAs(svgBlob, this.state.uuid + ".svg");
} else {
let svgBlob = new Blob([chartSVG.outerHTML], {type: "text/html;charset=utf-8"});
FileSaver.saveAs(svgBlob, this.state.uuid + ".html");
}
}
I am using FileSaver.js for the save prompt.
This function takes SVG element on input and transforms to image/png
data:
export const svgToPng = (svg, width, height) => {
return new Promise((resolve, reject) => {
let canvas = document.createElement('canvas');
canvas.width = width;
canvas.height = height;
let ctx = canvas.getContext('2d');
// Set background to white
ctx.fillStyle = '#ffffff';
ctx.fillRect(0, 0, width, height);
let xml = new XMLSerializer().serializeToString(svg);
let dataUrl = 'data:image/svg+xml;utf8,' + encodeURIComponent(xml);
let img = new Image(width, height);
img.onload = () => {
ctx.drawImage(img, 0, 0);
let imageData = canvas.toDataURL('image/png', 1.0);
resolve(imageData)
}
img.onerror = () => reject();
img.src = dataUrl;
});
};
And how to access the Recharts SVG element? This code snippet allows you to render any Chart outside of your current visible DOM and use it's SVG:
const exportChart = () => {
// Output image size
const WIDTH = 900;
const HEIGHT = 250;
const convertChart = async (ref) => {
if (ref && ref.container) {
let svg = ref.container.children[0];
let pngData = await svgToPng(svg, WIDTH, HEIGHT);
console.log('Do what you need with PNG', pngData);
}
};
const chart = <LineChart data={...} width={WIDTH} height={HEIGHT}
ref={ref => convertChart(ref)} />;
// Render chart component into helper div
const helperDiv = document.createElement('tmp');
ReactDOM.render(chart, helperDiv);
}