chartjs-node-canvas
Version:
A node renderer for Chart.js using canvas.
95 lines • 4.46 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
const canvas_1 = require("canvas");
const fresh = require("fresh-require");
class CanvasRenderService {
/**
* Create a new instance of CanvasRenderService.
*
* @param width The width of the charts to render, in pixels.
* @param height The height of the charts to render, in pixels.
* @param chartCallback optional callback which is called once with a new ChartJS global reference.
* @param type optional The canvas type ('PDF' or 'SVG'), see the [canvas pdf doc](https://github.com/Automattic/node-canvas#pdf-output-support).
*/
constructor(width, height, chartCallback, type) {
this._width = width;
this._height = height;
this._ChartJs = fresh('chart.js', require);
this._type = type;
if (chartCallback) {
chartCallback(this._ChartJs);
}
}
/**
* Render to a data url as png.
* @see https://github.com/Automattic/node-canvas#canvastodataurl
*
* @param configuration The Chart JS configuration for the chart to render.
* @param mimeType The image format, `image/png` or `image/jpeg`.
*/
renderToDataURL(configuration, mimeType = 'image/png') {
const chart = this.renderChart(configuration);
return new Promise((resolve, reject) => {
const canvas = chart.canvas;
canvas.toDataURL(mimeType, (error, png) => {
if (error) {
return reject(error);
}
return resolve(png);
});
});
}
/**
* Render to a buffer as png.
* @see https://github.com/Automattic/node-canvas#canvastobuffer
*
* @param configuration The Chart JS configuration for the chart to render.
* @param mimeType A string indicating the image format. Valid options are `image/png`, `image/jpeg` (if node-canvas was built with JPEG support), `raw` (unencoded ARGB32 data in native-endian byte order, top-to-bottom), `application/pdf` (for PDF canvases) and image/svg+xml (for SVG canvases). Defaults to `image/png` for image canvases, or the corresponding type for PDF or SVG canvas.
*/
renderToBuffer(configuration, mimeType = 'image/png') {
const chart = this.renderChart(configuration);
return new Promise((resolve, reject) => {
const canvas = chart.canvas;
canvas.toBuffer((error, buffer) => {
if (error) {
return reject(error);
}
return resolve(buffer);
}, mimeType);
});
}
/**
* Render to a stream as png.
* @see https://github.com/Automattic/node-canvas#canvascreatepngstream
*
* @param configuration The Chart JS configuration for the chart to render.
* @param mimeType A string indicating the image format. Valid options are `image/png`, `image/jpeg` (if node-canvas was built with JPEG support), `application/pdf` (for PDF canvases) and image/svg+xml (for SVG canvases). Defaults to `image/png` for image canvases, or the corresponding type for PDF or SVG canvas.
*/
renderToStream(configuration, mimeType = 'image/png') {
const chart = this.renderChart(configuration);
const canvas = chart.canvas;
switch (mimeType) {
case 'image/png':
return canvas.createPNGStream();
case 'image/jpeg':
return canvas.createJPEGStream();
case 'application/pdf':
return canvas.createPDFStream();
default:
throw new Error(`Un-handled mimeType: ${mimeType}`);
}
}
renderChart(configuration) {
const canvas = canvas_1.createCanvas(this._width, this._height, this._type);
canvas.style = {};
// Disable animation (otherwise charts will throw exceptions)
configuration.options = configuration.options || {};
configuration.options.responsive = false;
configuration.options.animation = false;
const context = canvas.getContext('2d');
global.window = {}; //https://github.com/chartjs/Chart.js/pull/5324
return new this._ChartJs(context, configuration);
}
}
exports.CanvasRenderService = CanvasRenderService;
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