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script.js
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script.js
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/**
* Script executed by PhantomJS to generate a chart as an image.
*/
var system = require("system");
var webpage = require("webpage");
var server = require('webserver').create();
var fs = require("fs");
var config = require("./package.json");
phantom.onError = function (msg, trace) {
console.log("Unhandled error: " + createErrorMessage(msg, trace));
phantom.exit(1);
};
if (system.args.length !== 3) {
console.log("Usage: script.js <portnumber> <path-to-chartjs>");
phantom.exit(1);
}
var port = system.args[1],
chartJsPath = system.args[2];
if (!fs.exists(chartJsPath)) {
console.log("PhantomJS server could not find Chart.js at path '" + chartJsPath + "'.");
phantom.exit(1);
}
var listening = server.listen(port, handleRequest);
if (!listening) {
console.log("PhantomJS server unable to listen on port " + port + ". Exiting.");
phantom.exit(1);
}
else {
console.log("PhantomJS server listening on port " + port);
}
function handleRequest(request, response) {
if (request.method == "GET" && request.url == "/version") {
response.statusCode = 200;
response.headers = {
"Cache": "no-cache",
"Content-Type": "application/json"
};
response.write(JSON.stringify({ version: config.version }));
response.closeGracefully();
return;
}
if (request.method != "POST") {
sendError(response, "Bad Request. Expected POST.", 400);
return;
}
if (request.headers["content-type"] != "application/json") {
sendError(response, "Bad Request. Expected content type of 'application/json'.", 400);
return;
}
render(request.post, function (err, result) {
if (err) {
sendError(response, err);
return;
}
send(response, result);
});
}
function sendError(response, message, statusCode) {
send(response, message, statusCode || 500);
}
function send(response, data, statusCode) {
response.statusCode = statusCode || 200;
response.headers = {
"Cache": "no-cache",
"Content-Type": "text/plain"
};
response.write(data);
response.closeGracefully();
}
function render(configText, callback) {
// parse json
try {
var config = JSON.parse(configText);
}
catch (e) {
callback("Unable to parse chart configuration: " + e.message);
return;
}
// make sure we have a chart object.
if (!config.chart) {
callback("Missing chart configuration.");
return;
}
// make sure we have an options object.
if (!config.chart.options) {
config.chart.options = {};
}
// turn off interactive features of chart.js
config.chart.options.responsive = false;
config.chart.options.animation = false;
// get the width if specified. if not specified, default to 720.
var width = config.width || 720;
// get the height if specified. if height is not specified, calculate using aspect ratio.
var height = config.height || (width / (config.chart.options.aspectRatio || 2));
// get the scale
var scale = config.scale || 1;
var page = webpage.create(),
called = false;
page.onError = function (msg, trace) {
if (!called) {
called = true;
callback(createErrorMessage(msg, trace));
}
};
// Chart.js must be installed as a peer dependency.
page.injectJs(chartJsPath);
// set the viewport size to define the render area
page.viewportSize = {
width: width * scale,
height: height * scale
};
page.evaluate(renderPage, config.chart, width, height, scale);
var data = page.renderBase64(config.type || "PNG");
page.close();
if (!called) {
called = true;
callback(null, data);
}
}
function renderPage(chart, width, height, scale) {
// clear body margin so canvas is positioned at upper left
document.body.style.margin = "0";
// create the canvas
var canvas = document.createElement("canvas");
if (scale == 1) {
canvas.setAttribute("width", width);
canvas.setAttribute("height", height);
}
else {
canvas.setAttribute("width", width * scale);
canvas.setAttribute("height", height * scale);
canvas.getContext("2d").setTransform(scale, 0, 0, scale, 0, 0);
// monkey patch the Chart Controller to reset the calculated height and width so chart renders correctly on the scaled canvas.
var _super = Chart.Controller.prototype.initialize;
Chart.Controller.prototype.initialize = function() {
this.chart.width = width;
this.chart.height = height;
return _super.call(this);
}
}
document.body.appendChild(canvas);
new Chart(canvas, chart);
}
function createErrorMessage(msg, trace) {
var stack = [msg];
if (trace && trace.length) {
trace.forEach(function (t) {
stack.push(" " + t.file + ": " + t.line + (t.function ? " (in function '" + t.function + "')" : ""));
});
}
return stack.join("\n");
}