Function fetchData

test/node/scatter-gps.js:87–118

(idx)

var CHUNK_COUNT = 229;
// https://blog.openstreetmap.org/2012/04/01/bulk-gps-point-data/
function fetchData(idx) {
    if (idx >= CHUNK_COUNT) {
        setTimeout(function () {
            fs.writeFile('out.png', canvas.toBuffer());
            chart.dispose();
        });
        return;
    }

    fs.readFile(`../../../echarts-gl/test/data/gps/gps_${idx}.bin`, function (err, buffer) {
        var arr = new Uint8Array(buffer.length);
        for (var i = 0; i < buffer.length; i++) {
            arr[i] = buffer[i];
        }

        var rawData = new Int32Array(arr.buffer);
        var data = new Float32Array(rawData.length);
        for (var i = 0; i < rawData.length; i += 2) {
            data[i] = rawData[i+1] / 1e7;
            data[i+1] = rawData[i] / 1e7;
        }

        chart.appendData({
            seriesIndex: 0,
            data: data
        });

        fetchData(idx + 1);

        progress.tick();
    });
}
var progress = new ProgressBar('Generating [:bar] :percent :etas', {
    complete: '=',
    incomplete: ' ',