trianglifoid.js

/* jshint esnext:true */

var debug = typeof v8debug === 'object';
var express = require('express');
var Trianglify = require('trianglify');
var XMLSerializer = require('xmlserializer');
var cluster = require('express-cluster');
var Cache = require("file-system-cache").default;

 
const cache = Cache({
  basePath: "/tmp/trianglifoid.cache",  
  ns: "trianglifoid"  
});


function main(){
    var app = express();
    app.get('/trianglify', function(req, res) {
        res.setHeader("Content-Type", "image/svg+xml");
        var article_id = req.query.id;
        if (article_id === undefined){
            article_id = 1;
        }
        cache.get(article_id)
            .then(function(result){
                if (!result) throw new Error('undef');
                return res.send(result)
            })            
            .catch(function(err){
                var cell_size = 16 + (2 ^ article_id) % 84;
                var variance = ((2 ^ article_id) % 128) * 1.0 / 128;
                var stroke_width = ((2 ^ article_id) % 128) * 12.0 / 128;
                var colorbrewer_names = [
                    'YlGn', 'YlGnBu', 'GnBu', 'BuGn', 'PuBuGn', 'PuBu',
                    //'BuPu',
                    'RdPu',
                        'PuRd', 'OrRd', 'YlOrRd', 'YlOrBr', 'Purples', 'Blues', 'Greens',
                        'Oranges', 'Reds', 'Greys', 'PuOr', 'BrBG', 'PRGn', 'PiYG',
                        'RdBu', 'RdGy', 'RdYlBu', 'Spectral', 'RdYlGn', 'Accent', 'Dark2',
                        'Paired', 'Pastel1', 'Pastel2', 'Set1', 'Set2', 'Set3'
                ];
                var color_name = colorbrewer_names[(2 ^ article_id) % colorbrewer_names.length];
                var pattern = Trianglify({
                    cell_size: cell_size,
                    variance: variance,
                    x_colors: color_name,
                    y_colors: 'match_x',
                    palette: Trianglify.colorbrewer,
                    stroke_width: stroke_width,
                    width: 256*3,
                    height: 256*1
                });
                var strip_svg = /<[/]?svg[^>]*>/g
                var svg_pattern = XMLSerializer.serializeToString(pattern.svg()).replace(strip_svg, '');
                //var svg_pattern = svg_pattern.replace(strip_svg, '');
                var fullsvg = '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="1536" height="512"> \
<defs> \
  <clipPath id="cut-block"> \
    <rect x="0" y="0" width="768" height="256" /> \
  </clipPath> \
  <g id="original" clip-path="url(#cut-block)"> ' + svg_pattern + ' \
</g>  \
</defs> \
<use xlink:href="#original" transform="scale(1, 1) translate(0 0)"/>  \
<use xlink:href="#original" transform="scale(1, -1) translate(0 -512)"/>  \
<use xlink:href="#original" transform="scale(-1, 1) translate(-1536 0)"/>  \
<use xlink:href="#original" transform="scale(-1, -1) translate(-1536 -512)"/>  \
</svg>'
                cache.save([{key: article_id, value: fullsvg}]);
                return res.send(fullsvg);
        });
    });

    app.listen(8088);
}

if (debug){
    main();
} 
else {
    cluster(function(worker) {
    main();
    }); 
}