twitter.js

var Canvas = require('canvas'),
    fs = require('fs'),
    c = new Canvas(1280, 140),
    ctx = c.getContext('2d');

var td = '/Users/tmcw/Dropbox/docs/twitter/tweets/';
var tweets = fs.readdirSync(td);

function sx(x) {
    return ((x / (24 * 60)) * 1280);
}

ctx.fillStyle = '#fff';
ctx.fillRect(0, 0, 1280, 140);
ctx.fillStyle = '#000';

var t;
for (var i = 0; i < 24; i++) {
    if (i == 0) t = '12am';
    else if (i == 12) t = '12pm';
    else if (i > 12) {
        t = (i - 12) + 'pm';
    } else {
        t = (i) + 'am';
    }
    ctx.fillText(t, sx(i * 60), 130);
}

ctx.globalAlpha = 0.1;

tweets.forEach(function(t) {
    var twt = JSON.parse(fs.readFileSync(td + t, 'utf8'));
    var time = new Date(twt.created_at);
    var x = (time.getHours() * 60) + time.getMinutes();
    ctx.fillRect(sx(x), 0, 1, 120);
});

c.toBuffer(function(err, buf) {
    fs.writeFileSync('twitter.png', buf);
});