Generate placeholder images (nice gradients) for express based node applications. Requires node-canvas.

placeholder.js

var Canvas = require('canvas');


var randomInt = function(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}
var randomColor = function() {
  var color = '#' + randomInt(0, 16777215).toString(16);
  for(var i = 0; i < 7 - color.length; i++) {
    color = color + '0';
  }
  return color;
}


exports.placeholder = function(req, res) {
  var canvas = new Canvas(400, 400);
  var ctx = canvas.getContext('2d');
  var image = new Canvas.Image;

  var offset = randomInt(0, 400);
  var gradient = ctx.createLinearGradient(0, offset, 400, 400 - offset);
  var stepCount = randomInt(1, 3);
  for(var step = 0; step < stepCount ; step++) {
    var color = randomColor();
    gradient.addColorStop(step / (stepCount - 1), color);
  }

  ctx.fillStyle = gradient;
  ctx.fillRect(0, 0, 400, 400);

  res.setHeader('content-type', 'image/png');
  canvas.createPNGStream().pipe(res);
};