Rasterizes svg images to (alpha) png with phantomjs

svg2png

#! /usr/bin/env phantomjs
// -*- js2 -*-

var webpage = require('webpage')
  , system = require('system')
  , URL, FILENAME, W, H;
  ;

if (system.args.length < 2 || system.args.length > 5) {
  console.log('Usage: svg2png source.svg output.png [width||?] [height||?]');
  phantom.exit();
}
else {
  URL = system.args[1];
  FILENAME = system.args[2];
  W = Number(system.args[3]);
  H = Number(system.args[4]);
  if (isNaN(W)) W = undefined;
  if (isNaN(H)) H = undefined;
  peek(URL, grabSize);
}

function peek(url, fn) {
  var page = webpage.create();
  page.onConsoleMessage = function(msg) {
    console.log(msg);
  };
  page.open(url, function (status) {
    if (status !== 'success')
      console.log('Unable to load ' + url);
    else
      fn(page);
  });
}

function grabSize(page) {
  page.onConsoleMessage = function(msg) {
    var d = JSON.parse(msg);
    if (!W && !H) { W = d.w; H = d.h; }
    if ( W && !H) { H = W * d.h / d.w; }
    if (!W &&  H) { W = H * d.w / d.h; }
    console.log(JSON.stringify(d), W, H);
    screenshot(URL, FILENAME, W, H);
  };

  page.evaluate(function() {
    var svg = document.documentElement
      , w   = svg.getAttribute('width')
      , h   = svg.getAttribute('height')
      , box = svg.viewBox.animVal
      , b_w = box.width
      , b_h = box.height
      ;

    if (b_w && b_h) {
      if (w && !h) h = w * b_h / b_w;
      if (h && !w) w = h * b_w / b_h;
      if (!w&& !h) {
        w = b_w;
        h = b_h;
      }
    }

    console.log(JSON.stringify({ w: Number(w), h: Number(h) }));
  });
}

function screenshot(url, filename, w, h) {
  var page = webpage.create();
  page.viewportSize = { width: w, height: h };
  page.open(url, function (status) {
    if (status !== 'success') {
      console.log('Unable to load ' + url);
      phantom.exit();
    }
    else {
      window.setTimeout(function () {
        page.render(filename);
        phantom.exit();
      }, 200);
    }
  });
}