Creative Coding: Visual Experiments & Information Pipeline

an ongoing coding and research seminar

Draw a circle line by line (SVG)

$(document).ready(function(){

  $board = $('#board');

  var origin_x = $(window).width() / 2;
  var origin_y = $(window).height() / 2;
  var radius = $(window).width(); //800;
  var all_lines = [];
  var circle_loop = 0;
  var adding_lines = setInterval(add_a_line, 10);
  var steps_increment = 1000;
  var ii = 0;
  var colours = ['red','orange','yellow','green','blue','black', 'white'];

  function add_a_line() {
    ii++;
    if (ii > 6500) {
      exportSVG();
      clearInterval(adding_lines);
    }

    circle_loop = circle_loop + 1/(steps_increment/10); ///steps_increment;
    var pointA_x = origin_x+(radius * Math.cos(circle_loop));
    var pointA_y = origin_y+(radius * Math.sin(circle_loop));
    pointA_x = Math.round(pointA_x * 100) / 100;
    pointA_y = Math.round(pointA_y * 100) / 100;
    var single_line = pointA_x+","+pointA_y+" "
      +origin_x+","+origin_y+"";

    var stroke_color = colours[ Math.floor(circle_loop*steps_increment) % colours.length ];
    var one_line = {points: single_line, color:'transparent', stroke_color: stroke_color, stroke_width:0.2};
    $line = $(document.createElementNS("http://www.w3.org/2000/svg", "polygon")).attr({
        "points": one_line.points,
        "style": "fill:"+one_line.color+";stroke:"+one_line.stroke_color+";stroke-width:"+one_line.stroke_width+";fill-rule:nonzero;"
        });
    $board.append($line);
  }

  //
  
});

var exportSVG = function(svg = $('#board').get(0) ) {
  // first create a clone of our svg node so we don't mess the original one
  var clone = svg.cloneNode(true);
  // parse the styles
  parseStyles(clone);

  // create a doctype
  var svgDocType = document.implementation.createDocumentType('svg', "-//W3C//DTD SVG 1.1//EN", "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd");
  // a fresh svg document
  var svgDoc = document.implementation.createDocument('http://www.w3.org/2000/svg', 'svg', svgDocType);
  // replace the documentElement with our clone 
  svgDoc.replaceChild(clone, svgDoc.documentElement);
  // get the data
  var svgData = (new XMLSerializer()).serializeToString(svgDoc);

  // now you've got your svg data, the following will depend on how you want to download it
  // e.g yo could make a Blob of it for FileSaver.js
  /*
  var blob = new Blob([svgData.replace(/></g, '>\n\r<')]);
  saveAs(blob, 'myAwesomeSVG.svg');
  */
  // here I'll just make a simple a with download attribute

  var a = document.createElement('a');
  a.href = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(svgData.replace(/></g, '>\n\r<'));
  a.download = 'myAwesomeSVG.svg';
  a.innerHTML = 'download the svg file';
  document.body.appendChild(a);

};

var parseStyles = function(svg) {
  var styleSheets = [];
  var i;
  // get the stylesheets of the document (ownerDocument in case svg is in <iframe> or <object>)
  var docStyles = svg.ownerDocument.styleSheets;

  // transform the live StyleSheetList to an array to avoid endless loop
  for (i = 0; i < docStyles.length; i++) {
    styleSheets.push(docStyles[i]);
  }

  if (!styleSheets.length) {
    return;
  }

  var defs = svg.querySelector('defs') || document.createElementNS('http://www.w3.org/2000/svg', 'defs');
  if (!defs.parentNode) {
    svg.insertBefore(defs, svg.firstElementChild);
  }
  svg.matches = svg.matches || svg.webkitMatchesSelector || svg.mozMatchesSelector || svg.msMatchesSelector || svg.oMatchesSelector;


  // iterate through all document's stylesheets
  for (i = 0; i < styleSheets.length; i++) {
    var currentStyle = styleSheets[i]

    var rules;
    try {
      rules = currentStyle.cssRules;
    } catch (e) {
      continue;
    }
    // create a new style element
    var style = document.createElement('style');
    // some stylesheets can't be accessed and will throw a security error
    var l = rules && rules.length;
    // iterate through each cssRules of this stylesheet
    for (var j = 0; j < l; j++) {
      // get the selector of this cssRules
      var selector = rules[j].selectorText;
      // probably an external stylesheet we can't access
      if (!selector) {
        continue;
      }

      // is it our svg node or one of its children ?
      if ((svg.matches && svg.matches(selector)) || svg.querySelector(selector)) {

        var cssText = rules[j].cssText;
        // append it to our <style> node
        style.innerHTML += cssText + '\n';
      }
    }
    // if we got some rules
    if (style.innerHTML) {
      // append the style node to the clone's defs
      defs.appendChild(style);
    }
  }

};