How to draw a simple path with animation in Raphaël.js

Question

I am trying to draw a simple path with animation from start to end of a path using the Raphaël.js library at this Demo.

var canvas = Raphael('canvas', 900, 648);
var pathString = "M 200,200 L200,10 L100,10";

$('#start').click(function(e) {
       var line = canvas.path(pathString).attr({ stroke: "#000" });
       line.animate({     },5000);
});

but not sure how to use the animate() function here. How can I achieve this?

Answer 1

There may be a better way to do this, but here is the best I can find: getSubpath allows retrieving a segment of a path. By implementing a custom property which can be animated, we can control the path based on the value of this property:

var canvas = Raphael('canvas', 900, 648);
var pathString = "M 200,200 L200,10 L100,10";

canvas.customAttributes.subpath = function (from, to) {
  from = Math.floor(from);
  to = Math.floor(to);
  if(to < from)
    to = from;
  return {path: this.parentPath.getSubpath(from, to)};
};

$('#start').click(function(e) {
  canvas.clear();
  // Create an invisible full representation of the path
  var completeLine = canvas.path(pathString).attr({ 'stroke-opacity': 0 });
  var len = completeLine.getTotalLength(pathString);

  // Create a partial representation of the path
  var line = canvas.path(pathString);
  line.parentPath = completeLine;
  line.attr({ stroke: "#000", subpath: [0, 0]});

  // Animate using our custom subpath attribute from 0 to the length of the full path
  line.animate({ subpath: [0, len] }, 5000);
});

https://jsfiddle.net/r40k0kjv/5/