scale.js Example File

  var ctx = document.getElementById('tutorial').getContext('2d');
    ctx.strokeStyle = "#fc0";
    ctx.lineWidth = 1.5;
    ctx.fillRect(0,0,300,300);

    // Uniform scaling
    ctx.save()
    ctx.translate(50,50);
    drawSpirograph(ctx,22,6,5);  // no scaling

    ctx.translate(100,0);
    ctx.scale(0.75,0.75);
    drawSpirograph(ctx,22,6,5);

    ctx.translate(133.333,0);
    ctx.scale(0.75,0.75);
    drawSpirograph(ctx,22,6,5);
    ctx.restore();

    // Non uniform scaling (y direction)
    ctx.strokeStyle = "#0cf";
    ctx.save()
    ctx.translate(50,150);
    ctx.scale(1,0.75);
    drawSpirograph(ctx,22,6,5);

    ctx.translate(100,0);
    ctx.scale(1,0.75);
    drawSpirograph(ctx,22,6,5);

    ctx.translate(100,0);
    ctx.scale(1,0.75);
    drawSpirograph(ctx,22,6,5);
    ctx.restore();

    // Non uniform scaling (x direction)
    ctx.strokeStyle = "#cf0";
    ctx.save()
    ctx.translate(50,250);
    ctx.scale(0.75,1);
    drawSpirograph(ctx,22,6,5);

    ctx.translate(133.333,0);
    ctx.scale(0.75,1);
    drawSpirograph(ctx,22,6,5);

    ctx.translate(177.777,0);
    ctx.scale(0.75,1);
    drawSpirograph(ctx,22,6,5);
    ctx.restore();
  function drawSpirograph(ctx,R,r,O){
    var x1 = R-O;
    var y1 = 0;
    var i  = 1;
    ctx.beginPath();
    ctx.moveTo(x1,y1);
    do {
      if (i>20000) break;
      var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72))
      var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72))
      ctx.lineTo(x2,y2);
      x1 = x2;
      y1 = y2;
      i++;
    } while (x2 != R-O && y2 != 0 );
    ctx.stroke();
  }