CreateJSラジアルグラデーションとマトリックス

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var horizontalScale = .3;
var verticalScale = 1;

var gradient = ctx.createRadialGradient(100/horizontalScale, 100/verticalScale, 100, 100/horizontalScale,100/verticalScale,0);
gradient.addColorStop(0,"green");
gradient.addColorStop(1,"red");

// shrink the context's matrix
ctx.scale(horizontalScale, verticalScale)
// draw your gradient
ctx.fillStyle = gradient;
// stretch the rectangle which contains the gradient accordingly
ctx.fillRect(0,0, 200/horizontalScale, 200/verticalScale);
// reset the context's matrix
ctx.setTransform(1,0,0,1,0,0);

canvas{ background-color: ivory;}

<canvas id="canvas" width="200" height="200"></canvas>

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

function shrinkedRadial(ctx, shapeArray, xScale, yScale, gradientOpts) {

    // scaling by 0 is like not drawing
    if (!xScale || !yScale) return;

    var gO = gradientOpts;
    // apply our scale on the gradient options we passed
    var gradient = ctx.createRadialGradient(gO.x0 / xScale, gO.y0 / yScale, gO.r0, gO.x1 / xScale, gO.y1 / yScale, gO.r1);
    gradient.addColorStop(gO.c1_pos, gO.c1_fill);
    gradient.addColorStop(gO.c2_pos, gO.c2_fill);

    // shrink the context's matrix
    ctx.scale(xScale, yScale);

    ctx.fillStyle = gradient;
    // execute the drawing operations' string
    shapeArray.forEach(function(str) {
      var val = str.split(' ');
      var op = shapesRef[val[0]];
      if (val[1]) {
        var pos = val[1].split(',').map(function(v, i) {
          // if even, it should be an y axis, otherwise an x one
          return i % 2 ? v / yScale : v / xScale;
        });
        ctx[op].apply(ctx, pos);
      } else {
        // no parameters
        ctx[op]();
      }
    });
    // apply our gradient
    ctx.fill();
    // reset the transform matrix
    ctx.setTransform(1, 0, 0, 1, 0, 0);
  }

// just for shortening our shape drawing operations
// notice how arc operations are omitted, it could be implemented but...
var shapesRef = {
  b: 'beginPath',
  fR: 'fillRect',
  m: 'moveTo',
  l: 'lineTo',
  bC: 'bezierCurveTo',
  qC: 'quadraticCurveTo',
  r: 'rect',
  c: 'closePath'
};

var gradientOpts = {
  x0: 232,
  y0: 55,
  r0: 70,
  x1: 232,
  y1: 55,
  r1: 0,
  c1_fill: 'red',
  c1_pos: 0,
  c2_fill: 'green',
  c2_pos: 1
}

var shapes = ['b', 'm 228,133', 'bC 209,121,154,76,183,43', 'bC 199,28,225,34,233,59', 'bC 239,34,270,29,280,39', 'bC 317,76,248,124,230,133']

// our shape is drawn at 150px from the right so we do move the context accordingly, but you won't have to.
ctx.translate(-150, 0);

shrinkedRadial(ctx, shapes, .3, 1, gradientOpts);

ctx.font = '15px sans-serif';
ctx.fillStyle = 'black';
ctx.fillText('shrinked radialGradient', 3, 20);

// how it looks like without scaling : 

ctx.translate(50, 0)

var gO = gradientOpts;
var gradient = ctx.createRadialGradient(gO.x0, gO.y0, gO.r0, gO.x1, gO.y1, gO.r1);
gradient.addColorStop(gO.c1_pos, gO.c1_fill);
gradient.addColorStop(gO.c2_pos, gO.c2_fill);

ctx.fillStyle = gradient;

shapes.forEach(function(str) {
  var val = str.split(' ');
  var op = shapesRef[val[0]];
  if (val[1]) {
    var pos = val[1].split(',');
    ctx[op].apply(ctx, pos);
  } else {
    ctx[op]();
  }
});
ctx.fill();
ctx.font = '15px sans-serif';
ctx.fillStyle = 'black';
ctx.fillText('normal radialGradient', 160, 20);

<canvas id="canvas" width="400" height="150"></canvas>