Multiplier property not working properly in “toDataURL” function with cropping in Fabric.js

问题

My original size of the canvas is 800X700.

I am using clipTo to work in a selected portion of a canvas:

var rect = new fabric.Rect({
  left: 100,
  top: 50,
  fill: '#fff',
  width: 376,
  height: 602,
  strokeWidth: 0,
  selectable: false
});

rect.set({
    clipFor: 'mainCanvas',
});

I make sure all the images and text fall within this portion of the canvas.

What I want to Do:

I want to scale up this portion of canvas to a width and height of 1500X2400 so that it can be used for printing

I am using the below toDataURL function with multiplier as 3

var imgData= canvas.toDataURL({
  format: 'png',
  width: 376,
  height: 602,
  top: 50,
  left: 100,
  multiplier: 3
});

But I am getting only top most portion of the image. Any solution?

---

Update: More info about the problem

I am using Ubuntu 16.04 and Fabric.js-1.6.2

Demonstrating the problem on JsFiddle

When I click on the enhance image button, only the top left portion of the image is displayed.

来源：https://stackoverflow.com/questions/39387332/multiplier-property-not-working-properly-in-todataurl-function-with-cropping-i