如何将FabricJS画布中心背景图像？

Question

When adding a backgroundImage to a canvas using setBackgroundImage(), I haven't been able to find a way to center the background image. I need to center it to line it up with the centered paths in the canvas.

The docs http://fabricjs.com/docs/fabric.StaticCanvas.html#setBackgroundImage show various information, but don't seem to specify positioning of the background image in relation to the canvas.

    canvas.setOverlayImage('http://fabricjs.com/assets/honey_im_subtle.png',
        canvas.renderAll.bind(canvas), {
            scaleX:1,
            scaleY:1,
            top: 0,
            left: 0,
            originX: 'center',
            originY: 'center'
    });

This will center the image to the top left corner of the canvas. How do I now specify that the origination point on the canvas should be center/center instead of top/left?

Update: is there a method that will update dynamically if the canvas is resized? Was hoping to use percentage values for top and left, but that doesn't seem to work.

Thanks!

Answer 1

I was able to find a solution that works, but will not update automatically if the canvas is resized:

var center = deviceCanvas.getCenter();
canvas.setOverlayImage('http://fabricjs.com/assets/honey_im_subtle.png',
    canvas.renderAll.bind(canvas), {
        scaleX:1,
        scaleY:1,
        top: center.top,
        left: center.left,
        originX: 'center',
        originY: 'center'
});