fabricjs平移边界限制

Question

缩放时如何设置背景边界限制

我的代码演示jsfiddle link！

canvas.on('mouse:move', (e)=>{
    if (panning && e && e.e && e.e.movementX && canvas.getZoom() > 1) {
        var units = 10;
        var delta = new fabric.Point(e.e.movementX, e.e.movementY);
        canvas.relativePan(delta);
    }

        if (!drawLineTemp.status) return;
        var pointer = canvas.getPointer(e.e);
        this.linerDraw.set({ x2: pointer.x, y2: pointer.y });
        canvas.renderAll();
});