Element.drag() is working well on the PC, but not working well on the pad. about snap.svg

[qiuliang1108]

let c1 = Snap('#svg')
.paper.rect(0, 0, boxHeight, boxWidth)
.attr({
id: item.uuid,
fill: 'rgb(220, 189, 149)',
stroke: 'rgba(102, 102, 102, 1)',
strokeLinecap: 'square',
strokeWidth: 1,
class: box-${item.sort}
})

let c2 = Snap('#svg').paper.text(boxHeight / 2, boxWidth / 2, item.sort)

Snap('#svg')
.paper.g(c1, c2)
.drag()
.click(function () {
vm.dealWithClickBox(item.uuid, this)
})

[qiuliang1108]

customDrag(ele) {
let move = function (dx, dy, x, y) {
let clientX, clientY
if (typeof dx == 'object' && dx.type == 'touchmove') {
clientX = dx.changedTouches[0].clientX
clientY = dx.changedTouches[0].clientY
dx = clientX - this.data('ox')
dy = clientY - this.data('oy')
}
this.attr({
transform: this.data('origTransform') + (this.data('origTransform') ? 'T' : 't') + [dx, dy]
})
}

		let start = function (x, y, ev) {
			// debugger
			if (typeof x == 'object' && x.type == 'touchstart') {
				x.preventDefault()
				this.data('ox', x.changedTouches[0].clientX)
				this.data('oy', x.changedTouches[0].clientY)
			}
			this.data('origTransform', this.transform().local)
		}

		let stop = function () {}

		// pad上拖拽
		ele.touchstart( start );
		ele.touchmove( move );
		ele.touchend( stop );

		// 电脑上拖拽
		ele.drag(move, start, stop)
	},