aaac7fed
 liuqimichale
add
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import { eventType, style, offsetToBody } from '../util/dom'
import { getDistance } from '../util/lang'
export function zoomMixin(BScroll) {
BScroll.prototype._initZoom = function () {
const {start = 1, min = 1, max = 4} = this.options.zoom
this.scale = Math.min(Math.max(start, min), max)
this.setScale(this.scale)
this.scrollerStyle[style.transformOrigin] = '0 0'
}
BScroll.prototype._zoomTo = function (scale, originX, originY, startScale) {
this.scaled = true
const lastScale = scale / (startScale || this.scale)
this.setScale(scale)
this.refresh()
let newX = Math.round(this.startX - (originX - this.relativeX) * (lastScale - 1))
let newY = Math.round(this.startY - (originY - this.relativeY) * (lastScale - 1))
if (newX > this.minScrollX) {
newX = this.minScrollX
} else if (newX < this.maxScrollX) {
newX = this.maxScrollX
}
if (newY > this.minScrollY) {
newY = this.minScrollY
} else if (newY < this.maxScrollY) {
newY = this.maxScrollY
}
if (this.x !== newX || this.y !== newY) {
this.scrollTo(newX, newY, this.options.bounceTime)
}
this.scaled = false
}
BScroll.prototype.zoomTo = function (scale, x, y) {
let {left, top} = offsetToBody(this.wrapper)
let originX = x + left - this.x
let originY = y + top - this.y
this._zoomTo(scale, originX, originY)
}
BScroll.prototype._zoomStart = function (e) {
const firstFinger = e.touches[0]
const secondFinger = e.touches[1]
const deltaX = Math.abs(firstFinger.pageX - secondFinger.pageX)
const deltaY = Math.abs(firstFinger.pageY - secondFinger.pageY)
this.startDistance = getDistance(deltaX, deltaY)
this.startScale = this.scale
let {left, top} = offsetToBody(this.wrapper)
this.originX = Math.abs(firstFinger.pageX + secondFinger.pageX) / 2 + left - this.x
this.originY = Math.abs(firstFinger.pageY + secondFinger.pageY) / 2 + top - this.y
this.trigger('zoomStart')
}
BScroll.prototype._zoom = function (e) {
if (!this.enabled || this.destroyed || eventType[e.type] !== this.initiated) {
return
}
if (this.options.preventDefault) {
e.preventDefault()
}
if (this.options.stopPropagation) {
e.stopPropagation()
}
const firstFinger = e.touches[0]
const secondFinger = e.touches[1]
const deltaX = Math.abs(firstFinger.pageX - secondFinger.pageX)
const deltaY = Math.abs(firstFinger.pageY - secondFinger.pageY)
const distance = getDistance(deltaX, deltaY)
let scale = distance / this.startDistance * this.startScale
this.scaled = true
const {min = 1, max = 4} = this.options.zoom
if (scale < min) {
scale = 0.5 * min * Math.pow(2.0, scale / min)
} else if (scale > max) {
scale = 2.0 * max * Math.pow(0.5, max / scale)
}
const lastScale = scale / this.startScale
const x = this.startX - (this.originX - this.relativeX) * (lastScale - 1)
const y = this.startY - (this.originY - this.relativeY) * (lastScale - 1)
this.setScale(scale)
this.scrollTo(x, y, 0)
}
BScroll.prototype._zoomEnd = function (e) {
if (!this.enabled || this.destroyed || eventType[e.type] !== this.initiated) {
return
}
if (this.options.preventDefault) {
e.preventDefault()
}
if (this.options.stopPropagation) {
e.stopPropagation()
}
this.isInTransition = false
this.isAnimating = false
this.initiated = 0
const {min = 1, max = 4} = this.options.zoom
const scale = this.scale > max ? max : this.scale < min ? min : this.scale
this._zoomTo(scale, this.originX, this.originY, this.startScale)
this.trigger('zoomEnd')
}
}
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