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Implement Pinch gesture for zoom on mobile #3

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merged 1 commit into from
Jun 23, 2018
Merged

Implement Pinch gesture for zoom on mobile #3

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92 changes: 73 additions & 19 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ class Cropper extends React.Component {
imageSize = { width: 0, height: 0, naturalWidth: 0, naturalHeight: 0 }
dragStartPosition = { x: 0, y: 0 }
dragStartCrop = { x: 0, y: 0 }
lastPinchDistance = 0
rafTimeout = null
state = {
cropSize: null,
Expand All @@ -30,10 +31,10 @@ class Cropper extends React.Component {
}

cleanEvents = () => {
document.removeEventListener('mousemove', this.onDrag)
document.removeEventListener('touchmove', this.onDrag)
document.removeEventListener('mouseup', this.dragStopped)
document.removeEventListener('touchend', this.dragStopped)
document.removeEventListener('mousemove', this.onMouseMove)
document.removeEventListener('mouseup', this.onDragStopped)
document.removeEventListener('touchmove', this.onTouchMove)
document.removeEventListener('touchend', this.onDragStopped)
}

onImgLoad = () => {
Expand Down Expand Up @@ -65,27 +66,50 @@ class Cropper extends React.Component {
}
}

static getEventXY = e => ({
x: Number(e.clientX || (e.touches && e.touches[0].clientX)),
y: Number(e.clientY || (e.touches && e.touches[0].clientY)),
static getMousePoint = e => ({ x: Number(e.clientX), y: Number(e.clientY) })

static getTouchPoint = touch => ({
x: Number(touch.clientX),
y: Number(touch.clientY),
})

dragStart = e => {
onMouseDown = e => {
e.preventDefault()
document.addEventListener('mousemove', this.onMouseMove)
document.addEventListener('mouseup', this.onDragStopped)
this.onDragStart(Cropper.getMousePoint(e))
}

onMouseMove = e => this.onDrag(Cropper.getMousePoint(e))

onTouchStart = e => {
e.preventDefault()
const { x, y } = Cropper.getEventXY(e)
document.addEventListener('touchmove', this.onTouchMove)
document.addEventListener('touchend', this.onDragStopped)
if (e.touches.length === 2) {
this.onPinchStart(e)
} else if (e.touches.length === 1) {
this.onDragStart(Cropper.getTouchPoint(e.touches[0]))
}
}

onTouchMove = e => {
if (e.touches.length === 2) {
this.onPinchMove(e)
} else if (e.touches.length === 1) {
this.onDrag(Cropper.getTouchPoint(e.touches[0]))
}
}

onDragStart = ({ x, y }) => {
this.dragStartPosition = { x, y }
this.dragStartCrop = { x: this.props.crop.x, y: this.props.crop.y }
document.addEventListener('mousemove', this.onDrag)
document.addEventListener('touchmove', this.onDrag)
document.addEventListener('mouseup', this.dragStopped)
document.addEventListener('touchend', this.dragStopped)
}

onDrag = e => {
onDrag = ({ x, y }) => {
if (this.rafTimeout) window.cancelAnimationFrame(this.rafTimeout)

this.rafTimeout = window.requestAnimationFrame(() => {
const { x, y } = Cropper.getEventXY(e)
if (x === undefined || y === undefined) return
const offsetX = x - this.dragStartPosition.x
const offsetY = y - this.dragStartPosition.y
Expand All @@ -107,15 +131,41 @@ class Cropper extends React.Component {
})
}

dragStopped = () => {
onDragStopped = () => {
this.cleanEvents()
this.emitCropData()
}

static getDistanceBetweenPoints = (pointA, pointB) =>
Math.sqrt(Math.pow(pointA.y - pointB.y, 2) + Math.pow(pointA.x - pointB.x, 2))

onPinchStart(e) {
const pointA = Cropper.getTouchPoint(e.touches[0])
const pointB = Cropper.getTouchPoint(e.touches[1])
this.lastPinchDistance = Cropper.getDistanceBetweenPoints(pointA, pointB)
}

onPinchMove(e) {
if (this.rafTimeout) window.cancelAnimationFrame(this.rafTimeout)
this.rafTimeout = window.requestAnimationFrame(() => {
const pointA = Cropper.getTouchPoint(e.touches[0])
const pointB = Cropper.getTouchPoint(e.touches[1])
const distance = Cropper.getDistanceBetweenPoints(pointA, pointB)

const newZoom = (this.props.zoom * distance) / this.lastPinchDistance
this.setNewZoom(newZoom)
this.lastPinchDistance = distance
})
}

onWheel = e => {
e.preventDefault()
let newZoom = this.props.zoom - e.deltaY / 200
newZoom = Math.min(MAX_ZOOM, Math.max(newZoom, MIN_ZOOM))
const newZoom = this.props.zoom - e.deltaY / 200
this.setNewZoom(newZoom)
}

setNewZoom = zoom => {
const newZoom = Math.min(MAX_ZOOM, Math.max(zoom, MIN_ZOOM))
this.props.onZoomChange && this.props.onZoomChange(newZoom)
}

Expand Down Expand Up @@ -183,7 +233,11 @@ class Cropper extends React.Component {
zoom,
} = this.props
return (
<Container onMouseDown={this.dragStart} onTouchStart={this.dragStart} onWheel={this.onWheel}>
<Container
onMouseDown={this.onMouseDown}
onTouchStart={this.onTouchStart}
onWheel={this.onWheel}
>
<Img
src={this.props.image}
innerRef={el => (this.image = el)}
Expand Down