微信小程序 图片裁剪工具，简单易用
项目需求
在做微信小程序的时候有个图片上传之前裁剪的需求，找过一些github中的项目，都不太理想，主要是没有办法自定义宽高，于是自己研究了一下，做了一个简单的图片裁剪效果
使用方法
项目里面直接放的该功能的文件，将这个文件夹复制到小程序项目中，在app.json中启动该页面即可看到效果
微信小程序技术比较新，所以在网上找了很久都没有找到理想的裁剪插件，正好这两天不是很忙就自己查找资料做了，经过一天的努力终于把它做出来了，不容易啊，现在把它分享给你们（可为你门节省一天开发时间哦）：
wxml：
<!--图片展示 -->
<view bindtap='upEwm' data-which='1' >
<view>第一个图</view>
<image style='200rpx;height:200rpx;background-color:red' src='{{headImg}}'></image>
</view>
<view bindtap='upEwm' data-which='2' >
<view>第二个图</view>
<image style='200rpx;height:200rpx;background-color:red' src='{{ewmImg}}'></image>
</view>
<!--裁剪图片浮层-->
<view class='fixed-upimg' wx:if="{{imageFixed}}">
<view class="wx-content-info" >
<!-- <view class="wx-content-info" wx:if="{{imageSrc}}"> -->
<view wx:if="{{isShowImg}}" class="wx-corpper" style="{{cropperInitW}}rpx;height:{{cropperInitH}}rpx;background:#000">
<view bindtap='upLoad' class="wx-corpper-content" style="{{cropperW}}rpx;height:{{cropperH}}rpx;left:{{cropperL}}rpx;top:{{cropperT}}rpx">
<image src="{{imageSrc}}" style="{{cropperW}}rpx;height:{{cropperH}}rpx"></image>
<view class="wx-corpper-crop-box" bindtouchstart="contentStartMove" bindtouchmove="contentMoveing" style="{{cutW}}rpx;height:{{cutH}}rpx;left:{{cutL}}rpx;top:{{cutT}}rpx">
<view class="wx-cropper-view-box">
<!-- <view class="wx-cropper-viewer">
<image src="{{imageSrc}}" style="{{cropperW}}rpx;height:{{cropperH}}rpx;left:{{cropperL - cutL}}rpx;top:{{cropperT - cutT}}rpx"></image>
</view> -->
<view class="wx-cropper-dashed-h"></view>
<view class="wx-cropper-dashed-v"></view>
<view class="wx-cropper-line-t" data-drag="top" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-line-r" data-drag="right" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-line-b" data-drag="bottom" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-line-l" data-drag="left" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-t" data-drag="top" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-tr" data-drag="topTight"></view>
<view class="wx-cropper-point point-r" data-drag="right" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-rb" data-drag="rightBottom" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-b" data-drag="bottom" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-bl" data-drag="bottomLeft"></view>
<view class="wx-cropper-point point-l" data-drag="left" catchtouchstart="dragStart" catchtouchmove="dragMove"></view>
<view class="wx-cropper-point point-lt" data-drag="leftTop"></view>
</view>
</view>
</view>
<!-- <view class="wx-cropper-drag-box"></view> -->
</view>
<canvas canvas-id="myCanvas" style="position:absolute;border: 1px solid red; {{imageW}}rpx;height:{{imageH}}rpx;top:-9999px;left:-9999px;"></canvas>
<button type="primary" bindtap="getImageInfo" style="position:fixed;bottom:120rpx;90%;left:50%;transform:translate3d(-50%,0,0)"> 确认提交 </button>
</view>
</view>
// pages/wx-cropper/index.js
// 手机的宽度
var windowWRPX = 750
// 拖动时候的 pageX
var pageX = 0
// 拖动时候的 pageY
var pageY = 0
var pixelRatio = wx.getSystemInfoSync().pixelRatio
// 调整大小时候的 pageX
var sizeConfPageX = 0
// 调整大小时候的 pageY
var sizeConfPageY = 0
var initDragCutW = 0
var initDragCutL = 0
var initDragCutH = 0
var initDragCutT = 0
// 移动时 手势位移与 实际元素位移的比
var dragScaleP = 2
Page({
/**
* 页面的初始数据
*/
data: {
imageNum:'', //上传的图片id
headImg:'', //头像上传
ewmImg:'', //二维码上传
imageFixed:false, //裁剪浮层
// imageSrc: 'http://topmdrt-static.oss-cn-shenzhen.aliyuncs.com/images/testimg2.jpeg',
imageSrc: '', //要裁剪的图片
returnImage: '',
isShowImg: false,
// 初始化的宽高
cropperInitW: windowWRPX,
cropperInitH: windowWRPX,
// 动态的宽高
cropperW: windowWRPX,
cropperH: windowWRPX,
// 动态的left top值
cropperL: 0,
cropperT: 0,
// 图片缩放值
scaleP: 0,
imageW: 0,
imageH: 0,
// 裁剪框 宽高
cutW: 400,
cutH: 400,
cutL: 0,
cutT: 0,
},
/**
* 生命周期函数--监听页面加载
*/
onReady: function (options) {
},
/**
* 生命周期函数--监听页面初次渲染完成
*/
onLoad: function () {
var _this = this
// wx.showLoading({
// title: '图片加载中...',
// })
wx.getImageInfo({
src: _this.data.imageSrc,
success: function success(res) {
var innerAspectRadio = res.width / res.height;
console.log(innerAspectRadio)
// 根据图片的宽高显示不同的效果 保证图片可以正常显示
if (innerAspectRadio >= 1) {
_this.setData({
cropperW: windowWRPX,
cropperH: windowWRPX / innerAspectRadio,
// 初始化left right
cropperL: Math.ceil((windowWRPX - windowWRPX) / 2),
cropperT: Math.ceil((windowWRPX - windowWRPX / innerAspectRadio) / 2),
// 裁剪框 宽高
// cutW: windowWRPX - 200,
// cutH: windowWRPX / innerAspectRadio - 200,
cutL: Math.ceil((windowWRPX - windowWRPX + 340) / 2),
cutT: Math.ceil((windowWRPX / innerAspectRadio - (windowWRPX / innerAspectRadio - 20)) / 2),
// 图片缩放值
scaleP: res.width * pixelRatio / windowWRPX,
// 图片原始宽度 rpx
imageW: res.width * pixelRatio,
imageH: res.height * pixelRatio
})
} else {
_this.setData({
cropperW: windowWRPX * innerAspectRadio,
cropperH: windowWRPX,
// 初始化left right
cropperL: Math.ceil((windowWRPX - windowWRPX * innerAspectRadio) / 2),
cropperT: Math.ceil((windowWRPX - windowWRPX) / 2),
// 裁剪框的宽高
// cutW: windowWRPX * innerAspectRadio - 66,
// cutH: 400,
cutL: Math.ceil((windowWRPX * innerAspectRadio - (windowWRPX * innerAspectRadio - 20)) / 2),
cutT: Math.ceil((windowWRPX - 340) / 2),
// 图片缩放值
scaleP: res.width * pixelRatio / windowWRPX,
// 图片原始宽度 rpx
imageW: res.width * pixelRatio,
imageH: res.height * pixelRatio
})
}
_this.setData({
isShowImg: true
})
wx.hideLoading()
}
})
},
// 拖动时候触发的touchStart事件
contentStartMove (e) {
pageX = e.touches[0].pageX
pageY = e.touches[0].pageY
},
// 拖动时候触发的touchMove事件
contentMoveing (e) {
var _this = this
// _this.data.cutL + (e.touches[0].pageX - pageX)
// console.log(e.touches[0].pageX)
// console.log(e.touches[0].pageX - pageX)
var dragLengthX = (pageX - e.touches[0].pageX) * dragScaleP
var dragLengthY = (pageY - e.touches[0].pageY) * dragScaleP
var minX = Math.max(_this.data.cutL - (dragLengthX), 0)
var minY = Math.max(_this.data.cutT - (dragLengthY), 0)
var maxX = _this.data.cropperW - _this.data.cutW
var maxY = _this.data.cropperH - _this.data.cutH
this.setData({
cutL: Math.min(maxX, minX),
cutT: Math.min(maxY, minY),
})
console.log(`${maxX} ----- ${minX}`)
pageX = e.touches[0].pageX
pageY = e.touches[0].pageY
},
// 获取图片
getImageInfo () {
var _this = this
console.log('shengcheng:'+_this.data.imageSrc)
wx.showLoading({
title: '图片生成中...',
})
// wx.downloadFile({
// url:_this.data.imageSrc, //仅为示例，并非真实的资源
// success: function (res) {
// 将图片写入画布
const ctx = wx.createCanvasContext('myCanvas')
// ctx.drawImage(res.tempFilePath)
ctx.drawImage(_this.data.imageSrc)
ctx.draw(true, () => {
// 获取画布要裁剪的位置和宽度 均为百分比 * 画布中图片的宽度 保证了在微信小程序中裁剪的图片模糊 位置不对的问题
var canvasW = (_this.data.cutW / _this.data.cropperW) * (_this.data.imageW / pixelRatio)
var canvasH = (_this.data.cutH / _this.data.cropperH) * (_this.data.imageH / pixelRatio)
var canvasL = (_this.data.cutL / _this.data.cropperW) * (_this.data.imageW / pixelRatio)
var canvasT = (_this.data.cutT / _this.data.cropperH) * (_this.data.imageH / pixelRatio)
console.log(`canvasW:${canvasW} --- canvasH: ${canvasH} --- canvasL: ${canvasL} --- canvasT: ${canvasT} -------- _this.data.imageW: ${_this.data.imageW} ------- _this.data.imageH: ${_this.data.imageH} ---- pixelRatio ${pixelRatio}`)
wx.canvasToTempFilePath({
x: canvasL,
y: canvasT,
canvasW,
height: canvasH,
destWidth: canvasW,
destHeight: canvasH,
canvasId: 'myCanvas',
success: function (res) {
wx.hideLoading()
// 成功获得地址的地方
console.log('end:'+res.tempFilePath)
// 判断时上传头像还是二维码
_this.setData({
imageFixed: false,
})
if (_this.data.imageNum == '1') {
_this.setData({
headImg: res.tempFilePath
})
} else if (_this.data.imageNum == '2') {
_this.setData({
ewmImg: res.tempFilePath
})
}
}
})
})
// }
// })
},
// 设置大小的时候触发的touchStart事件
dragStart(e) {
var _this = this
sizeConfPageX = e.touches[0].pageX
sizeConfPageY = e.touches[0].pageY
initDragCutW = _this.data.cutW
initDragCutL = _this.data.cutL
initDragCutT = _this.data.cutT
initDragCutH = _this.data.cutH
},
// 设置大小的时候触发的touchMove事件
dragMove (e) {
var _this = this
var dragType = e.target.dataset.drag
switch (dragType) {
case 'right':
var dragLength = (sizeConfPageX - e.touches[0].pageX) * dragScaleP
if (initDragCutW >= dragLength) {
// 如果 移动小于0 说明是在往下啦 放大裁剪的高度 这样一来 图片的高度 最大 等于 图片的top值加 当前图片的高度 否则就说明超出界限
if (dragLength < 0 && _this.data.cropperW > initDragCutL + _this.data.cutW) {
this.setData({
cutW: initDragCutW - dragLength
})
}
// 如果是移动 大于0 说明在缩小 只需要缩小的距离小于原本裁剪的高度就ok
if (dragLength > 0) {
this.setData({
cutW: initDragCutW - dragLength
})
}
else {
return
}
} else {
return
}
break;
case 'left':
var dragLength = (dragLength = sizeConfPageX - e.touches[0].pageX) * dragScaleP
console.log(dragLength)
if (initDragCutW >= dragLength && initDragCutL > dragLength) {
if (dragLength < 0 && Math.abs(dragLength) >= initDragCutW) return
this.setData({
cutL: initDragCutL - dragLength,
cutW: initDragCutW + dragLength
})
} else {
return;
}
break;
case 'top':
var dragLength = (sizeConfPageY - e.touches[0].pageY) * dragScaleP
if (initDragCutH >= dragLength && initDragCutT > dragLength) {
if (dragLength < 0 && Math.abs(dragLength) >= initDragCutH) return
this.setData({
cutT: initDragCutT - dragLength,
cutH: initDragCutH + dragLength
})
} else {
return;
}
break;
case 'bottom':
var dragLength = (sizeConfPageY - e.touches[0].pageY) * dragScaleP
// console.log(_this.data.cropperH > _this.data.cutT + _this.data.cutH)
console.log(dragLength)
console.log(initDragCutH >= dragLength)
console.log(_this.data.cropperH > initDragCutT + _this.data.cutH)
// 必须是 dragLength 向上缩小的时候必须小于原本的高度
if (initDragCutH >= dragLength) {
// 如果 移动小于0 说明是在往下啦 放大裁剪的高度 这样一来 图片的高度 最大 等于 图片的top值加 当前图片的高度 否则就说明超出界限
if (dragLength < 0 && _this.data.cropperH > initDragCutT + _this.data.cutH) {
this.setData({
cutH: initDragCutH - dragLength
})
}
// 如果是移动 大于0 说明在缩小 只需要缩小的距离小于原本裁剪的高度就ok
if (dragLength > 0) {
this.setData({
cutH: initDragCutH - dragLength
})
}
else{
return
}
} else {
return
}
break;
case 'rightBottom':
var dragLengthX = (sizeConfPageX - e.touches[0].pageX) * dragScaleP
var dragLengthY = (sizeConfPageY - e.touches[0].pageY) * dragScaleP
if (initDragCutH >= dragLengthY && initDragCutW >= dragLengthX) {
// bottom 方向的变化
if ((dragLengthY < 0 && _this.data.cropperH > initDragCutT + _this.data.cutH) || (dragLengthY > 0)) {
this.setData({
cutH: initDragCutH - dragLengthY
})
}
// right 方向的变化
if ((dragLengthX < 0 && _this.data.cropperW > initDragCutL + _this.data.cutW) || (dragLengthX > 0)) {
this.setData({
cutW: initDragCutW - dragLengthX
})
}
else {
return
}
} else {
return
}
break;
default:
break;
}
},
// 图片上传
upLoad: function () {
},
upEwm: function(e){
var _this = this
wx.chooseImage({
count: 1, // 默认9
sizeType: ['original', 'compressed'], // 可以指定是原图还是压缩图，默认二者都有
sourceType: ['album', 'camera'], // 可以指定来源是相册还是相机，默认二者都有
success: function (res) {
// 返回选定照片的本地文件路径列表，tempFilePath可以作为img标签的src属性显示图片
var tempFilePaths = res.tempFilePaths;
// var mode = parseFloat(e.currentTarget.dataset.current);
console.log('shangchuan:' + tempFilePaths)
console.log(e.currentTarget.dataset.which);
_this.setData({
imageFixed: true,
imageSrc: tempFilePaths.join(),
imageNum: e.currentTarget.dataset.which
})
// start
wx.getImageInfo({
src: _this.data.imageSrc,
success: function success(res) {
var innerAspectRadio = res.width / res.height;
console.log('bili'+innerAspectRadio)
// 根据图片的宽高显示不同的效果 保证图片可以正常显示
if (innerAspectRadio == '1') {
console.log('zhengfangxingtu')
_this.setData({
imageFixed: false,
})
// 判断时上传头像还是二维码
if (_this.data.imageNum == '1') {
_this.setData({
headImg: tempFilePaths.join()
})
} else if (_this.data.imageNum == '2') {
_this.setData({
ewmImg: tempFilePaths.join()
})
}
} else if (innerAspectRadio > 1) {
_this.setData({
cropperW: windowWRPX,
cropperH: windowWRPX / innerAspectRadio,
// 初始化left right
cropperL: Math.ceil((windowWRPX - windowWRPX) / 2),
cropperT: Math.ceil((windowWRPX - windowWRPX / innerAspectRadio) / 2),
// 裁剪框 宽高
// cutW: windowWRPX - 200,
// cutH: windowWRPX / innerAspectRadio - 200,
cutL: Math.ceil((windowWRPX - windowWRPX + 340) / 2),
cutT: Math.ceil((windowWRPX / innerAspectRadio - (windowWRPX / innerAspectRadio - 20)) / 2),
// 图片缩放值
scaleP: res.width * pixelRatio / windowWRPX,
// 图片原始宽度 rpx
imageW: res.width * pixelRatio,
imageH: res.height * pixelRatio
})
} else {
_this.setData({
cropperW: windowWRPX * innerAspectRadio,
cropperH: windowWRPX,
// 初始化left right
cropperL: Math.ceil((windowWRPX - windowWRPX * innerAspectRadio) / 2),
cropperT: Math.ceil((windowWRPX - windowWRPX) / 2),
// 裁剪框的宽高
// cutW: windowWRPX * innerAspectRadio - 66,
// cutH: 400,
cutL: Math.ceil((windowWRPX * innerAspectRadio - (windowWRPX * innerAspectRadio - 20)) / 2),
cutT: Math.ceil((windowWRPX - 340) / 2),
// 图片缩放值
scaleP: res.width * pixelRatio / windowWRPX,
// 图片原始宽度 rpx
imageW: res.width * pixelRatio,
imageH: res.height * pixelRatio
})
}
_this.setData({
isShowImg: true
})
wx.hideLoading()
}
})
// end
}
})
},
/**
* 生命周期函数--监听页面显示
*/
onShow: function () {
},
/**
* 生命周期函数--监听页面隐藏
*/
onHide: function () {
},
/**
* 生命周期函数--监听页面卸载
*/
onUnload: function () {
},
/**
* 页面相关事件处理函数--监听用户下拉动作
*/
onPullDownRefresh: function () {
},
/**
* 页面上拉触底事件的处理函数
*/
onReachBottom: function () {
},
/**
* 用户点击右上角分享
*/
onShareAppMessage: function () {
}
})
/* pages/wx-cropper/index.wxss */
.fixed-upimg{
position: fixed;
top: 0;
left: 0;
right: 0;
bottom: 0;
background-color: #fff;
}
.wx-content-info{
position: fixed;
top: 130rpx;
left: 0;
right: 0;
bottom: 0;
}
.wx-corpper{
position: relative;
overflow: hidden;
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
-webkit-tap-highlight-color: transparent;
-webkit-touch-callout: none;
box-sizing: border-box;
}
.wx-corpper-content{
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
}
.wx-corpper-content image {
display: block;
100%;
min- 0 !important;
max- none !important;
height: 100%;
min-height: 0 !important;
max-height: none !important;
image-orientation: 0deg !important;
margin: 0 auto;
}
/* 移动图片效果 */
.wx-cropper-drag-box{
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
cursor: move;
background: rgba(0,0,0,0.6);
z-index: 1;
}
/* 内部的信息 */
.wx-corpper-crop-box{
position: absolute;
500rpx;
height: 500rpx;
background: rgba(255,255,255,0.3);
z-index: 2;
}
.wx-corpper-crop-box .wx-cropper-view-box {
position: relative;
display: block;
100%;
height: 100%;
overflow: visible;
outline: 1px solid #69f;
outline-color: rgba(102, 153, 255, .75)
}
/* 横向虚线 */
.wx-cropper-dashed-h{
position: absolute;
top: 33.33333333%;
left: 0;
100%;
height: 33.33333333%;
border-top: 1px dashed rgba(255,255,255,0.5);
border-bottom: 1px dashed rgba(255,255,255,0.5);
}
/* 纵向虚线 */
.wx-cropper-dashed-v{
position: absolute;
left: 33.33333333%;
top: 0;
33.33333333%;
height: 100%;
border-left: 1px dashed rgba(255,255,255,0.5);
border-right: 1px dashed rgba(255,255,255,0.5);
}
/* 四个方向的线 为了之后的拖动事件*/
.wx-cropper-line-t{
position: absolute;
display: block;
100%;
background-color: #69f;
top: 0;
left: 0;
height: 1px;
opacity: 0.1;
cursor: n-resize;
}
.wx-cropper-line-t::before{
content: '';
position: absolute;
top: 50%;
right: 0rpx;
100%;
-webkit-transform: translate3d(0,-50%,0);
transform: translate3d(0,-50%,0);
bottom: 0;
height: 41rpx;
background: transparent;
z-index: 11;
}
.wx-cropper-line-r{
position: absolute;
display: block;
background-color: #69f;
top: 0;
right: 0px;
1px;
opacity: 0.1;
height: 100%;
cursor: e-resize;
}
.wx-cropper-line-r::before{
content: '';
position: absolute;
top: 0;
left: 50%;
41rpx;
-webkit-transform: translate3d(-50%,0,0);
transform: translate3d(-50%,0,0);
bottom: 0;
height: 100%;
background: transparent;
z-index: 11;
}
.wx-cropper-line-b{
position: absolute;
display: block;
100%;
background-color: #69f;
bottom: 0;
left: 0;
height: 1px;
opacity: 0.1;
cursor: s-resize;
}
.wx-cropper-line-b::before{
content: '';
position: absolute;
top: 50%;
right: 0rpx;
100%;
-webkit-transform: translate3d(0,-50%,0);
transform: translate3d(0,-50%,0);
bottom: 0;
height: 41rpx;
background: transparent;
z-index: 11;
}
.wx-cropper-line-l{
position: absolute;
display: block;
background-color: #69f;
top: 0;
left: 0;
1px;
opacity: 0.1;
height: 100%;
cursor: w-resize;
}
.wx-cropper-line-l::before{
content: '';
position: absolute;
top: 0;
left: 50%;
41rpx;
-webkit-transform: translate3d(-50%,0,0);
transform: translate3d(-50%,0,0);
bottom: 0;
height: 100%;
background: transparent;
z-index: 11;
}
.wx-cropper-point{
5px;
height: 5px;
background-color: #69f;
opacity: .75;
position: absolute;
z-index: 3;
}
.point-t{
top: -3px;
left: 50%;
margin-left: -3px;
cursor: n-resize;
}
.point-tr{
top: -3px;
left: 100%;
margin-left: -3px;
cursor: n-resize;
}
.point-r{
top: 50%;
left:100%;
margin-left: -3px;
margin-top: -3px;
cursor: n-resize;
}
.point-rb{
left: 100%;
top: 100%;
-webkit-transform: translate3d(-50%,-50%,0);
transform: translate3d(-50%,-50%,0);
cursor: n-resize;
24rpx;
height: 24rpx;
background-color: #69f;
position: absolute;
z-index: 1112;
opacity: 1;
}
.point-b{
left:50%;
top: 100%;
margin-left: -3px;
margin-top: -3px;
cursor: n-resize;
}
.point-bl{
left:0%;
top: 100%;
margin-left: -3px;
margin-top: -3px;
cursor: n-resize;
}
.point-l{
left:0%;
top: 50%;
margin-left: -3px;
margin-top: -3px;
cursor: n-resize;
}
.point-lt{
left:0%;
top: 0%;
margin-left: -3px;
margin-top: -3px;
cursor: n-resize;
}
/* 裁剪框预览内容 */
.wx-cropper-viewer{
position: relative;
100%;
height: 100%;
overflow: hidden;
}
.wx-cropper-viewer image{
position: absolute;
z-index: 2;
}