uni-app 对上传的图片进行裁剪
<template>
<view class="container">
<view class="page-body uni-content-info">
<view class='cropper-content'>
<view v-if="isShowImg" class="uni-corpper" :style="'width:'+cropperInitW+'px;height:'+cropperInitH+'px;background:#000'">
<view class="uni-corpper-content" :style="'width:'+cropperW+'px;height:'+cropperH+'px;left:'+cropperL+'px;top:'+cropperT+'px'">
<image :src="imageSrc" :style="'width:'+cropperW+'px;height:'+cropperH+'px'"></image>
<view class="uni-corpper-crop-box" @touchstart.stop="contentStartMove" @touchmove.stop="contentMoveing" @touchend.stop="contentTouchEnd"
:style="'left:'+cutL+'px;top:'+cutT+'px;right:'+cutR+'px;bottom:'+cutB+'px'">
<view class="uni-cropper-view-box">
<view class="uni-cropper-dashed-h"></view>
<view class="uni-cropper-dashed-v"></view>
<view class="uni-cropper-line-t" data-drag="top" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-line-r" data-drag="right" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-line-b" data-drag="bottom" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-line-l" data-drag="left" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-point point-t" data-drag="top" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-point point-tr" data-drag="topTight"></view>
<view class="uni-cropper-point point-r" data-drag="right" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-point point-rb" data-drag="rightBottom" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-point point-b" data-drag="bottom" @touchstart.stop="dragStart" @touchmove.stop="dragMove" @touchend.stop="dragEnd"></view>
<view class="uni-cropper-point point-bl" data-drag="bottomLeft"></view>
<view class="uni-cropper-point point-l" data-drag="left" @touchstart.stop="dragStart" @touchmove.stop="dragMove"></view>
<view class="uni-cropper-point point-lt" data-drag="leftTop"></view>
</view>
</view>
</view>
</view>
</view>
<view class='cropper-config'>
<button type="primary reverse" @click="getImage" style='margin-top: 30upx;'> 选择图片 </button>
<button type="warn" @click="getImageInfo" style='margin-top: 30upx;'> 点击生成图片 </button>
</view>
<canvas canvas-id="myCanvas" :style="'position:absolute;border: 1px solid red; width:'+imageW+'px;height:'+imageH+'px;top:-9999px;left:-9999px;'"></canvas>
</view>
<page-foot :name="name"></page-foot>
</view>
</template>
<script>
let sysInfo = uni.getSystemInfoSync();
let SCREEN_WIDTH = sysInfo.screenWidth
let PAGE_X, // 手按下的x位置
PAGE_Y, // 手按下y的位置
PR = sysInfo.pixelRatio, // dpi
T_PAGE_X, // 手移动的时候x的位置
T_PAGE_Y, // 手移动的时候Y的位置
CUT_L, // 初始化拖拽元素的left值
CUT_T, // 初始化拖拽元素的top值
CUT_R, // 初始化拖拽元素的
CUT_B, // 初始化拖拽元素的
CUT_W, // 初始化拖拽元素的宽度
CUT_H, // 初始化拖拽元素的高度
IMG_RATIO, // 图片比例
IMG_REAL_W, // 图片实际的宽度
IMG_REAL_H, // 图片实际的高度
DRAFG_MOVE_RATIO = 1, //移动时候的比例,
INIT_DRAG_POSITION = 100, // 初始化屏幕宽度和裁剪区域的宽度之差，用于设置初始化裁剪的宽度
DRAW_IMAGE_W = sysInfo.screenWidth // 设置生成的图片宽度
export default {
/**
* 页面的初始数据
*/
data() {
return {
name:'杨大宝',
imageSrc: 'https://img-cdn-qiniu.dcloud.net.cn/demo_crop.jpg',
isShowImg: false,
// 初始化的宽高
cropperInitW: SCREEN_WIDTH,
cropperInitH: SCREEN_WIDTH,
// 动态的宽高
cropperW: SCREEN_WIDTH,
cropperH: SCREEN_WIDTH,
// 动态的left top值
cropperL: 0,
cropperT: 0,
transL: 0,
transT: 0,
// 图片缩放值
scaleP: 0,
imageW: 0,
imageH: 0,
// 裁剪框 宽高
cutL: 0,
cutT: 0,
cutB: SCREEN_WIDTH,
cutR: '100%',
qualityWidth: DRAW_IMAGE_W,
innerAspectRadio: DRAFG_MOVE_RATIO
}
},
/**
* 生命周期函数--监听页面加载
*/
onLoad: function (options) {},
/**
* 生命周期函数--监听页面初次渲染完成
*/
onReady: function () {
this.loadImage();
},
methods: {
setData: function (obj) {
let that = this;
Object.keys(obj).forEach(function (key) {
that.$set(that.$data, key, obj[key])
});
},
getImage: function () {
var _this = this
uni.chooseImage({
success: function (res) {
_this.setData({
imageSrc: res.tempFilePaths[0],
})
_this.loadImage();
},
})
},
loadImage: function () {
var _this = this
uni.showLoading({
title: '图片加载中...',
})
uni.getImageInfo({
src: _this.imageSrc,
success: function success(res) {
IMG_RATIO = res.width / res.height
if (IMG_RATIO >= 1) {
IMG_REAL_W = SCREEN_WIDTH
IMG_REAL_H = SCREEN_WIDTH / IMG_RATIO
} else {
IMG_REAL_W = SCREEN_WIDTH * IMG_RATIO
IMG_REAL_H = SCREEN_WIDTH
}
let minRange = IMG_REAL_W > IMG_REAL_H ? IMG_REAL_W : IMG_REAL_H
INIT_DRAG_POSITION = minRange > INIT_DRAG_POSITION ? INIT_DRAG_POSITION : minRange
// 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 (IMG_RATIO >= 1) {
let cutT = Math.ceil((SCREEN_WIDTH / IMG_RATIO - (SCREEN_WIDTH / IMG_RATIO - INIT_DRAG_POSITION)) / 2);
let cutB = cutT;
let cutL = Math.ceil((SCREEN_WIDTH - SCREEN_WIDTH + INIT_DRAG_POSITION) / 2);
let cutR = cutL;
_this.setData({
cropperW: SCREEN_WIDTH,
cropperH: SCREEN_WIDTH / IMG_RATIO,
// 初始化left right
cropperL: Math.ceil((SCREEN_WIDTH - SCREEN_WIDTH) / 2),
cropperT: Math.ceil((SCREEN_WIDTH - SCREEN_WIDTH / IMG_RATIO) / 2),
cutL: cutL,
cutT: cutT,
cutR: cutR,
cutB: cutB,
// 图片缩放值
imageW: IMG_REAL_W,
imageH: IMG_REAL_H,
scaleP: IMG_REAL_W / SCREEN_WIDTH,
qualityWidth: DRAW_IMAGE_W,
innerAspectRadio: IMG_RATIO
})
} else {
let cutL = Math.ceil((SCREEN_WIDTH * IMG_RATIO - (SCREEN_WIDTH * IMG_RATIO)) / 2);
let cutR = cutL;
let cutT = Math.ceil((SCREEN_WIDTH - INIT_DRAG_POSITION) / 2);
let cutB = cutT;
_this.setData({
cropperW: SCREEN_WIDTH * IMG_RATIO,
cropperH: SCREEN_WIDTH,
// 初始化left right
cropperL: Math.ceil((SCREEN_WIDTH - SCREEN_WIDTH * IMG_RATIO) / 2),
cropperT: Math.ceil((SCREEN_WIDTH - SCREEN_WIDTH) / 2),
cutL: cutL,
cutT: cutT,
cutR: cutR,
cutB: cutB,
// 图片缩放值
imageW: IMG_REAL_W,
imageH: IMG_REAL_H,
scaleP: IMG_REAL_W / SCREEN_WIDTH,
qualityWidth: DRAW_IMAGE_W,
innerAspectRadio: IMG_RATIO
})
}
_this.setData({
isShowImg: true
})
uni.hideLoading()
}
})
},
// 拖动时候触发的touchStart事件
contentStartMove(e) {
PAGE_X = e.touches[0].pageX
PAGE_Y = e.touches[0].pageY
},
// 拖动时候触发的touchMove事件
contentMoveing(e) {
var _this = this
var dragLengthX = (PAGE_X - e.touches[0].pageX) * DRAFG_MOVE_RATIO
var dragLengthY = (PAGE_Y - e.touches[0].pageY) * DRAFG_MOVE_RATIO
// 左移
if (dragLengthX > 0) {
if (this.cutL - dragLengthX < 0) dragLengthX = this.cutL
} else {
if (this.cutR + dragLengthX < 0) dragLengthX = -this.cutR
}
if (dragLengthY > 0) {
if (this.cutT - dragLengthY < 0) dragLengthY = this.cutT
} else {
if (this.cutB + dragLengthY < 0) dragLengthY = -this.cutB
}
this.setData({
cutL: this.cutL - dragLengthX,
cutT: this.cutT - dragLengthY,
cutR: this.cutR + dragLengthX,
cutB: this.cutB + dragLengthY
})
PAGE_X = e.touches[0].pageX
PAGE_Y = e.touches[0].pageY
},
contentTouchEnd() {
},
// 获取图片
getImageInfo() {
var _this = this;
uni.showLoading({
title: '图片生成中...',
});
// 将图片写入画布
const ctx = uni.createCanvasContext('myCanvas');
ctx.drawImage(_this.imageSrc, 0, 0, IMG_REAL_W, IMG_REAL_H);
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 canvasT = (_this.cutT / _this.cropperH) * (_this.imageH / pixelRatio)
var canvasW = ((_this.cropperW - _this.cutL - _this.cutR) / _this.cropperW) * IMG_REAL_W;
var canvasH = ((_this.cropperH - _this.cutT - _this.cutB) / _this.cropperH) * IMG_REAL_H;
var canvasL = (_this.cutL / _this.cropperW) * IMG_REAL_W;
var canvasT = (_this.cutT / _this.cropperH) * IMG_REAL_H;
uni.canvasToTempFilePath({
x: canvasL,
y: canvasT,
width: canvasW,
height: canvasH,
destWidth: canvasW,
destHeight: canvasH,
quality: 0.5,
canvasId: 'myCanvas',
success: function (res) {
uni.hideLoading()
// 成功获得地址的地方
uni.previewImage({
current: '', // 当前显示图片的http链接
urls: [res.tempFilePath] // 需要预览的图片http链接列表
})
}
});
});
},
// 设置大小的时候触发的touchStart事件
dragStart(e) {
T_PAGE_X = e.touches[0].pageX
T_PAGE_Y = e.touches[0].pageY
CUT_L = this.cutL
CUT_R = this.cutR
CUT_B = this.cutB
CUT_T = this.cutT
},
// 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 = (T_PAGE_X - e.touches[0].pageX) * DRAFG_MOVE_RATIO
if (CUT_R + dragLength < 0) dragLength = -CUT_R
this.setData({
cutR: CUT_R + dragLength
})
break;
case 'left':
var dragLength = (T_PAGE_X - e.touches[0].pageX) * DRAFG_MOVE_RATIO
if (CUT_L - dragLength < 0) dragLength = CUT_L
if ((CUT_L - dragLength) > (this.cropperW - this.cutR)) dragLength = CUT_L - (this.cropperW - this.cutR)
this.setData({
cutL: CUT_L - dragLength
})
break;
case 'top':
var dragLength = (T_PAGE_Y - e.touches[0].pageY) * DRAFG_MOVE_RATIO
if (CUT_T - dragLength < 0) dragLength = CUT_T
if ((CUT_T - dragLength) > (this.cropperH - this.cutB)) dragLength = CUT_T - (this.cropperH - this.cutB)
this.setData({
cutT: CUT_T - dragLength
})
break;
case 'bottom':
var dragLength = (T_PAGE_Y - e.touches[0].pageY) * DRAFG_MOVE_RATIO
if (CUT_B + dragLength < 0) dragLength = -CUT_B
this.setData({
cutB: CUT_B + dragLength
})
break;
case 'rightBottom':
var dragLengthX = (T_PAGE_X - e.touches[0].pageX) * DRAFG_MOVE_RATIO
var dragLengthY = (T_PAGE_Y - e.touches[0].pageY) * DRAFG_MOVE_RATIO
if (CUT_B + dragLengthY < 0) dragLengthY = -CUT_B
if (CUT_R + dragLengthX < 0) dragLengthX = -CUT_R
let cutB = CUT_B + dragLengthY;
let cutR = CUT_R + dragLengthX;
this.setData({
cutB: cutB,
cutR: cutR
})
break;
default:
break;
}
}
}
}
</script>
<style>
/* pages/uni-cropper/index.wxss */
.uni-content-info {
/* position: fixed;
top: 0;
left: 0;
right: 0;
bottom: 0;
display: block;
align-items: center;
flex-direction: column; */
}
.cropper-config {
padding: 20upx 40upx;
}
.cropper-content {
min-height: 750upx;
width: 100%;
}
.uni-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;
}
.uni-corpper-content {
position: relative;
}
.uni-corpper-content image {
display: block;
width: 100%;
min-width: 0 !important;
max-width: 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 */
.uni-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 */
.uni-corpper-crop-box {
position: absolute;
background: rgba(255, 255, 255, 0.3);
z-index: 2;
}
.uni-corpper-crop-box .uni-cropper-view-box {
position: relative;
display: block;
width: 100%;
height: 100%;
overflow: visible;
outline: 1upx solid #69f;
outline-color: rgba(102, 153, 255, .75)
}
/* 横向虚线 */
.uni-cropper-dashed-h {
position: absolute;
top: 33.33333333%;
left: 0;
width: 100%;
height: 33.33333333%;
border-top: 1upx dashed rgba(255, 255, 255, 0.5);
border-bottom: 1upx dashed rgba(255, 255, 255, 0.5);
}
/* 纵向虚线 */
.uni-cropper-dashed-v {
position: absolute;
left: 33.33333333%;
top: 0;
width: 33.33333333%;
height: 100%;
border-left: 1upx dashed rgba(255, 255, 255, 0.5);
border-right: 1upx dashed rgba(255, 255, 255, 0.5);
}
/* 四个方向的线 为了之后的拖动事件*/
.uni-cropper-line-t {
position: absolute;
display: block;
width: 100%;
top: 0;
left: 0;
height: 1upx;
opacity: 0.1;
cursor: n-resize;
}
.uni-cropper-line-t::before {
content: '';
position: absolute;
top: 50%;
right: 0upx;
width: 100%;
-webkit-transform: translate3d(0, -50%, 0);
transform: translate3d(0, -50%, 0);
bottom: 0;
height: 41upx;
background: transparent;
z-index: 11;
}
.uni-cropper-line-r {
position: absolute;
display: block;
top: 0;
right: 0upx;
width: 1upx;
opacity: 0.1;
height: 100%;
cursor: e-resize;
}
.uni-cropper-line-r::before {
content: '';
position: absolute;
top: 0;
left: 50%;
width: 41upx;
-webkit-transform: translate3d(-50%, 0, 0);
transform: translate3d(-50%, 0, 0);
bottom: 0;
height: 100%;
background: transparent;
z-index: 11;
}
.uni-cropper-line-b {
position: absolute;
display: block;
width: 100%;
bottom: 0;
left: 0;
height: 1upx;
opacity: 0.1;
cursor: s-resize;
}
.uni-cropper-line-b::before {
content: '';
position: absolute;
top: 50%;
right: 0upx;
width: 100%;
-webkit-transform: translate3d(0, -50%, 0);
transform: translate3d(0, -50%, 0);
bottom: 0;
height: 41upx;
background: transparent;
z-index: 11;
}
.uni-cropper-line-l {
position: absolute;
display: block;
top: 0;
left: 0;
width: 1upx;
opacity: 0.1;
height: 100%;
cursor: w-resize;
}
.uni-cropper-line-l::before {
content: '';
position: absolute;
top: 0;
left: 50%;
width: 41upx;
-webkit-transform: translate3d(-50%, 0, 0);
transform: translate3d(-50%, 0, 0);
bottom: 0;
height: 100%;
background: transparent;
z-index: 11;
}
.uni-cropper-point {
width: 5upx;
height: 5upx;
opacity: .75;
position: absolute;
z-index: 3;
}
.point-t {
top: -3upx;
left: 50%;
margin-left: -3upx;
cursor: n-resize;
}
.point-tr {
top: -3upx;
left: 100%;
margin-left: -3upx;
cursor: n-resize;
}
.point-r {
top: 50%;
left: 100%;
margin-left: -3upx;
margin-top: -3upx;
cursor: n-resize;
}
.point-rb {
left: 100%;
top: 100%;
-webkit-transform: translate3d(-50%, -50%, 0);
transform: translate3d(-50%, -50%, 0);
cursor: n-resize;
width: 36upx;
height: 36upx;
position: absolute;
z-index: 1112;
opacity: 1;
}
.point-b {
left: 50%;
top: 100%;
margin-left: -3upx;
margin-top: -3upx;
cursor: n-resize;
}
.point-bl {
left: 0%;
top: 100%;
margin-left: -3upx;
margin-top: -3upx;
cursor: n-resize;
}
.point-l {
left: 0%;
top: 50%;
margin-left: -3upx;
margin-top: -3upx;
cursor: n-resize;
}
.point-lt {
left: 0%;
top: 0%;
margin-left: -3upx;
margin-top: -3upx;
cursor: n-resize;
}
/* 裁剪框预览内容 */
.uni-cropper-viewer {
position: relative;
width: 100%;
height: 100%;
overflow: hidden;
}
.uni-cropper-viewer image {
position: absolute;
z-index: 2;
}
</style>
来源：https://www.cnblogs.com/cfcastiel/articles/14470188.html
