微信小程序图片选择区域裁剪实现方法

本文介绍了微信小程序图片选择区域屏裁剪实现方法，分享给大家。具体如下：

效果图

HTML代码

<view class="index_all_box">
<view class="imgCut_header">
<view class="imgCut_header_l" bindtap='okCutImg'>开始裁剪</view>
<view class="imgCut_header_m" bindtap='clickUpImg'>点击上传图片</view>
<view class="imgCut_header_r" bindtap='okBtn'>点击确认</view>
</view>
<!-- 选择裁剪模式 -->
<view class="selectCutMode" wx:if='{{alreay}}'>
<view class="selectCutMode_in {{cutType?'selectCutMode_in_act':''}}" bindtap='etcType'>
等屏裁剪
</view>
<view class="selectCutMode_in {{!cutType?'selectCutMode_in_act':''}}" bindtap='areaType'>
区域裁剪
</view>
</view>
<view class="areaSelct_box" wx:if='{{!cutType && alreay}}'>
<slider bindchange="areaChange" min="50" max="100" show-value value='{{propor}}'/>
</view>
<view class="cutImg_box" wx:if='{{!prienFlag}}'>
<view class="cutImg_box_t">
<image src="{{cutImgUrl}}" mode='widthFix'></image>
</view>
<view class="clickCutImg_txt" bindtap='againBtn'>重新裁剪</view>
</view>
<view class="allCavans" wx:if='{{prienFlag}}' style='width: {{canvasW}}px;height: {{canvasH}}px' >
<canvas class='canvasSty' style='width: {{canvasW}}px;height: {{canvasH}}px' canvas-id='cutImg' disable-scroll='true' bindtouchmove='canvasMove'></canvas>
<view class="allCavans_inbg" style='width: {{canvasW}}px;height:{{canvasH}}px; background: url({{img}});background-size: 100% 100%'></view>
</view>
</view>

CSS代码

.imgCut_header{
padding: 30rpx;
display: flex;
justify-content: space-between;
align-items: center;
background: #000;
color: #fff;
font-size: 24rpx;
}
.allCavans{
margin: 20rpx auto;
position: relative;
}
.canvasSty{
position: absolute;
}
.cutImg_box{
width: 100%;
border-bottom: 2rpx #f98700 solid;
padding-bottom: 20rpx;
}
.cutImg_box .cutImg_box_t{
width: 90%;
margin: 20rpx auto;
}
.cutImg_box image{
width: 100%;
}
.cutImg_box .cutImg_box_b{
margin-top: 20rpx;
width: 80%;
height: 80rpx;
line-height: 80rpx;
background: #f98700;
color: #fff;
border-radius: 10rpx;
text-align: center;
margin:0rpx auto;
}
.selectCutMode{
background: #fff;
display: flex;
justify-content: space-between;
align-items: center;
}
.selectCutMode .selectCutMode_in{
width: 100%;
text-align: center;
background: #fff;
color: #f98700;
font-size: 24rpx;
padding: 20rpx;
}
.selectCutMode .selectCutMode_in_act{
background: #f98700;
color: #fff;
padding: 20rpx;
}
.areaSelct_box{
width: 100%;
display: flex;
align-items: center;
height: 50rpx;
justify-content: center;
margin-top: 20rpx;
}
.areaSelct_box slider{
width: 80%;
}
.cutImg_box .clickCutImg_txt{
width: 100%;
text-align: center;
height: 50rpx;
font-size: 24rpx;
line-height: 50rpx;
color: #999;
}

JS代码部分

初始加载带入上一个页面带过来的参数路径

onLoad: function (options) {
var that = this;
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
var aa = 'https://pintuanqu.oss-cn-hangzhou.aliyuncs.com/Uploads/Picture/goodsShow/20171201/5a2125fc86566.png'<br />　　//获取当前屏幕宽度
var phoneW = Number(util.nowPhoneWH()[0]*90)/100;
var cutH = 150;
wx.getImageInfo({
src: aa,
success: function (res) {
var w = phoneW;
var h = (phoneW/Number(res.width))*Number(res.height)
ctx.save()
ctx.drawImage(aa, 0, 0, w, h)
ctx.restore()
ctx.setFillStyle('red')
ctx.fillRect(0, 0, phoneW, cutH)
ctx.draw()
that.setData({
canvasW:w,
canvasH:h,
img:aa,
cutH:cutH
})
}
})
},

确定选择区域开始裁剪

// 点击确认裁剪图片
okCutImg:function(){
var that = this;
var canvasW = that.data.canvasW;
var canvasH = that.data.canvasH;
var nowCutW = that.data.cutType?canvasW:that.data.nowCutW;
var nowCutH = that.data.cutType?that.data.cutH:that.data.nowCutH;
var cutX = that.data.cutX;
var cutY = that.data.cutY;
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(1)
ctx.drawImage(that.data.img, 0, 0, canvasW, canvasH)
ctx.draw()
wx.canvasToTempFilePath({
x: cutX,
y: cutY,
width: nowCutW,
height: nowCutH,
destWidth: nowCutW,
destHeight: nowCutH,
canvasId: 'cutImg',
success: function(res) {
var aa = res.tempFilePath
that.setData({
cutImgUrl:aa,
prienFlag:false,
alreay:false
})
}
})
},

红框根据手指移动方法

// 点击红框开始移动
canvasMove:function(e){
var that = this;
var canvasW = that.data.canvasW;
var canvasH = that.data.canvasH;
var nowCutW = that.data.cutType?canvasW:that.data.nowCutW;
var nowCutH = that.data.cutType?that.data.cutH:that.data.nowCutH
var touches = e.touches[0];
var x = touches.x;
var y = touches.y-(Number(nowCutH)/2);
that.data.cutType?x=0:x=x-(Number(nowCutW)/2);
that.setData({
cutX:x,
cutY:y
})
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
ctx.drawImage(that.data.img, 0, 0, canvasW, canvasH)
ctx.setFillStyle('red')
ctx.fillRect(x, y, nowCutW, nowCutH)
ctx.draw()
},

上方两个选择裁剪方式的按钮

等屏裁剪

//等屏裁剪
etcType:function(){
var that = this;
var propor = 100;
var canvasW = that.data.canvasW;
var canvasH = that.data.canvasH;
var cutH = that.data.cutH;
var nowCutW = (Number(canvasW)*propor)/100
var nowCutH = (Number(cutH)*propor)/100
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
ctx.drawImage(that.data.img, 0, 0, canvasW, canvasH)
ctx.setFillStyle('red')
ctx.fillRect(0, 0, nowCutW, nowCutH)
ctx.draw()
that.setData({
nowCutW:nowCutW,
nowCutH:nowCutH,
cutType:true
})
},

局域裁剪

areaType:function(){
var that = this;
var propor = that.data.propor;
var canvasW = that.data.canvasW;
var canvasH = that.data.canvasH;
var cutH = that.data.cutH;
var nowCutW = (Number(canvasW)*propor)/100
var nowCutH = (Number(cutH)*propor)/100
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
ctx.drawImage(that.data.img, 0, 0, canvasW, canvasH)
ctx.setFillStyle('red')
ctx.fillRect(0,0, nowCutW, nowCutH)
ctx.draw()
that.setData({
nowCutW:nowCutW,
nowCutH:nowCutH,
cutType:false
})
},

局域裁剪上方的滑动选择红框根据宽度等比例缩放

areaChange:function(e){
var that = this;
var propor = e.detail.value;
var canvasW = that.data.canvasW;
var canvasH = that.data.canvasH;
var cutH = that.data.cutH;
var nowCutW = (Number(canvasW)*propor)/100
var nowCutH = (Number(cutH)*propor)/100
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
ctx.drawImage(that.data.img, 0, 0, canvasW, canvasH)
ctx.setFillStyle('red')
ctx.fillRect(that.data.cutX||0, that.data.cutY||0,nowCutW, nowCutH)
ctx.draw()
that.setData({
nowCutW:nowCutW,
nowCutH:nowCutH,
propor:propor
})
},

重新裁剪回到初始选择图片的页面

// 重新裁剪
againBtn:function(){
var that = this;
var data = that.data
this.setData({
prienFlag:true,
alreay:true
})
const ctx = wx.createCanvasContext('cutImg');
ctx.setGlobalAlpha(0.4)
ctx.drawImage(data.img, 0, 0, data.canvasW, data.canvasH)
ctx.setFillStyle('red')
ctx.fillRect(that.data.cutX||0, that.data.cutY||0, data.nowCutW||data.canvasW, data.nowCutH||data.cutH)
ctx.draw()
},

现在IOS还有个坑就是裁剪不了,官方正在修复不知道什么时候好

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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