微信小程序图片选择区域裁剪实现方法

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

开始裁剪

点击上传图片

点击确认

等屏裁剪

区域裁剪

重新裁剪

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;

coRcqGuxONUlor: #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'
　　//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.http://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,

RcqGuxONU 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RcqGuxONU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

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