如何实现微信小程序图片选择区域裁剪

  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      

.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; }

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 }) } }) },

// 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 }) } }) },

// 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() },

//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 }) },

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 }) },

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 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() },