微信小程序如何实现裁剪图片大小

这篇文章主要介绍“微信小程序如何实现裁剪图片大小”，在日常操作中，相信很多人在微信小程序如何实现裁剪图片大小问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”微信小程序如何实现裁剪图片大小”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

效果图

.wxml

<button bindtap="uploadtap">上传图片</button><image  mode="widthFix" src="{{canfile_image}}"></image><canvas canvas-id="myCanvas" id="myCanvas" ></canvas><view class="canvas_model" wx:if="{{canvas_arr.show}}" catchtouchmove="setTouchMove">  <view class="canvas_view"   bindtouchstart="handletouchstart" bindtouchmove="handletouchmove">    <image  src="{{canvas_arr.src}}"></image>    <view >      <view class="canvas_horn" >        <view></view>        <view></view>        <view></view>        <view></view>        <view></view>        <view></view>        <image  src="{{canvas_arr.src}}"></image>      </view>    </view>  </view>  <view class="canvas_bar" wx:if="{{cutting.show}}">    <view bindtap="color_tap">×</view>    <view class="bar_tab {{color_status?'tab_cation':''}}" bindtap="color_tap" data-type="1">      <view>浅色</view>      <view>深色</view>      <view></view>    </view>    <view bindtap="ationimg">√</view>  </view></view>

.wxss

 .canvas_model{width: 100%;height: 100vh;position: fixed;left: 0;top: 0;background: rgba(0, 0, 0, 0.6);z-index: 10;display:flex;justify-content: center;padding-top: 10vh;animation:model 0.3s;}@keyframes model{  from { opacity: 0;transfORM: scale(0.5); }  to { opacity:1;transform: scale(1); }}.canvas_view{float: left;position: relative;}.canvas_view>view{width: 100%;height: 100%;position: absolute;left: 0;top: 0;background: rgba(255, 255, 255, 0.4);transition: all 0.3s;}.canvas_horn{position: absolute;left: 0;width: 100%;overflow: hidden;}.canvas_horn>view{width: 40rpx;height: 40rpx;position: absolute;z-index: 1;}.canvas_horn>image{position: absolute;left: 0;top: 0;}.canvas_horn>view:nth-child(1){border-left: 2px solid #fff;border-top: 2px solid #fff;left: 0;top: 0;}.canvas_horn>view:nth-child(2){border-right: 2px solid #fff;border-top: 2px solid #fff;right: 0;top: 0;}.canvas_horn>view:nth-child(3){border-left: 2px solid #fff;border-bottom:2px solid #fff;left: 0;bottom: 0;}.canvas_horn>view:nth-child(4){border-right: 2px solid #fff;border-bottom: 2px solid #fff;right: 0;bottom: 0;}.canvas_horn>view:nth-child(5){width: 60rpx;height: 2px;background: #fff;top: 0;left: 0;right: 0;margin: 0 auto;}.canvas_horn>view:nth-child(6){width: 60rpx;height: 2px;background: #fff;bottom: 0;left: 0;right: 0;margin: 0 auto;}.canvas_bar{width: 100%;height: 14vh;display: flex;align-items: center;justify-content: space-between;background: #fff;position: absolute;left: 0;bottom: 0;animation:bartion 0.5s;}@keyframes bartion{  from { bottom: -14vh; }  to { bottom: 0; }}.canvas_bar>view:nth-child(1),.canvas_bar>view:nth-child(3){width: 160rpx;height: 100%;display: flex;align-items: center;justify-content: center;font-size: 44rpx;font-weight: 700;}.bar_tab{width: 300rpx;display: flex;height: 60rpx;border-radius: 10rpx;border: 1px solid #f4f4f4;line-height: 60rpx;position: relative;font-size: 24rpx;color: #333;}.bar_tab>view{width: 50%;height: 100%;text-align: center;position: relative;z-index: 1;transition: all 0.3s;}.bar_tab>view:nth-child(1){color: #fff;}.bar_tab>view:nth-child(3){position: absolute;left: 0;top: 0;background: #0081ff;border-radius: 10rpx;z-index: 0;}.tab_cation>view:nth-child(1){color: #000;}.tab_cation>view:nth-child(2){color: #fff;}.tab_cation>view:nth-child(3){left: 50%;}#myCanvas{position: absolute;left: 0;top: -71vh;z-index: -1;opacity: 0;}

.js

Page({  data: {    canvas_arr:{      src:'',      width:parseInt(wx.getSystemInfoSync().windowWidth * 0.9),      height:parseInt(wx.getSystemInfoSync().windowHeight * 0.7),      show:false    },    cutting:{      height:0,      max_y:0,      show:false    },    canvas_y:0,    color_status:false,    canfile_image:'',  },  color_tap(e){    var type = e?e.currentTarget.dataset.type:0    if(type == 1){      this.setData({        color_status:!this.data.color_status      })    }else{      this.data.canvas_arr.show = false      this.data.canvas_arr.height = parseInt(wx.getSystemInfoSync().windowHeight * 0.7)      this.data.cutting.show = false      this.data.cutting.src = ''      this.setData({        canvas_arr:this.data.canvas_arr,        cutting:this.data.cutting,        canvas_y:0,      })    }  },  setTouchMove(e){return;},  uploadtap(e){    var that = this    wx.chooseImage({      count:1,      success (res) {        const tempFilePaths = res.tempFilePaths[0]        that.data.canvas_arr.src = tempFilePaths        wx.getImageInfo({          src: tempFilePaths,          success (res) {            that.data.canvas_arr.show = true            that.data.cutting.show = true            that.data.cutting.height = that.data.canvas_arr.width / 2            var height = parseInt(res.height / (res.width / that.data.canvas_arr.width))            that.data.canvas_arr.height = height > that.data.canvas_arr.height ? that.data.canvas_arr.height : height            that.data.cutting.max_y = that.data.canvas_arr.height - that.data.cutting.height            that.setData({              canvas_arr:that.data.canvas_arr            })            setTimeout(function () {              that.setData({                cutting:that.data.cutting              })            },500)          }        })      }    })  },  handletouchstart: function (e) {    this.data.startY = e.touches[0].clientY  },  handletouchmove (e) {    let currentY = e.touches[0].clientY - this.data.startY    if(currentY > 0){      this.setData({        canvas_y:currentY > this.data.cutting.max_y?this.data.cutting.max_y:currentY,      })    }else{      this.setData({        canvas_y:0      })    }  },  ationimg(e){    var that = this    var canvas_img = wx.createCanvasContext('myCanvas')    canvas_img.width = that.data.canvas_arr.width    canvas_img.height = that.data.canvas_arr.height    canvas_img.drawImage(that.data.canvas_arr.src,0,0,canvas_img.width,canvas_img.height)    canvas_img.draw(true,(()=>{      wx.canvasToTempFilePath({        x: 0,        y: that.data.canvas_y,        width:that.data.canvas_arr.width,        height:that.data.cutting.height,        canvasId: 'myCanvas',        success: function (res) {          that.setData({            canfile_image:res.tempFilePath          })          that.color_tap()          wx.showToast({            title: '裁剪成功~',            icon: 'none',            duration: 3000          })        }      });    }))  },})

功能主要针对轮播图片尺寸，不合适可自行修改比例

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