基于Vue的图片裁剪 vue-cropper

Posted 2022-11-12 北辰浅巷墨漓

今天做项目遇到了这样一个需求：对于要上传的图片进行裁剪，于是发现了一个好的工具----vue-cropper

1. 首先下载vue-cropper

npm install vue-cropper

2. 引入vue-cropper

import  VueCropper  from 'vue-cropper'
export default 
  components: 
    VueCropper
  ,
  

封装成组件uploadPattern.vue

<template>
  <div class="app-container">
      <el-dialog :title="dialogTitle" :visible.sync="open" width="800px" append-to-body @opened="modalOpened" @close="closeDialog">
          <div class="cropper-content">
              <div class="cropper-box">
                <div class="cropper">
                      <vue-cropper
                        ref="cropper"
                        :img="options.img"
                        :info="true"
                        :autoCrop="options.autoCrop"
                        :autoCropWidth="options.autoCropWidth"
                        :autoCropHeight="options.autoCropHeight"
                        :fixedBox="options.fixedBox"
                        @realTime="realTime"></vue-cropper>
                </div>
                <!-- 底部操作工具按钮 -->
                <div class="footer-btn">
                    <div class="scope-btn">
                        <label class="btn" for="uploads">选择图片</label>
                        <input type="file" id="uploads" style="position:absolute; clip:rect(0 0 0 0);" accept="image/png, image/jpeg, image/gif, image/jpg" @change="selectImg($event)">
                        <el-button size="mini" type="danger" plain icon="el-icon-zoom-in" @click="changeScale(1)">放大</el-button>
                        <el-button size="mini" type="danger" plain icon="el-icon-zoom-out" @click="changeScale(-1)">缩小</el-button>
                        <el-button size="mini" type="danger" plain @click="rotateLeft">↺ 左旋转</el-button>
                        <el-button size="mini" type="danger" plain @click="rotateRight">↻ 右旋转</el-button>
                    </div>
                    <div class="upload-btn">
                        <el-button size="mini" type="success" @click="uploadImg('blob')">上传图片 <i class="el-icon-upload"></i></el-button>
                    </div>
                </div>
            </div>
            <!--预览效果图-->
            <div class="show-preview">
                <div :style="previews.div" class="preview">
                    <img :src="previews.url" :style="previews.img">
                </div>
            </div>
          </div>
      </el-dialog>
  </div>
</template>
<script>
// 这里可以导入其他文件（比如：组件，工具js，第三方插件js，json文件，图片文件等等）
import  VueCropper  from 'vue-cropper'
export default 
  components: 
    VueCropper
  ,
  props:
      showModal:Boolean,
      //标题
      title:
          type:String,
          default:''
      
  ,
  // 定义属性
  data() 
    return 
      dialogTitle:'',
      open:false,//上传标签图片对话框
      // 是否显示cropper
      visible: false,
      options: 
        img: '', //裁剪图片的地址
        autoCrop: true, // 是否默认生成截图框
        autoCropWidth: 200, // 默认生成截图框宽度
        autoCropHeight: 200, // 默认生成截图框高度
        fixedBox: true // 固定截图框大小 不允许改变
      ,
      previews: //预览图片
    
  ,
  watch:
      showModal(newVal)
          this.open=newVal;
          this.dialogTitle=this.title;
      
  ,
  // 方法集合
  methods: 
    //实时预览函数
    realTime(data)
        this.previews=data;
    ,
    //打开弹窗层结束时的回调
    modalOpened()
        this.visible=true;
    ,
    //选择图片
    selectImg(e)
        let file=e.target.files[0];
        if(!/\\.(jpg|jpeg|png|JPG|PNG)$/.test(e.target.value))
            this.msgError("文件格式错误，请上传图片类型,如：JPG，PNG后缀的文件。");
        else
            let reader=new FileReader()
            reader.readAsDataURL(file);
            reader.onload = (e)=>
                this.options.img = reader.result;
            
        
    ,
    //放大、缩小图片
    changeScale(num)
        num=num || 1;
        this.$refs.cropper.changeScale(num);
    ,
    //左旋转
    rotateLeft()
        this.$refs.cropper.rotateLeft();
    ,
    //右旋转
    rotateRight()
        this.$refs.cropper.rotateRight();
    ,
    //关闭弹窗
    closeDialog()
        this.$emit('update:showModal',false)
    ,
    //上传图片
    uploadImg(type)
        if(type==='blob')
            this.$refs.cropper.getCropBlob(data=>
                let formData=new FormData();
                formData.append("file",data);
                this.$emit('uploadImg',formData);
                this.closeDialog();
            )
        else
            this.msgError('文件服务异常，请联系管理员')
        
    
  

</script>

<style lang='scss' scoped>
.cropper-content
  display: flex;
  display: -webkit-flex;
  justify-content: flex-end;
  .cropper-box
    flex: 1;
    width: 100%;
    .cropper
      width: auto;
      height: 300px;
    
  

  .show-preview
    flex: 1;
    -webkit-flex: 1;
    display: flex;
    display: -webkit-flex;
    justify-content: center;
    .preview
      overflow: hidden;
      border:1px solid #67c23a;
      background: #cccccc;
    
  

.footer-btn
  margin-top: 30px;
  display: flex;
  display: -webkit-flex;
  justify-content: flex-end;
  .scope-btn
    display: flex;
    display: -webkit-flex;
    justify-content: space-between;
    padding-right: 10px;
  
  .upload-btn
    flex: 1;
    -webkit-flex: 1;
    display: flex;
    display: -webkit-flex;
    justify-content: center;
  
  .btn 
    outline: none;
    display: inline-block;
    line-height: 1;
    white-space: nowrap;
    cursor: pointer;
    -webkit-appearance: none;
    text-align: center;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
    outline: 0;
    -webkit-transition: .1s;
    transition: .1s;
    font-weight: 500;
    padding: 8px 15px;
    font-size: 12px;
    border-radius: 3px;
    color: #fff;
    background-color: #409EFF;
    border-color: #409EFF;
    margin-right: 10px;
  

</style>

效果图如下：

放大之后进行裁剪：

最近遇到了这样一个问题，如果图片是透明的，那选择之后就会变成一片黑

解决办法：加一个属性 outputType为png,输出类型为png格式，这样背景就会是透明的了，如果是jpg格式就会有背景色

:outputType="'png'"