<div class="page uploader js_show">
  <div class="page__hd">
    <h1 class="page__title">Uploader</h1>
    <p class="page__desc">上传组件，一般配合<a class="link" href=" " rel="external nofollow" >组件Gallery</a >来使用。</p >
  </div>
  <div class="page__bd">
    <div class="weui-gallery" id="gallery" style="opacity: 0; display: none;">
      <span class="weui-gallery__img" id="galleryImg" style="background-image:url(./images/pic_160.png)"></span>
      <div class="weui-gallery__opr">
        <a href="javascript:" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="weui-gallery__del">
          <i class="weui-icon-delete weui-icon_gallery-delete"></i>
        </a >
      </div>
    </div>

    <div class="weui-cells weui-cells_form">
      <div class="weui-cell">
        <div class="weui-cell__bd">
          <div class="weui-uploader">
            <div class="weui-uploader__hd">
              <p class="weui-uploader__title">图片上传</p >
              <div class="weui-uploader__info">0/2</div>
            </div>
            <div class="weui-uploader__bd">
              <ul class="weui-uploader__files" id="uploaderFiles">
                <li class="weui-uploader__file" style="background-image:url(./images/pic_160.png)"></li>
                <li class="weui-uploader__file" style="background-image:url(./images/pic_160.png)"></li>
                <li class="weui-uploader__file" style="background-image:url(./images/pic_160.png)"></li>
                <li class="weui-uploader__file weui-uploader__file_status" style="background-image:url(./images/pic_160.png)">
                  <div class="weui-uploader__file-content">
                    <i class="weui-icon-warn"></i>
                  </div>
                </li>
                <li class="weui-uploader__file weui-uploader__file_status" style="background-image:url(./images/pic_160.png)">
                  <div class="weui-uploader__file-content">50%</div>
                </li>
              </ul>
              <div class="weui-uploader__input-box">
                <input id="uploaderInput" class="weui-uploader__input" type="file" accept="image/*" multiple="">
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
  <div class="page__ft j_bottom">
    <a href="javascript:home()" rel="external nofollow" >< img src="/UploadFiles/2021-04-02/icon_footer_link.png">

观察上面的代码，外层样式直接套用，核心功能块如下：


图片预览/删除部分：




<div class="weui-gallery" id="gallery">
 <!--显示预览-->
 <span class="weui-gallery__img" id="galleryImg"></span>
 <!--删除按钮-->
 <div class="weui-gallery__opr">
  <a href="javascript:" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="weui-gallery__del">
   <i class="weui-icon-delete weui-icon_gallery-delete"></i></a >
 </div>
</div>
图片缩略图列表部分：
 <ul class="weui-uploader__files" id="uploaderFiles">
  <!--每张图片是一个<li>标签-->
  <li class="weui-uploader__file" style="background-image:url(./images/pic_160.png)"></li>
</ul>


有了上面的准备，下载就可以对功能进行实现了:


1. 图片缩略图显示
观察源码可知，每张图片的缩略图的代码结构如下：




<li class="weui-uploader__file" style="background-image:url(./images/pic_160.png)"></li>


他将图片的url直接放到了background-img:url()属性中，样式直接使用微信的官方ui的class。因此，我们可以做这样操作：创建一个数组存picturesUrl放图片的url，用angular2的指令*ngFor根据数组中的内容动态生成缩略图列表（注意picturesUrl中元素的格式为：url(图片的url)）：，图片url数组中的每个元素依次存进中间变量img中，然后使用angular2指令[ngStyle]根据img的值生成预览图，主要代码如下：




<ul class="weui-uploader__files picture-preview" id="uploaderFiles" >
                <li *ngFor="let img of picturesUrl"
                  class="weui-uploader__file"
                  [ngStyle]="{'background-image':img}">
                </li>
</ul>

<!--img实例-->
<!--'url(http://upload-images.jianshu.io/upload_images/7166236-ed8a621900728c39.jpg"htmlcode">

picturesUrl = [
  'url(http://upload-images.jianshu.io/upload_images/7166236-40ed406c30ef20a0.jpg"touchEvent()"，用于监听用户的点击，实现点击退出预览的功能。主要代码如下：


微信的做法（根据点击页面获取到的代码）：




<!--预览隐藏的样式-->
<div class="weui-gallery" id="gallery" style="opacity: 0; display: none;">
 
</div>

<!--预览显示的样式-->
<div class="weui-gallery" id="gallery" style="display: block; opacity: 1;">
 
</div>




我采用的做法：




<div class="weui-gallery" id="gallery" style="display: block"
       *ngIf="shown">
      <span class="weui-gallery__img" (click)="touchEvent()" [ngStyle]="{'background-image':selectImageUrl}"></span>
      <div class="weui-gallery__opr">
        <a href="javascript:" rel="external nofollow" rel="external nofollow" rel="external nofollow" (click)="onDelete()" class="weui-gallery__del">
          <i class="weui-icon-delete weui-icon_gallery-delete"></i>
        </a >
      </div>
</div>





//点击缩略图显示预览
 showPicture($event){
  console.log("$event.target.backgroundImage：" + $event.target.style.backgroundImage);
  this.selectImageUrl = $event.target.style.backgroundImage;
  this.shown = true;
 }

//点击屏幕退出预览
touchEvent(){
  this.shown = false;
 }



3. 图片删除
图片删除的主要代码嵌套在图片预览的代码块中，只要为删除部分绑定一个点击事件（(click)="onDelete()"），点击时出发删除并且退出预览即可。




onDelete(){
  if(isUndefined(this.selectImageUrl)){
   console.log("查看图片预览，图片url未定义，this.selectImageUrl：" + this.selectImageUrl);
   return;
  }
 //正则去除URL中的双引号
  this.selectImageUrl = this.selectImageUrl.replace(/"/g,"");
  console.log("(this.picturesUrl.indexOf(this.selectImageUrl):"+this.picturesUrl.indexOf(this.selectImageUrl));
  //判断图片URL是否存在
  if(this.picturesUrl.indexOf(this.selectImageUrl)!== -1){
   this.picturesUrl.splice(this.picturesUrl.indexOf(this.selectImageUrl) , 1);
   setTimeout(()=>{
     this.shown = false;
    },
    20);
  }else{
   console.log("删除图片出错，获取URL或URL格式出错出错：" + this.selectImageUrl )
  }
 }



效果如下：
显示缩略图：
 
显示预览：
 
点击下面的删除栏：



好了，有时间再附上源码和在线demo。


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。

                                
                                

                                    Angular,图片上传,Angular,图片预览,Angular仿微信图片上传 
                                
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