通过js实现压缩图片上传功能

<!-- 首先引入jquery!!!!!!这里没有引入 -->


<img src="/Uploads/verifyinfo/cardz.png" style="width: 100%;height: 100%;">
<input id="cardz" name="cardz" class="weui-uploader__input" type="file" accept="image/*" multiple="">
<input type="hidden" id="cardzbase" name="cardzbase">


<script>
 $(function(){
  $("input[type=file]").on('change', function(){

   var filePath = $(this).val(),     //获取到input的value，里面是文件的路径
       fileFormat = filePath.substring(filePath.lastIndexOf(".")).toLowerCase(),
       fileObj = document.getElementById($(this).attr('id')).files[0]; //上传文件的对象,要这样写才行，用jquery写法获取不到对象

   var imgBase64str = '';   //存储图片的imgBase64
   // 检查是否是图片
   if( !fileFormat.match(/.png|.jpg|.jpeg/) ) {
    alert('上传错误,文件格式必须为：png/jpg/jpeg');
    return;
   }
   var that = this;
   // 调用函数，对图片进行压缩
   compress(fileObj,function(imgBase64){
    imgBase64str = imgBase64;//存储转换后的base64编码

    var reader = new FileReader();
    var img = $(that).prev("img")
    file = that.files[0]
    reader.addEventListener("load", function () {
     img.attr("src",imgBase64str);
     $("#"+$(that).attr('id')+"base").val(imgBase64str);
    }, false);
    reader.readAsDataURL(file)
   });



  })
  $("#uploadcard").on("click", function(){
   var cardzbase = $("#cardzbase").val();
   if (cardzbase.length<=0) {
    $.toast("请添加正面照");
    return;
   }
   $.post(
    "php路径",
    {
     cardzbase:cardzbase
    },
    function (data) {
     alert(data.msg);
    }
   );


  });
 })
 // 对图片进行压缩
 function compress(fileObj, callback){
  if ( typeof (FileReader) === 'undefined') {
   console.log("当前浏览器内核不支持base64图标压缩");
   //调用上传方式不压缩
   directTurnIntoBase64(fileObj,callback);
  } else {
   var reader = new FileReader();
   reader.onload = function (e) { //要先确保图片完整获取到，这是个异步事件


    var image = new Image();
    image.src=e.target.result;
    image.onload = function(){
     square = 0.2,  //定义画布的大小，也就是图片压缩之后的像素
         canvas = document.createElement('canvas'), //创建canvas元素
         context = canvas.getContext('2d'),
         imageWidth = Math.round(square*image.width),  //压缩图片的大小
         imageHeight = Math.round(square*image.height),
         data = '';

     canvas.width = imageWidth;
     canvas.height = imageHeight;
     context.clearRect(0, 0, imageWidth, imageHeight); //在给定矩形内清空一个矩形
     context.drawImage(this, 0, 0, imageWidth, imageHeight);
     var data = canvas.toDataURL('image/jpeg',0.6);
     //压缩完成执行回调

     callback(data);
    };
   };
   reader.readAsDataURL(fileObj);

  }
 }
 // 不对图片进行压缩，直接转成base64
 function directTurnIntoBase64(fileObj,callback){
  var r = new FileReader();
  // 转成base64
  r.onload = function(){
   //变成字符串
   imgBase64 = r.result;
   //console.log(imgBase64);
   callback(imgBase64);
  }
  r.readAsDataURL(fileObj);  //转成Base64格式
 }
</script>

<?php
/**
   * [将Base64图片转换为本地图片并保存]
   * @param $base64_image_content [要保存的Base64]
   * @param $path [要保存的路径]
   * @return bool|string
   */
  public function base64_image_content($base64_image_content,$path){
    //匹配出图片的格式
    if (preg_match('/^(data:\s*image\/(\w+);base64,)/', $base64_image_content, $result)){
      $type = $result[2];
      //生成文件名
      $file_name = random_str(10).".{$type}";
      //路径和文件名拼接
      $local_file_url = $path.$file_name;
      if (file_put_contents($local_file_url, base64_decode(str_replace($result[1], '', $base64_image_content)))){
        return array("filename"=>$file_name,"path"=>$path,"filepath"=>$local_file_url);
      }else{
        return false;
      }
    }else{
      return false;
    }
  }

  public function uploadm()
  {
    $da['status'] = 0;
    if (IS_POST) {
      $infoz = I("post.cardzbase");
      if (!$infoz || !$infof) {
        // 上传错误提示错误信息
//        $this->error($upload->getError());
        $da['msg'] = "上传异常";
      } else {
        $infoz_info = $this->base64_image_content($infoz,"Uploads/verifyinfo/");
        if($infof_info==false){
          $da['msg'] = "上传失败";
        }else{
          //自己的业务...
        }
      }
    }else{
      $da['msg'] = "非法请求";
    }
    $this->ajaxReturn($da);
  }