JS图片压缩 

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <title>File API Test</title>
    <script type="text/javascript" src="jquery-1.11.0.min.js"></script>
    <script type="text/javascript" src="de.js"></script>
    <style>
        #test{
            width:100px;
            height:100px;
        }
    </style>
</head>
<body>
<input type="file" id="fileImg" >
<form>
    <img src="" id="test" alt="">
</form>
<script>
    function handleFileSelect (evt) {
        console.log( document.getElementById("fileImg").files);
        // var filebtn = document.getElementById(id);
        // console.log(filebtn);
        // var files = filebtn.target.files;
        // console.log(filebtn.target);
        // console.log(files);
        var files = evt.target.files;
        for (var i = 0, f; f = files[i]; i++) {
 
          // Only process image files.
          if (!f.type.match('image.*')) {
            continue;
          }
 
          var reader = new FileReader();
 
          // Closure to capture the file information.
          reader.onload = (function(theFile) {
            return function(e) {
              // Render thumbnail.
              // console.log(evt.target.files[0]);
              // console.log(e.target);
              console.log(e.target.result);
              var i = document.getElementById("test");
              i.src = event.target.result;
              console.log($(i).width());
              console.log($(i).height());
              $(i).css('width',$(i).width()/10+'px');
              //$(i).css('height',$(i).height()/10+'px');
              console.log($(i).width());
              console.log($(i).height());
              var quality =  50;
              i.src = jic.compress(i,quality).src;
              console.log(i.src);
              i.style.display = "block";
            };
          })(f);
 
          // Read in the image file as a data URL.
          reader.readAsDataURL(f);
        }
      }
 
    document.getElementById('fileImg').addEventListener('change', handleFileSelect, false);
</script>
</body>
</html>

de.js

var jic = {
        /**
         * Receives an Image Object (can be JPG OR PNG) and returns a new Image Object compressed
         * @param {Image} source_img_obj The source Image Object
         * @param {Integer} quality The output quality of Image Object
         * @return {Image} result_image_obj The compressed Image Object
         */
 
        compress: function(source_img_obj, quality, output_format){
             
             var mime_type = "image/jpeg";
             if(output_format!=undefined && output_format=="png"){
                mime_type = "image/png";
             }
             
 
             var cvs = document.createElement('canvas');
             //naturalWidth真实图片的宽度
             cvs.width = source_img_obj.naturalWidth;
             cvs.height = source_img_obj.naturalHeight;
             var ctx = cvs.getContext("2d").drawImage(source_img_obj, 0, 0);
             var newImageData = cvs.toDataURL(mime_type, quality/100);
             var result_image_obj = new Image();
             result_image_obj.src = newImageData;
             return result_image_obj;
        },
       function (){}
}

 这是在网上摘抄的完整代码，可以直接运行成功。

posted @ 2017-11-17 17:13  申小贺  阅读(245)  评论(0)  编辑  收藏  举报