利用HTML5，前端js实现图片压缩

时间：2023-03-09 08:07:36
利用HTML5，前端js实现图片压缩

http://blog.csdn.NET/qazwsx2345/article/details/21827553

主要用了两个HTML5的 API，一个file，一个canvas，压缩主要使用cnavas做的，file是读取文件，之后把压缩好的照片放入内存，最后内存转入表单下img.src，随着表单提交。

照片是自己用单反拍的，5M多，压缩下面3张分别是600多kb，400多kb，300kb的最后那张失真度很大了，压缩效率蛮高的。

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8"/>

    <title>File API Test</title>

    <script type="text/javascript" src="js/jquery-1.11.0.min.js"></script>

    <script type="text/javascript" src="js/JIC.js"></script>

    <style>

        #test{

            display: none;

        }

    </style>

</head>

<body>

<input type="file" id="fileImg" >

<form>

    <img src="" id="test" alt="">

</form>

<script>

    function handleFileSelect (evt) {

        // 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>  

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   ****(***){}

}

相关文章