【JavaScript-ES6】------- JavaScript 使用canvas技术进行压缩图片大小

我会带着你远行 2022-10-02 06:50 114阅读 0赞

> ## 使用canvas压缩图片大小(转载处：[https://www.xuanmo.xin/details/3189][https_www.xuanmo.xin_details_3189]) ##

>  （效果图）![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MzY2NjU3_size_16_color_FFFFFF_t_70][]

>     <!DOCTYPE html>
>     <html lang="en">
>     <head>
>         <meta charset="UTF-8">
>         <meta name="viewport" content="width=device-width, initial-scale=1.0">
>         <meta http-equiv="X-UA-Compatible" content="ie=edge">
>         <title>canvas压缩图片大小</title>
>     </head>
>     <body>
>         <div class="yimage">
>             <form id="form">
>                 <input type="file" name="file"  multiple="multiple">
>             </form>
>         </div>
>         <div class="image">
>              <img src="" width="50%" height="30%">
>         </div>
>         <div class="ysimage">
>                 <img src="">
>         </div>
>         <script src="jquery-1.10.2.min.js"></script>
>         <script type="module">
>          
>                 /**
>                 * [imageCompress 图片压缩]
>                 * @param  {[Array]} imgSrc       [传入图片地址]
>                 * @param  {Number} [width=1024]  [图片需要压缩的宽度,单位：px]
>                 * @param  {Number} [quality=1]   [图片需要压缩的质量，0~1之间]
>                 * @return {[type]}               [返回base64 jpeg格式图片]
>                 */
>                 export function imageCompress (imgSrc, width = 1024, quality = 1) {
>                 let imgList = []
>                 imgSrc.map(v => {
>                     let img = new Promise((resolve, reject) => {
>                     let canvas = document.createElement('canvas')
>                     let ctx = canvas.getContext('2d')
>                     let oImg = new window.Image()
>                     oImg.src = v
>                     oImg.onload = function () {
>                         let height = width / (this.naturalWidth / this.naturalHeight)
>                         // 如果压缩的宽度大于图片自身的宽度，采取图片自身的宽度
>                         if (this.naturalWidth <= width) {
>                         width = this.naturalWidth
>                         height = this.naturalHeight
>                         }
>                         canvas.width = width
>                         canvas.height = height
>                         ctx.drawImage(this, 0, 0, width, height)
>                         resolve(canvas.toDataURL('image/jpeg', quality))
>                     }
>                     })
>                     imgList.push(img)
>                 })
>                 return Promise.all(imgList).then(res => Promise.resolve(res))
>                 }
>                 
>             $(document).ready(function(){
>                
>                // imageCompress("/timg.jpg");
>     
>                $("input[name='file']").on("change",function(){
>                     var reader = new FileReader();
>                      reader.onload = function(e) {
>                        var data=[];
>                        data.push(e.target.result);
>                        $(".image").find("img").attr("src",e.target.result);
>                        var imgebase4=imageCompress(data,300,0.3);
>                        imgebase4.then(
>                                 function (val) {
>                                     $(".ysimage").find("img").attr("src",val[0]);
>                                 },
>                                 function (reason) {
>                                   //  console.log('Handle rejected promise (' + reason + ') here.');
>                                 });
>                      }             
>                      reader.readAsDataURL(document.querySelector("input[type=file]").files[0]);
>                });
>             })
>            
>     
>             
>         </script>
>     </body>
>     </html>
> 
>

[https_www.xuanmo.xin_details_3189]: https://www.xuanmo.xin/details/3189
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MzY2NjU3_size_16_color_FFFFFF_t_70]: /images/20220113/05b615f99b8f43098563ba4c38ec1180.png