base64支持压缩尺寸上传

JavaScript

/*
 * @param m_this当前对象
 * @param id展示图片id
 * @param wid压缩后宽度
 * @param quality压缩质量 
 * */  
function cutImageBase64(m_this,id,wid,quality) {
    var file = m_this.files[0];
    var URL = window.URL || window.webkitURL;
    var blob = URL.createObjectURL(file);
    var base64;

    var img = new Image();
    img.src = blob;
    img.onload = function() {
        var that = this;

        //生成比例
        var w = that.width,
            h = that.height,
            scale = w / h;
            w = wid || w;
            h = w / scale;

        //生成canvas
        var canvas = document.createElement('canvas');
        var ctx = canvas.getContext('2d');
        $(canvas).attr({
            width: w,
            height: h
        });
        ctx.drawImage(that, 0, 0, w, h);

        // 生成base64            
        base64 = canvas.toDataURL('image/jpeg', quality || 0.8);

        $(id).attr('src',base64);
    };
}

 //调用 
 $(id).on('change',function(){
     var m_this = this;
     cutImageBase64(m_this,'#com_ImgPr03',400,0.8);  
 })