dealImage(getObjectURL(fileObj[0]), {width : 200}, function(base){
$(".testImg").attr("src",base);
})
/**
* 图片压缩,默认同比例压缩
* @param {Object} path
* pc端传入的路径可以为相对路径,但是在移动端上必须传入的路径是照相图片储存的绝对路径
* @param {Object} obj
* obj 对象 有 width, height, quality(0-1) 不传width和 height,图片大小不变只改变像素值
* @param {Object} callback
* 回调函数有一个参数,base64的字符串数据
*/
function dealImage(path, obj, callback){
var img = new Image();img.src = path;
img.onload = function(){
var that = this;
// 默认按比例压缩
var w = that.width,
h = that.height,
scale = w / h;
w = obj.width || w;
h = obj.height || (w / scale);
var quality = 0.3; // 默认图片质量为0.7
//生成canvas
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
// 创建属性节点
var anw = document.createAttribute("width");
anw.nodeValue = w;
var anh = document.createAttribute("height");
anh.nodeValue = h;
canvas.setAttributeNode(anw);
canvas.setAttributeNode(anh);
ctx.drawImage(that, 0, 0, w, h);
// 图像质量
if(obj.quality && obj.quality <= 1 && obj.quality > 0){
quality = obj.quality;
}
// quality值越小,所绘制出的图像越模糊
var base64 = canvas.toDataURL('image/jpeg', quality );
// 回调函数返回base64的值
callback(base64);
}
}