//1.将div转成svg

var data = "data:image/svg+xml," +

"" +

"" +

"

"" +

"";

var img = new Image();

img.src = data;

document.getElementsByTagName('body')[0].appendChild(img);

//2.svg转成canvas

var canvas = document.createElement('canvas');  //准备空画布

canvas.width = img.width;

canvas.height = img.height;

var context = canvas.getContext('2d');  //取得画布的2d绘图上下文

context.drawImage(img, 0, 0);

var a = document.createElement('a');

a.href = canvas.toDataURL('image/png');  //将画布内的信息导出为png图片数据

a.download = "MapByMathArtSys";  //设定下载名称

//3. 图片导出为 png 格式

var type = 'png';

var imgData = canvas.toDataURL(type);

/**

* 获取mimeType

* @param  {String} type the old mime-type

* @return the new mime-type

*/

var _fixType = function (type) {

type = type.toLowerCase().replace(/jpg/i, 'jpeg');

var r = type.match(/png|jpeg|bmp|gif/)[0];

return 'image/' + r;

};

// 加工image data，替换mime type

imgData = imgData.replace(_fixType(type), 'image/octet-stream');

/**

* 在本地进行文件保存

* @param  {String} data     要保存到本地的图片数据

* @param  {String} filename 文件名

*/

var saveFile = function (data, filename) {

var save_link = document.createElementNS('http://www.w3.org/1999/xhtml', 'a');

save_link.href = data;

save_link.download = filename;

var event = document.createEvent('MouseEvents');

event.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);

save_link.dispatchEvent(event);

};

// 下载后的图片名

var filename = 'LoveCrystal_' + (new Date()).getTime() + '.' + type;

// download

saveFile(imgData, filename);