最近項目中須要實現一個下載圖片的功能(以下圖)canvas
一開始考慮使用a標籤的download屬性進行下載:跨域
<a href="圖片src" download="下載海報"> 下載海報 </a>
可是經過測試,發現再safari中,下載的文件不能帶上拓展名,因此只好換一個思路,使用canvas進行處理。測試
1.圖片須要添加crossOrigin='anonymous'設置圖像的跨域屬性spa
img.crossOrigin = 'anonymous';
2.使用toDataURL把圖片轉換成base64格式code
canvas.toDataURL("image/png")
3.使用模擬點擊事件,觸發下載orm
var save_link = document.createElement('a'); save_link.href = image; save_link.download ='測試.png'; var clickevent = document.createEvent('MouseEvents'); clickevent.initEvent('click', true, false); save_link.dispatchEvent(clickevent);
完整代碼:事件
var canvas = $('.canvas'); var cxt = canvas[0].getContext("2d"); function save(){ var img = new Image(); img.crossOrigin = 'anonymous'; img.onload = function(){ var _w = img.naturalWidth; var _h = img.naturalHeight; canvas.attr({width:_w,height:_h}); cxt.drawImage(img,0,0); var image = canvas[0].toDataURL("image/png") var save_link = document.createElement('a'); save_link.href = image; save_link.download ='測試.png'; var clickevent = document.createEvent('MouseEvents'); clickevent.initEvent('click', true, false); save_link.dispatchEvent(clickevent); }; img.src = 'http://n.sinaimg.cn/sports/transform/20170825/NZI3- fykiufe6650492.jpg'; }