c# - 如何将 html2canvas 图像保存到 jquery 中的系统文件夹中

Question

我在这个表单中有一个带有 id="form1"的表单我有一个图表。现在我正在使用 html2canvas 来获取这个 form1 的图像。这是我的代码..

<script type="text/javascript">

      $(document).ready(function () {
          $('#add_button').click(function () {
              alert("hiii");
              $('form1').html2canvas();
              var queue = html2canvas.Parse();
              var canvas = html2canvas.Renderer(queue, { elements: { length: 1} });
              var img = canvas.toDataURL();
              window.open(img);
              alert("Hello");
          });
      });

  </script>

<form id="form1" runat="server">
<div style="padding-left:150px">
  <asp:Literal ID="FCLiteral1" runat="server"></asp:Literal>
</div>
<div style="padding-left:350px"><b>Demo</b></div>
</form>

 <input type="submit" id="add_button" value="Take Screenshot Of Div" " />

所以我的问题是如何将此图像保存到我的系统硬盘中..请帮助我。

Answer 1

系统硬盘？没看懂，服务端还是客户端？

客户

如果想让用户自动下载图片，需要修改Data URI scheme

试试这个:

添加CSS

#myHideFrame {
    position: absolute;
    top: -9999px;
    width: 1px;
    height: 1px;
}

在Javascript中添加

var img = canvas.toDataURL();
var frame = document.getElementById("myHideFrame");
if(!frame) {
    frame = document.createElement("iframe");
    frame.id = "myHideFrame";
    document.body.appendChild(frame);
}
frame.src = img.replace(/^data[:]image\/(png|jpg|jpeg)[;]/i, "data:application/octet-stream;");

不幸的是这个例子没有显示名字，为此你必须做这样的事情(用户需要点击链接):

var img = canvas.toDataURL();
var link = document.createElement("a");
link.download = "photo.png"; //Setup name file
link.href = img.replace(/^data[:]image\/(png|jpg|jpeg)[;]/i, "data:application/octet-stream;");
document.body.appendChild(link);

服务器

如果你想保存在服务器上，那么你需要使用Ajax，例如Jquery:

Javascript 文件:

var img = canvas.toDataURL().replace(/^data[:]image\/(png|jpg|jpeg)[;]base64,/i, "");
$.ajax({
    "type": "POST",
    "url": "upload.aspx/UploadImage",
    "data": { 
        "imageData": img //Send to WebMethod
    }
}).done(function(o) {
    console.log(["Response:" , o]); 
});

您的 upload.aspx.cs 文件需要:

...
[WebMethod()]
public static void UploadImage(string imageData)
{
    string fileNameWitPath = "custom_name.png";
    using (FileStream fs = new FileStream(fileNameWitPath, FileMode.Create))
    {
        using (BinaryWriter bw = new BinaryWriter(fs))
        {
            byte[] data = Convert.FromBase64String(imageData);//convert from base64
            bw.Write(data);
            bw.Close();
        }
    }
}
...

查看详情:http://www.dotnetfunda.com/articles/show/1662/saving-html-5-canvas-as-image-on-the-server-using-aspnet