如何使用经典 ASP 保存画布图像?

问题描述

我有点卡在这里.我知道我可以使用 canvas.toDataURL 生成一个 base64 编码的字符串，以传递给我服务器上的经典 ASP 页面.但我似乎找不到答案的问题是如何处理这些数据，以便我可以将其保存在我的服务器上的某个位置.

I'm a bit stuck here. I know that I can use the canvas.toDataURL to produce a base64 encoded string to pass to a classic ASP page on my server. But the problem I can't seem to find an answer to is how to process this data so I can save it someplace on my server.

因此，使用我的 HTML 页面上的这段代码，我提取了画布数据(我从 StackOverflow 的另一篇文章中提取了这个):

So with this snippet of code on my HTML page, I pull the canvas data (I pulled this from another post here at StackOverflow):

var dataURL = renderedCanvas.toDataURL("image/png");    
dataURL = dataURL.replace('data:image/png;base64,', '');

var areturn = $.ajax({
  url: "http://127.0.0.1/mySite/saveImage.asp",
  type: "POST",
  data: '{ "imageData" : "' + dataURL + '" }',
  dataType: "json",
  beforeSend: function(x) {
      x.overrideMimeType("application/j-son;charset=UTF-8");
  }
}).done(function(result) {
    console.log("Success Done!
" + result);
}).always(function(data) {
    console.log("Always:
" + data.responseText);
}); 

但是我现在不清楚一旦我在服务器端如何处理数据......我可以提取 Request.Form 元素，但我似乎找不到任何 base64 解码的好方法它，甚至将其输出为二进制文件...我想我听说经典的 ASP 不擅长进行 base64 解码，在另一个测试中我确实找到了一个可以进行 base64 解码的函数，但我不能不知道它是否真的有效，但它确实需要很长时间才能运行.我还在这里找到了这个链接:用于 ASP 经典的 base64 图像解码器，但我猜这是微软不推荐使用的 32 位组件……我想我正在向社区寻求有关将 html5 画布图像保存到服务器上的建议.

But I'm unclear now what to do with the data once I'm on the server side... I can pull the Request.Form element, but I can't seem to find a good way to either base64 decode it, or even output it as a binary file... I guess I've heard that classic ASP isn't any good at doing base64 decoding, and in another test I did find a function that did the base64 decode, but I couldn't tell if it really worked, but it did take a long time to run. I also found this link here: base64 image decoder for ASP classic, but I guess this is a 32bit component that Microsoft doesn't recommend using... I guess I'm looking to the community here for suggestions on saving out an html5 canvas image onto the server.

推荐答案

您可以使用通过 DomDocument 实例创建的指定 bin.base64 数据类型的 XML 元素来编码/解码 Base64 数据.
然后，您可以使用 Stream 对象将获得的二进制文件保存到磁盘.
这两个库都支持 64 位.假设您发送的内容将在服务器端的 Request 集合(没有 json 的经典 post 方法等)中可用，下面的代码可以解决问题，或者在最坏的情况下，我相信这会给您带来洞察力.

You could use an XML element specifying bin.base64 data type that created through a DomDocument instance to encoding / decoding Base64 data.
Then you can save obtained binary to disk using a Stream object.
Both of these libraries are 64 bit supported. Assuming the content you sent will be available in a Request collection (classic post methods without json etc.) on the server-side, following code solves the problem or at worst I'm sure that gives you insight.

saveImage.asp

Function Base64Data2Stream(sData)
    Set Base64Data2Stream = Server.CreateObject("Adodb.Stream")
        Base64Data2Stream.Type = 1 'adTypeBinary
        Base64Data2Stream.Open
    With Server.CreateObject("MSXML2.DomDocument.6.0").createElement("b64")
        .dataType = "bin.base64"
        .text = sData
        Base64Data2Stream.Write .nodeTypedValue 'write bytes of decoded base64 to stream
        Base64Data2Stream.Position = 0
    End With
End Function

Dim CanvasStream
Set CanvasStream = Base64Data2Stream(Request.Form("imageData"))

'Write binary to Response Stream
'Response.BinaryWrite CanvasStream.Read

'Write binary to File
CanvasStream.SaveToFile Server.Mappath("imgFileFromCanvas.png"), 2 'adSaveCreateOverWrite

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