使用.Net框架判断文件是否是图像，而不是通过检查幻数
由于实际加载图像的所有智能都是由 .net 框架完成的，似乎我不必在代码中通过检查幻数或使用这样的黑客来重复这一切：
Private Function IsImage(FileName as String) As Boolean
Try
Using img As New Bitmap(FileName)
End Using
Catch ex as System.ArgumentException
Return False
End Try
Return True
End Function
我是否遗漏了一些明显的东西，例如System.Drawing.IsImage(stream)？
With all the smarts of actually loading images being done by the .net framework, seems like I shouldn't have to repeat it all in my code by checking for magic numbers, or using a hack like this:
Private Function IsImage(FileName as String) As Boolean
Try
Using img As New Bitmap(FileName)
End Using
Catch ex as System.ArgumentException
Return False
End Try
Return True
End Function
Am I missing something obvious, like System.Drawing.IsImage(stream)?
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您需要打开文件并读取您想要支持的文件类型的相关标头，如下所述：
确定文件是否是图像
我认为 .NET 框架中除了将其加载到图像中并查询图像格式之外，没有任何东西可以为您执行此操作：
在 C# 中使用 Bitmap 对象查找图像格式
另一种理论 (没有实际事实来支持这一点）：也许 Windows 中的文件包含将其标记为图像的元数据 - 与属性对话框似乎显示音频文件的艺术家信息的方式相同。这可能是避免打开文件的一个可爱的方法。
由 FastAl 2020 年 6 月编辑。更多有用链接：
使用.NET，如何根据文件签名而不是扩展名找到文件的 mime 类型
不是我要求的，但这里有神奇的 # s:
https://en.wikipedia.org/wiki/List_of_file_signatures
https://www.garykessler.net/library/file_sigs.html
You will need to open up the file and read the relevant headers for the file types you want to support, as mentioned here:
determine if file is an image
I don't think there is anything already in the .NET framework that can do this for you, other than loading it into an image and querying the image format:
Find image format using Bitmap object in C#
An alternative theory (no actual facts to back this one up): perhaps the file in Windows holds meta-data that flags it as an image - in the same manner than the properties dialog seems to show artist information for audio files. This could be a cute way to avoid opening the file.
Edit by FastAl Jun 2020. More useful links:
Using .NET, how can you find the mime type of a file based on the file signature not the extension
Not what I asked for, but here are the magic #s:
https://en.wikipedia.org/wiki/List_of_file_signatures
https://www.garykessler.net/library/file_sigs.html