从文件扩展名中获取ImageFormat [英] Get ImageFormat from File Extension

问题描述

是否有快速方法将ImageFormat对象与特定文件扩展名相关联？我正在寻找比每种格式更快的字符串比较。

Is there quick way to get the ImageFormat object associated to a particular file extension? I'm looking for quicker than string comparisons for each format.

推荐答案

以下是我发现的一些旧代码应该可以解决的问题：

Here's some old code I found that should do the trick:

 string InputSource = "mypic.png";
 System.Drawing.Image imgInput = System.Drawing.Image.FromFile(InputSource);
 Graphics gInput = Graphics.fromimage(imgInput);
 Imaging.ImageFormat thisFormat = imgInput.RawFormat;

这需要实际打开并测试图像 - 文件扩展名被忽略。假设你正在打开文件，这比信任文件扩展名要强大得多。

This requires actually opening and testing the image--the file extension is ignored. Assuming you are opening the file anyway, this is much more robust than trusting a file extension.

如果你没有打开文件，就没有什么更快了（在一个性能感）而不是字符串比较 - 当然不会调用操作系统来获取文件扩展名映射。

If you aren't opening the files, there's nothing "quicker" (in a performance sense) than a string comparison--certainly not calling into the OS to get file extension mappings.

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