C#.Net 从 URL 下载图像，裁剪和上传，无需保存或显示

Question

I have a large number of images on a Web server that need to be cropped. I would like to automate this process.

So my thought is to create a routine that, given the URL of the image, downloads the image, crops it, then uploads it back to the server (as a different file). I don't want to save the image locally, and I don't want to display the image to the screen.

I already have a project in C#.Net that I'd like to do this in, but I could do.Net Core if I have to.

I have looked around, but all the information I could find for downloading an image involves saving the file locally, and all the information I could find about cropping involves displaying the image to the screen.

Is there a way to do what I need?

Answer 1

It's perfectly possible to issue a GET request to a URL and have the response returned to you as a byte[] using HttpClient.GetByteArrayAsync . With that binary content, you can read it into an Image using Image.FromStream .

Once you have that Image object, you can use the answer from here to do your cropping.

//Note: You only want a single HttpClient in your application 
//and re-use it where possible to avoid socket exhaustion issues
using (var httpClient = new HttpClient())
{
    //Issue the GET request to a URL and read the response into a 
    //stream that can be used to load the image
    var imageContent = await httpClient.GetByteArrayAsync("<your image url>");
    
    using (var imageBuffer = new MemoryStream(imageContent))
    {
        var image = Image.FromStream(imageBuffer);

        //Do something with image
    }
}