How to get the Image Width & Height when doing Upload in asp.net core

Question

I am making a page in asp.net core that is uploading images to server using input type file html control.

<form method="post" asp-action="Add" enctype="multipart/form-data">
    <input type="file" name="mediaUpload" />
    <button type="submit">Submit</button>
</form>

I have also added the System.Drawing for .NET Core dll from NuGet.

Now on my post action I want to get the image Width & Height. This is the below code for it (but its now working).

[HttpPost]
public ActionResult Add(IFormFile mediaUpload)
{
    Image image = Image.FromStream(file.OpenReadStream); // error is here
    int width = image.Width;
    int height = image.Height;
}

The complile time error -

Severity Code Description Project File Line Suppression State Error CS1503 Argument 1: cannot convert from 'method group' to 'Stream' Goldentaurus E:\Website\Goldentaurus\Goldentaurus\Controllers\MediaController.cs 453 Active

Please help??

Note: My previous ASP.NET MVC 5 application(code shown below) was using a similar code that was working very well. I modified it to the above code to work on asp.net core.

[HttpPost]
public ActionResult Add(HttpPostedFileBase mediaUpload)
{
    Image image = Image.FromStream(file.InputStream);
    int width = image.Width;
    int height = image.Height;
}

OpenReadStream is a function, so you need to add () to invoke it. — Kirk Larkin
– Kirk Larkin, Commented May 16, 2018 at 18:33

kudzanayi · Accepted Answer · 2018-10-29 22:06:10Z

You can try this link https://andrewlock.net/using-imagesharp-to-resize-images-in-asp-net-core-a-comparison-with-corecompat-system-drawing/ it explains how to use CoreCompat.System.Drawing which is what you are supposed to use for .net core. It also compares it with ImageSharp. I used ImageSharp because I dont have to specify the operating system as is required in CoreCompat.System.Drawing, here is how I got it to work using the nuget package SixLabors.ImageSharp 1.0.0-beta0005 (make sure the Include prerelease is box in nugget is checked)

 private async Task<(int height, int width)> GetImageDimentions(IFormFile file)
    {
        if (file != null)
        {
            List<string> AcceptableImageExtentions = new List<string> { ".jpg", ".jpeg", ".png", ".bmp" };

            string fileExtention = System.IO.Path.GetExtension(file.FileName);

            if (AcceptableImageExtentions.Contains(fileExtention))
            {
                using (System.IO.Stream stream = new System.IO.MemoryStream())
                {
                    await file.CopyToAsync(stream);
                    SixLabors.ImageSharp.Formats.IImageDecoder imageDecoder;

                    if (fileExtention == ".jpeg" || fileExtention == ".jpg")
                    {
                        imageDecoder = new SixLabors.ImageSharp.Formats.Jpeg.JpegDecoder();
                    }
                    else if (fileExtention == ".png")
                    {
                        imageDecoder = new SixLabors.ImageSharp.Formats.Png.PngDecoder();
                    }
                    else
                    {
                        imageDecoder = new SixLabors.ImageSharp.Formats.Bmp.BmpDecoder();
                    }


                    if (stream.Position == stream.Length) //Check this because if your image is a .png, it might just throw an error
                    {
                        stream.Position = stream.Seek(0, SeekOrigin.Begin);
                    }

                    SixLabors.ImageSharp.Image<SixLabors.ImageSharp.PixelFormats.Rgba32> imageSharp = imageDecoder.Decode<SixLabors.ImageSharp.PixelFormats.Rgba32>(Configuration.Default, stream);

                    if (imageSharp != null)
                    {
                        return (imageSharp.Height, imageSharp.Width);
                    }
                }
            }
        }
        return (0, 0);
    }

You can also read https://blogs.msdn.microsoft.com/dotnet/2017/01/19/net-core-image-processing/ Hope it helps

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