从图像源获取流

Question

I want to get a Stream from a StreamImageSource. I took a pic with the phonecamera and show a little preview on the form. Therefore I load the picture stream in a ImageSource.

Now I want to get back the Stream ... but with my approach I always get an exception that "Cannot access a closed Stream"

    private static async Task<Stream> GetStreamFromImageSourceAsync(StreamImageSource imageSource, CancellationToken cancellationToken = default(CancellationToken))
    {
        if (imageSource.Stream != null)
        {
            return await imageSource.Stream(cancellationToken);
        }
        return null;
    }

This is the caller routine

var s = await GetStreamFromImageSourceAsync((StreamImageSource)item.Source);                        
s.Position = 0;

and here i get the exception that i cannot read from a closed stream

thank you guys ...

Answer 1

Once the Stream is consumed to display the preview, it gets closed and you can't use it anymore.

What you can do is, once you get the Stream from the camera, copy it in a MemoryStream , and that MemoryStream can be used and reused at will.