c# UWP - Convert byte array to InMemoryRandomAccessStream/IRandomAccessStream

Question

I have a problem converting byte array to InMemoryRandomAccessStream or IRandomAccessStream in windows 8?

This is my code, but It doesn't work :

internal static async Task<InMemoryRandomAccessStream> ConvertTo(byte[] arr) 
{
    InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
    
    Stream stream = randomAccessStream.AsStream();
    
    await stream.WriteAsync(arr, 0, arr.Length);
    await stream.FlushAsync();

    return randomAccessStream;
}

And I created the RandomAccessStreamReference and set the requst datapack in order to share the image to other app

private static async void OnDeferredImageStreamRequestedHandler(DataProviderRequest Request) 
{
    DataProviderDeferral deferral = Request.GetDeferral();
    InMemoryRandomAccessStream stream = await ConvertTo(arr);
    
    RandomAccessStreamReference referenceStream =
            RandomAccessStreamReference.CreateFromStream(stream);
    
    Request.SetData(referenceStream);
}

There's no exception but I can't use the result image byte array

I think there's an error when converting byte[] to InMemoryRandomAccessStream, but it doesn't throw an exception.

Anybody know how to implement it?

if anyone knows how to convert the byte array to IRandomAccessStream, it's also appreciated

Solution 1

Add the using statement at the top of the document.

using System.Runtime.InteropServices.WindowsRuntime;
internal static async Task<InMemoryRandomAccessStream> ConvertTo(byte[] arr)
{
    InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
    await randomAccessStream.WriteAsync(arr.AsBuffer());
    randomAccessStream.Seek(0); // Just to be sure.
                    // I don't think you need to flush here, but if it doesn't work, give it a try.
    return randomAccessStream;
}

Solution 2

On Windows 8.1 it's even easier as we added the AsRandomAccessStream extension method:

internal static IRandomAccessStream ConvertTo(byte[] arr)
{
    MemoryStream stream = new MemoryStream(arr);
    return stream.AsRandomAccessStream();
}

Solution 3

In one line:

internal static IRandomAccessStream ConvertTo(byte[] arr)
{
    return arr.AsBuffer().AsStream().AsRandomAccessStream();
}

Comments

[Security Hound]

What exactly is wrong with the code you have?

[Farhan Ghumra]

Please check this & tell me if you can solve the issue.

[tibel]

This seems not to work for some scenarios, as described in stackoverflow.com/questions/22332217/…

[Konstantin S.]

It looks like an action that copies the data three times. You need to check that this is not happening in order for the answer to be usable.