How do I bind byte[] / BitmapImage in Image Source?

[vitkuz573]

An exception is thrown when trying to bind byte[] in Source:

"System.InvalidCastException" in WinRT.Runtime.dll
WinRT information: No such interface supported

Exception thrown: "System.Runtime.InteropServices.COMException" in WinRT.Runtime.dll
WinRT information: No such interface supported

Exception thrown: "System.Runtime.InteropServices.COMException" in System.Private.CoreLib.dll
WinRT information: No such interface supported

Tried to bind BitmapImage:

    public static async Task<BitmapImage> ImageFromBytes(this byte[] bytes)
    {
        var image = new BitmapImage();
 
        using (var stream = new InMemoryRandomAccessStream())
        {
            await stream.WriteAsync(bytes.AsBuffer());
            stream.Seek(0);
            await image.SetSourceAsync(stream);
        }
 
        return image;
    }

And a few other options, but another exception is thrown already:

Exception thrown: "System.Runtime.InteropServices.COMException" in System.Private.CoreLib.dll
Exception thrown: "System.AggregateException" in System.Private.CoreLib.dll
Exception thrown: "System.AggregateException" in System.Private.CoreLib.dll

New to WinUI, I don't understand why it doesn't work

[castorix]

Instead of BitmapImage I generally use WriteableBitmap, like for example in the GetCaptureWriteableBitmap function in
CMediaEngine.cs
(then Image.Source = WriteableBitmap to display it in an Image control)

[vitkuz573]

Here's an example: code from viewmodel:

var bytes = dto.ImageBytes.ToByteArray();

var wb = new WriteableBitmap(1920, 1080);
await wb.PixelBuffer.AsStream().WriteAsync(bytes, 0, bytes.Length);

CurrentScreenshot = wb; // This line causes a `COMException` to be thrown (UPD: not sure)

UPD: COMException is thrown even if you just create a WriteableBitmap instance

[castorix]

If I fill manually the byte array for example with 1 red pixel, it is ok too :

            byte[] pBytes = new byte[4];
            pBytes[0] = 0;
            pBytes[1] = 0;
            pBytes[2] = 255;
            pBytes[3] = 0;
            WriteableBitmap wb = new WriteableBitmap(1, 1);
            await wb.PixelBuffer.AsStream().WriteAsync(pBytes, 0, pBytes.Length);               
            img1.Source = wb;

[vitkuz573]

This only seems to happen when I do it in the ViewModel code, but if I write this code in the *.xaml.cs file, it works. I don't get it. I'll look into it, thanks!

[DarranRowe]

What is the type of CurrentScreenshot? For that kind of assignment to work, it must be along the inheritance hierarchy of WritableBitmap.

[vitkuz573]

What is the type of CurrentScreenshot?

Is an observable property (CommunityToolkit MVVM)

[ObservableProperty]
private WriteableBitmap currentScreenshot;

The thing is that even just creating an instance of WriteableBitmap throws COMException. And this happens only when writing code in ViewModel, but if you do the same in the file *.xaml.cs, then everything works fine

[DarranRowe]

Are the bytes raw pixel bytes or are they the contents of a bitmap file?
The source is assumed to be a bitmap file which has a bitmap header and other metadata, so that is probably why it is failing.
There are several options for getting raw bitmap pixels into an image source though.

1. SoftwareBitmapSource allows you to use a SoftwareBitmap as a source. You can load this using bitmap bits.

2. WritableBitmap allows you to set the size of the bitmap and then access the pixel buffer.

3. SurfaceImageSource allows you to use interop with Direct3D/Direct2D to write to the surface.

[vitkuz573]

Yes, it is a raw array of bytes