Convert macOS NSImage to Avalonia.Media.Imaging.Bitmap

[julianpaulozzi]

I'm creating a desktop only POC project (Windows, macOS and Linux) where I have to access several native resources.

I need to get the native system icon for the files types on each platform's.

In net8.0-windows project this is handled with Vanara.Windows.Shell and #5908 (comment) extension method.

public Bitmap? GetSystemIcon(string fileNameOrExtension)
{
    var systemIcon = ShellImageList.GetSystemIcon(fileNameOrExtension, ShellImageSize.Large);

    return systemIcon?.ToBitmap()?   // System.Drawing.Bitmap
      .ConvertToAvaloniaBitmap();    // Avalonia.Media.Imaging.Bitmap
}

In net8.0-macos the NSWorkspace is accessible but would have to convert NSImage to Avalonia.Media.Imaging.Bitmap.

public Bitmap? GetSystemIcon(string fileNameOrExtension)
{
    var fileExtension = Path.GetExtension(fileNameOrExtension);
    
    // get macOS system file icon
    var icon = NSWorkspace.SharedWorkspace.IconForFileType(fileExtension);
    
    // convert macOS NSImage to Avalonia.Media.Imaging.Bitmap?
}

Any way to get this?

[maxkatz6]

Not the most efficient approach, but you can use representationUsingType:properties: API on NSImage to encode it into png, and then decode with new Bitmap.