[BUG] Android: DrawingView.GetImageStream() has a black instead of transparent background

[schnuch]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

1. Draw lines on a DrawingView with a transparent background
2. Generate stream with GetImageStream()
3. Use this stream as an ImageSource or save it to a file
4. The background of the new image is black

• Trying this on a windows build works as expected
• Using any color but transparent as a background works as expected

Expected Behavior

The generated image should have a transparent background.

Steps To Reproduce

1. Run solution from linked reproduction repository
2. Click "Save" button
3. New image is shown below the button

Link to public reproduction project repository

https://github.com/schnuch/MauiRepro/tree/TransparentDrawingView

Environment

- .NET MAUI CommunityToolkit: 5.2.0
- OS: Windows 10.0.19041.0 / Android 11.0
- .NET MAUI: 7.0.86

Anything else?

No response