I'm finding it awfully hard to see how to simply cover a rectangular XAML element with repeating copies of a bitmap! I am using WinUI 3 with Windows App SDK. I would like to use the repeating image as a background element in my app.

It would seem to involve the composition API. Some tantalizing clues are given by

The image is 32x32 and the canvas is 128x128 so we have 4x4 tiles.