Border BoxShadow only works with BackgroundSizing=CenterBorder

[amwx]

Describe the bug

Setting BackgroundSizing to anything other than CenterBorder causes the BoxShadow to not render:

To Reproduce

<StackPanel Orientation="Horizontal"
            Spacing="20"
            HorizontalAlignment="Center">

    <Border Background="Gray"
            Width="200" Height="200"
            BoxShadow="0 16 16 0 #35000000">
        <TextBlock Text="CenterBorder"
                   HorizontalAlignment="Center"/>
    </Border>

    <Border Background="Gray"
            Width="200" Height="200"
            BoxShadow="0 16 16 0 #35000000"
            BackgroundSizing="InnerBorderEdge">
        <TextBlock Text="InnerBorderEdge"
                   HorizontalAlignment="Center"/>
    </Border>

    <Border Background="Gray"
           Width="200" Height="200"
           BoxShadow="0 16 16 0 #35000000"
           BackgroundSizing="OuterBorderEdge">
        <TextBlock Text="OuterBorderEdge"
                   HorizontalAlignment="Center"/>
    </Border>
    
</StackPanel>

Expected behavior

No response

Avalonia version

11.1-beta1

OS

Windows

Additional context

No response

[amwx]

Related: #13251 Now that we have BackgroundSizing which draws via geometry (if not wanting the Skia default), it might be time to allow shadows on things that aren't just Rectangles

[robloo]

Hmm, I suspect there is a bit more going on here. I don't recall running across the box shadow code for the BackgroundSizing work. That said, I suspect the box shadow only ever worked with the simple rendering path.

[maxkatz6]

I suspect the box shadow only ever worked with the simple rendering path.

I am pretty sure that's the case.

Effects="drop-shadow(5 5 0 Green)" should still work with complex geometry. And we might be able to convert box shadow to drop shadow for complex borders.

[amwx]

Oh, I didn't know about the Effects API which is what along the lines of what I was thinking was needed. That works nicely.