Unexpected visual behavior of clip

[xlxdd]

Describe the bug

When using Clip to constrain the visible area of a control, the result does not match the expected behavior.
It seems the outer pixels expected to be cut come in.
It's hard for me to describe,but I think you can understand if you see the picture.

To Reproduce

Here is a simple way to Reproduce it.

<StackPanel Orientation="Horizontal" Spacing="10">
            <Border Width="100" Height="100" Background="Black">
                                <Border Width="100" Height="100" CornerRadius="50" Background="White"/>
            </Border>
            <Border Width="100" Height="100" Background="Black">
                <Border.Clip>
                    <EllipseGeometry Center="50,50" RadiusX="50" RadiusY="50"/>
                </Border.Clip>
                <Border Width="100" Height="100" CornerRadius="50" Background="White"/>
            </Border>
            <Border Width="100" Height="100" Background="Black">
                <Border.Clip>
                    <EllipseGeometry Center="50,50" RadiusX="30" RadiusY="30"/>
                </Border.Clip>
                <Border Width="100" Height="100" CornerRadius="50" Background="White"/>
            </Border>
</StackPanel>

And what it looks like:

Expected behavior

No response

Avalonia version

11.1.3

OS

Windows

Additional context

No response

[robloo]

Yea, this issue shows up all over the place in subtle ways. Usually with anti-aliasing and corner radius, etc. It's an issue with Skia itself as far as I know and there isn't a generalized solution for all cases yet.

You will probably have to find something that works for your case (usually making the clip 1 pixel larger or something).

Also see:

• Artifacts when using BoxShadow and CornerRadius with positive spreadradius #16010
• Slider with custom style leaves spots outside of its bounds #14270
• https://issues.skia.org/issues/327877721