downkyicore/DownKyi/CustomControl/AsyncImageLoader/Loaders/AdvancedImage.axaml

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:controls="clr-namespace:DownKyi.CustomControl.AsyncImageLoader.Loaders">
    <Design.PreviewWith>
        <controls:AdvancedImage />
    </Design.PreviewWith>

    <Style Selector="controls|AdvancedImage">
        <Setter Property="Template">
            <ControlTemplate>
                <Grid>
                    <!-- CurrentImage will be rendered with codebehind, just as it is done in the Image -->
                    <ProgressBar VerticalAlignment="Center" MinWidth="0" MaxWidth="100"
                                 IsIndeterminate="True"
                                 IsVisible="{TemplateBinding IsLoading}" />
                </Grid>
            </ControlTemplate>
        </Setter>
    </Style>
</Styles>