WinUI3 ImageEx Usage

<Style TargetType="local:ImageEx">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:ImageEx">
                <Grid>
                    <Image x:Name="PlaceholderImage" Visibility="Collapsed" Stretch="Uniform" />
                    <Image x:Name="MainImage" Visibility="Collapsed" Stretch="Uniform" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<local:ImageEx
    Grid.Column="0"
    PlaceholderSource="Assets/windows-icon.png"
    Source="{x:Bind Thumbnail, Mode=OneWay}"
    Width="200" />