wpf讓圖片自適應容器大小，而且又不會拉升變形

        <Grid Grid.Column="3"
              Margin="0,4,0,0"
              Background="Black">
            <Viewbox>
                <Image Width="{Binding RelativeSource={RelativeSource Self}, Path=Source.PixelWidth}"
                       Height="{Binding RelativeSource={RelativeSource Self}, Path=Source.PixelHeight}"
                       Source="{Binding CtrlImage, IsAsync=True}"
                       Stretch="None" />
            </Viewbox>
        </Grid>