Wpf 缩放InkCanvas笔划以适合特定尺寸，以裁剪出未使用的空间

我正在尝试缩放InkCanvas的内容（笔划）以适合打印的固定页面大小。我想从InkCanvas中裁剪出所有周围的空白，并放大笔划以适应页面，同时保持纵横比

在标记下面的处理程序中，您可以看到我正在更改从800x300开始的网格的尺寸，并将其设置为425x550，即可打印页面大小的一半

标记：

 <Grid>

    <Button Height="100" Width="100" HorizontalAlignment="Left" PreviewMouseLeftButtonDown="Button_PreviewMouseLeftButtonDown_1" />

    <Grid Width="1200" Height="1400" Background="Aquamarine" HorizontalAlignment="Right" VerticalAlignment="Top">

        <Grid Background="Red" x:Name="grid" Width="800" Height="300">

            <Viewbox x:Name="vb"  Width="800" Height="300" Stretch="Fill" StretchDirection="Both">

                <InkCanvas Width="500" Height="500" Background="Transparent" IsEnabled="True"/>
            </Viewbox>

        </Grid >

    </Grid>
</Grid>

bool b = true;

private void Button_PreviewMouseLeftButtonDown_1(object sender, MouseButtonEventArgs e)
    {
        if (b)
            {
            //I toyed with using Uniform, UniformToFill, and Fill
            vb.Stretch = Stretch.Fill;
            grid.Width = 425;
            grid.Height = 550;

            //scale viewbox down until it fits horizontally
            var scaleX = grid.Width / vb.Width;
            vb.Width *= scaleX;
            vb.Height *= scaleX;

            //if constraining it to the width made it larger than it needed to be vertically, scale it down
            if (vb.Height > grid.Height)
            {
                var scaleY = grid.Height / vb.Height;
                vb.Width *= scaleY;
                vb.Height *= scaleY;
            }
            b = false;
        }
        else
        {
           //reset it back to what it was
            vb.Stretch = Stretch.Fill;
            grid.Width = 800;
            grid.Height = 300;
            vb.Width = grid.Width;
            vb.Height = grid.Height;
            b = true;
        }