Silverlight ScrollViewer not updating after zoom - zooming

Question

I have a Silverlight grid with a bunch of content in it (rectangles, textBlocks, etc.) which represents content in a room. Because it gets pretty complex, I decided I needed an ability to "zoom-in" on the grid. I found some good code to do that, but the problem is that after zooming the grids associated ScrollViewer doesn't scroll the full distance down or to the right. How can I force it to update so that I can scroll to the bottom and all the way to the right?
If it helps, here's the code to permit zooming of my Grid:
var style = new Style(typeof(Grid));
var scale = new ScaleTransform();
scale.CenterX = .5;
scale.CenterY =.5;
scale.ScaleX = Scale;
scale.ScaleY = Scale;
var rs = new Setter();
rs.Property = DataGridCell.RenderTransformProperty;
rs.Value = scale;
style.Setters.Add(rs);
OtdrPatchLocationGrid.Style = style;
and here is the XAML that shows the grid and the scroll viewer
<ScrollViewer Name="scViewer" Grid.Row="1" Visibility="Visible" VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Visible">
<Grid x:Name="OtdrPatchLocationGrid" MinHeight="350" VerticalAlignment="Stretch" Background="Yellow" Grid.Row="1" Grid.Column="0" Margin="0" MouseDown="OtdrRackViewer_MouseDown">
</Grid>
</ScrollViewer>

Answer 1

I'm working on the same issue now,
the ScrollViewer is affected only by the change in Width or Height,
so to fix the problem, you have to do as the following:
suppose we got the Grid or Canvas named (ZoomCanvas)
in the code behind:
double initialCanvasHeight;
double initialCanvasWidth;
public void MainPage() //As the Constructor
{
initialCanvasHeight = ZoomCanvas.Height;
initialCanvasWidth = ZoomCanvas.Width;
}
ZoomCanvas_MouseWheel(object sender, MouseWheelEventArgs e)
{
/*Assuming you have the scaling code here and the object CanvasScale is used to scale the canvas*/
foreach (var node in ZoomCanvas)
{
var nodeTop = Canvas.GetTop(node);
var nodeLeft = Canvas.GetLeft(node);
if(mostTopValue < nodeTop)
mostTopValue = nodeTop;
if(mostLeftValue < nodeLeft)
mostLeftValue = nodeLeft;
var desiredHeight = (mostTopValue + NodeHeight)*canvasScale.ScaleY;
var desiredWidth = (mostLeftValue + NodeWidth) * canvasScale.ScaleX;
if (desiredHeight > canvasInitialHeight)
{
while (heightToIncrease < desiredHeight)
heightToIncrease += 10;
ZoomCanvas.Height = heightToIncrease;
}
else
while (ZoomCanvas.Height > canvasInitialHeight)
ZoomCanvas.Height -= 10;
if (desiredWidth > canvasInitialWidth)
{
while (widthToIncrease < desiredWidth)
widthToIncrease += 10;
ZoomCanvas.Width = widthToIncrease;
}
else while (ZoomCanvas.Height > canvasInitialHeight)
ZoomCanvas.Width -= 10;
}
scrollViewer.UpdateLayout();
}