/// <summary>
/// The desired size of a Track is the width (if vertically oriented) or height (if horizontally
/// oriented) of the Thumb.
///
/// When ViewportSize is NaN:
/// The thumb is measured to find the other dimension.
/// Otherwise:
/// Zero size is returned; Track can scale to any size along its children.
/// This means that it will occupy no space (and not display) unless made larger by a parent or specified size.
/// <seealso cref="FrameworkElement.MeasureOverride" />
/// </summary>
protected override Size MeasureOverride(Size availableSize)
{
Size desiredSize = new Size(0.0, 0.0);
// Only measure thumb
// Repeat buttons will be sized based on thumb
if (Thumb != null)
{
Thumb.Measure(availableSize);
desiredSize = Thumb.DesiredSize;
}
if (!double.IsNaN(ViewportSize))
{
// ScrollBar can shrink to 0 in the direction of scrolling
if (Orientation == Orientation.Vertical)
{
desiredSize.Height = 0.0;
}
else
{
desiredSize.Width = 0.0;
}
}
return(desiredSize);
}
protected override Size MeasureOverride(Size availableSize)
{
if (Thumb != null)
{
Thumb.Measure(availableSize);
return(GetMainSize(0).Combine(Thumb.DesiredSize));
}
return(Size.Zero);
}