/// <summary>
/// Helper method used by the BringToFront and SendToBack methods.
/// </summary>
/// <param name="element">
/// The element to bring to the front or send to the back.
/// </param>
/// <param name="bringToFront">
/// Pass true if calling from BringToFront, else false.
/// </param>
private void UpdateZOrder(UIElement element, bool bringToFront)
{
#region Safety Check
if (element == null)
{
throw new ArgumentNullException("element");
}
if (!base.Children.Contains(element))
{
throw new ArgumentException("Must be a child element of the Canvas.", "element");
}
#endregion // Safety Check
#region Calculate Z-Indexes And Offset
// Determine the Z-Index for the target UIElement.
int elementNewZIndex = -1;
if (bringToFront)
{
foreach (UIElement elem in base.Children)
{
if (elem.Visibility != Visibility.Collapsed)
{
++elementNewZIndex;
}
}
}
else
{
elementNewZIndex = 0;
}
// Determine if the other UIElements' Z-Index
// should be raised or lowered by one.
int offset = (elementNewZIndex == 0) ? +1 : -1;
int elementCurrentZIndex = Canvas.GetZIndex(element);
#endregion // Calculate Z-Indici And Offset
#region Update Z-Indexes
// Update the Z-Index of every UIElement in the Canvas.
foreach (UIElement childElement in base.Children)
{
if (childElement == element)
{
Canvas.SetZIndex(element, elementNewZIndex);
}
else
{
int zIndex = Canvas.GetZIndex(childElement);
// Only modify the z-index of an element if it is
// in between the target element's old and new z-index.
if (bringToFront && elementCurrentZIndex < zIndex || !bringToFront && zIndex < elementCurrentZIndex)
{
Canvas.SetZIndex(childElement, zIndex + offset);
}
}
}
#endregion // Update Z-Indexes
}
