/// <summary>
/// Notification that is called by Measure of a child when
/// it ends up with different desired size for the child.
/// </summary>
/// <remarks>
/// Default implementation simply calls invalidateMeasure(), assuming that layout of a
/// parent should be updated after child changed its size.<para/>
/// Finer point: this method can only be called in the scenario when the system calls Measure on a child,
/// not when parent calls it since if parent calls it, it means parent has dirty layout and is recalculating already.
/// </remarks>
protected virtual void OnChildDesiredSizeChanged(UIElement child)
{
if (IsMeasureValid)
InvalidateMeasure();
}
/// <summary>
/// OnChildrenChanged is called when the UIElementCollection of the UIElement is edited.
/// </summary>
protected internal virtual void OnChildrenChanged(UIElement added, UIElement removed, int indexAffected)
{
//Child visibility can't change if parent isn't visible
if ((this._flags & Flags.IsVisibleCache) != 0)
{
if (removed != null && removed._visibility == Visibility.Visible)
{
removed._flags &= ~Flags.IsVisibleCache;
removed.OnIsVisibleChanged(true);
}
if (added != null && added._visibility == Visibility.Visible)
{
added._flags |= Flags.IsVisibleCache;
added.OnIsVisibleChanged(false);
}
}
}
/// <summary>
/// Recursively resets IsLayoutSuspended flag on all visuals of the whole v's sub tree.
/// For UIElements also re-inserts the UIElement into Measure and / or Arrange update queues
/// if necessary.
/// </summary>
internal static void PropagateResumeLayout(UIElement e)
{
if ((e._flags & Flags.IsLayoutSuspended) != 0)
{
e._flags &= ~Flags.IsLayoutSuspended;
Debug.Assert((e._flags & (Flags.MeasureInProgress | Flags.ArrangeInProgress)) == 0);
bool requireMeasureUpdate = ((e._flags & Flags.InvalidMeasure) != 0) && ((e._flags & Flags.NeverMeasured) == 0);
bool requireArrangeUpdate = ((e._flags & Flags.InvalidArrange) != 0) && ((e._flags & Flags.NeverArranged) == 0);
LayoutManager layoutManager = (requireMeasureUpdate || requireArrangeUpdate) ? LayoutManager.From(e.Dispatcher) : null;
if (requireMeasureUpdate)
{
layoutManager.MeasureQueue.Add(e);
}
if (requireArrangeUpdate)
{
layoutManager.ArrangeQueue.Add(e);
}
UIElementCollection children = e._logicalChildren;
if (children != null)
{
int count = children.Count;
for (int i = 0; i < count; i++)
{
UIElement child = children[i];
if (child != null)
{
PropagateResumeLayout(child);
}
}
}
}
}
/// <summary>
/// Recursively propagates IsLayoutSuspended flag down to the whole v's sub tree.
/// </summary>
internal static void PropagateSuspendLayout(UIElement v)
{
if ((v._flags & Flags.IsLayoutSuspended) == 0)
{
v._flags |= Flags.IsLayoutSuspended;
UIElementCollection children = v._logicalChildren;
if (children != null)
{
int count = children.Count;
for (int i = 0; i < count; i++)
{
UIElement child = children[i];
if (child != null)
PropagateSuspendLayout(child);
}
}
}
}
internal static void PropagateFlags(UIElement e, Flags flags)
{
while ((e != null) && ((e._flags & flags) == 0))
{
e._flags |= flags;
if ((e._flags & Flags.ShouldPostRender) != 0)
{
MediaContext.From(e.Dispatcher).PostRender();
}
e = e._parent;
}
}