#1,192 – Calling Arrange on Child Elements

When you author a custom control that contains child elements, you should call the Arrange method of each child object within your ArrangeOverride method.

Below is an example, from a custom element with one child.  The parent control has a dependency property, ChildProperty, representing the single child element.

        protected override Size ArrangeOverride(Size finalSize)
            UIElement childElement = (UIElement)GetValue(ChildProperty);
            if (childElement != null)
                childElement.Arrange(new Rect(new Point(0.0, 0.0), finalSize));

            return finalSize;

Below is a second example, from a custom panel that renders a treemap-like element.  The ChildrenTreemapOrder method returns an enumerable of ChildAndRect objects.

protected override Size ArrangeOverride(Size finalSize)
    foreach (ChildAndRect child in ChildrenTreemapOrder(InternalChildren.Cast<UIElement>(), finalSize))

    return finalSize;

About Sean
Software developer in the Twin Cities area, passionate about software development and sailing.

3 Responses to #1,192 – Calling Arrange on Child Elements

  1. Pingback: Dew Drop – October 31, 2014 (#1889) | Morning Dew

  2. Kevin Donn says:

    Seems like you pasted in the same code snippet twice.

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