How to: Create a Custom Panel Element

Example

This example shows how to override the default layout behavior of the Panel element and create custom layout elements that are derived from Panel.

The example defines a simple custom Panel element called PlotPanel, which positions child elements according to two hard-coded x- and y-coordinates. In this example, x and y are both set to 50; therefore, all child elements are positioned at that location on the x and y axes.

To implement custom Panel behaviors, the example uses the MeasureOverride and ArrangeOverride methods. Each method returns the Size data that is necessary to position and render child elements.

public: 
 ref class PlotPanel : Panel {

 public: 
 PlotPanel () {};

 protected: 
 // Override the default Measure method of Panel
 virtual Size MeasureOverride(Size availableSize) override
 {
 Size^ panelDesiredSize = gcnew Size();

 // In our example, we just have one child. 
 // Report that our panel requires just the size of its only child.
 for each (UIElement^ child in InternalChildren)
 {
 child->Measure(availableSize);
 panelDesiredSize = child->DesiredSize;
 }
 return *panelDesiredSize ;
 }

 protected: 
 virtual System::Windows::Size ArrangeOverride (Size finalSize) override 
 {
 for each (UIElement^ child in InternalChildren)
 {
 double x = 50;
 double y = 50;
 child->Arrange(Rect(Point(x, y), child->DesiredSize));
 }
 return finalSize;
 };
 };

public class PlotPanel : Panel
{
 // Default public constructor
 public PlotPanel()
 : base()
 {
 }

 // Override the default Measure method of Panel
 protected override Size MeasureOverride(Size availableSize)
 {
 Size panelDesiredSize = new Size();

 // In our example, we just have one child.
 // Report that our panel requires just the size of its only child.
 foreach (UIElement child in InternalChildren)
 {
 child.Measure(availableSize);
 panelDesiredSize = child.DesiredSize;
 }

 return panelDesiredSize ;
 }
 protected override Size ArrangeOverride(Size finalSize)
 {
 foreach (UIElement child in InternalChildren)
 {
 double x = 50;
 double y = 50;

 child.Arrange(new Rect(new Point(x, y), child.DesiredSize));
 }
 return finalSize; // Returns the final Arranged size
 }
}

Public Class PlotPanel
 Inherits Panel
 'Override the default Measure method of Panel.

 Protected Overrides Function MeasureOverride(ByVal availableSize As System.Windows.Size) As System.Windows.Size
 Dim panelDesiredSize As Size = New Size()
 ' In our example, we just have one child. 
 ' Report that our panel requires just the size of its only child.
 For Each child As UIElement In InternalChildren
 child.Measure(availableSize)
 panelDesiredSize = child.DesiredSize
 Next
 Return panelDesiredSize
 End Function
 Protected Overrides Function ArrangeOverride(ByVal finalSize As System.Windows.Size) As System.Windows.Size
 For Each child As UIElement In InternalChildren
 Dim x As Double = 50
 Dim y As Double = 50
 child.Arrange(New Rect(New System.Windows.Point(x, y), child.DesiredSize))
 Next
 Return finalSize
 End Function
End Class

See also

• Panel
• Panel