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 childSize = availableSize;
for each (UIElement^ child in InternalChildren)
{
child->Measure(childSize);
}
return availableSize;
};
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 childSize = availableSize;
foreach (UIElement child in InternalChildren)
{
child.Measure(childSize);
}
return availableSize;
}
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 childSize As Size = CType(availableSize, Size)
For Each child As UIElement In InternalChildren
child.Measure(childSize)
Next
Return MyBase.MeasureOverride(availableSize)
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 MyBase.ArrangeOverride(finalSize)
End Function
End Class
For the complete sample, see Create a Simple Custom Panel Behavior Sample.