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.