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Comment : créer un élément Panel personnalisé

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Exemple

Cet exemple montre comment remplacer le comportement de disposition par défaut de l’élément Panel et créer des éléments de disposition personnalisés dérivés de Panel.

L’exemple définit un élément personnalisé Panel simple appelé PlotPanel, qui positionne les éléments enfants en fonction de deux coordonnées x et y codées en dur. Dans cet exemple, x et y sont tous les deux définis 50sur ; par conséquent, tous les éléments enfants sont positionnés à cet emplacement sur les axes x et y.

Pour implémenter des comportements personnalisésPanel, l’exemple utilise les méthodes et ArrangeOverride les MeasureOverride méthodes. Chaque méthode retourne les Size données nécessaires à la position et au rendu des éléments enfants.

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

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