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Vorgehensweise: Anwenden des PropertyNameChanged-Musters

  • Artikel

Im folgenden Codebeispiel wird veranschaulicht, wie das PropertyNameGeändertes Muster auf ein benutzerdefiniertes Steuerelement angewendet wird. Wenden Sie dieses Muster an, wenn Sie benutzerdefinierte Steuerelemente implementieren, die mit dem Windows Forms-Datenbindungsmodul verwendet werden.

Beispiel

// This class implements a simple user control
// that demonstrates how to apply the propertyNameChanged pattern.
[ComplexBindingProperties("DataSource", "DataMember")]
public class CustomerControl : UserControl
{
    private DataGridView dataGridView1;
    private Label label1;
    private DateTime lastUpdate = DateTime.Now;

    public EventHandler DataSourceChanged;

    public object DataSource
    {
        get
        {
            return this.dataGridView1.DataSource;
        }
        set
        {
            if (DataSource != value)
            {
                this.dataGridView1.DataSource = value;
                OnDataSourceChanged();
            }
        }
    }

    public string DataMember
    {
        get { return this.dataGridView1.DataMember; }

        set { this.dataGridView1.DataMember = value; }
    }

    private void OnDataSourceChanged()
    {
        if (DataSourceChanged != null)
        {
            DataSourceChanged(this, new EventArgs());
        }
    }

    public CustomerControl()
    {
        this.dataGridView1 = new System.Windows.Forms.DataGridView();
        this.label1 = new System.Windows.Forms.Label();
        this.dataGridView1.ColumnHeadersHeightSizeMode =
            System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
        this.dataGridView1.ImeMode = System.Windows.Forms.ImeMode.Disable;
        this.dataGridView1.Location = new System.Drawing.Point(19, 55);
        this.dataGridView1.Size = new System.Drawing.Size(350, 150);
        this.dataGridView1.TabIndex = 1;
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(19, 23);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(76, 13);
        this.label1.TabIndex = 2;
        this.label1.Text = "Customer List:";
        this.Controls.Add(this.label1);
        this.Controls.Add(this.dataGridView1);
        this.Size = new System.Drawing.Size(350, 216);
    }
}

' This class implements a simple user control 
' that demonstrates how to apply the propertyNameChanged pattern.
<ComplexBindingProperties("DataSource", "DataMember")>  _
Public Class CustomerControl
    Inherits UserControl
    Private dataGridView1 As DataGridView
    Private label1 As Label
    Private lastUpdate As DateTime = DateTime.Now
    
    Public DataSourceChanged As EventHandler
    
    
    Public Property DataSource() As Object 
        Get
            Return Me.dataGridView1.DataSource
        End Get
        Set
            If DataSource IsNot Value Then
                Me.dataGridView1.DataSource = Value
                OnDataSourceChanged()
            End If
        End Set
    End Property
    
    
    Public Property DataMember() As String 
        Get
            Return Me.dataGridView1.DataMember
        End Get 
        Set
            Me.dataGridView1.DataMember = value
        End Set 
    End Property
    
    
    Private Sub OnDataSourceChanged() 
        If (DataSourceChanged IsNot Nothing) Then
            DataSourceChanged(Me, New EventArgs())
        End If
    
    End Sub

    
    Public Sub New() 
        Me.dataGridView1 = New System.Windows.Forms.DataGridView()
        Me.label1 = New System.Windows.Forms.Label()
        Me.dataGridView1.ColumnHeadersHeightSizeMode = _
           System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize
        Me.dataGridView1.ImeMode = System.Windows.Forms.ImeMode.Disable
        Me.dataGridView1.Location = New System.Drawing.Point(19, 55)
        Me.dataGridView1.Size = New System.Drawing.Size(350, 150)
        Me.dataGridView1.TabIndex = 1
        Me.label1.AutoSize = True
        Me.label1.Location = New System.Drawing.Point(19, 23)
        Me.label1.Name = "label1"
        Me.label1.Size = New System.Drawing.Size(76, 13)
        Me.label1.TabIndex = 2
        Me.label1.Text = "Customer List:"
        Me.Controls.Add(Me.label1)
        Me.Controls.Add(Me.dataGridView1)
        Me.Size = New System.Drawing.Size(350, 216)
    End Sub
End Class

Code kompilieren

So kompilieren Sie das vorherige Codebeispiel:

  • Fügen Sie den Code in eine leere Codedatei ein. Sie müssen das benutzerdefinierte Steuerelement in einem Windows-Formular verwenden, das eine Main-Methode enthält.

Siehe auch