DXTabControl.SelectionChanging Event

Occurs before the selected tab item is changed.

Namespace: DevExpress.Xpf.Core

Assembly: DevExpress.Xpf.Core.v23.2.dll

NuGet Package: DevExpress.Wpf.Core

Declaration

C#

public event TabControlSelectionChangingEventHandler SelectionChanging

VB.NET

Public Event SelectionChanging As TabControlSelectionChangingEventHandler

Event Data

The SelectionChanging event's data class is TabControlSelectionChangingEventArgs. The following properties provide information specific to this event:

Property	Description
Cancel	Gets or sets a value indicating whether the event should be canceled. Inherited from CancelEventArgs.
NewSelectedIndex	Gets the index of the tab item that is about to be selected.
NewSelectedItem	Gets the tab item to be selected.
OldSelectedIndex	Gets the index of the currently selected tab item.
OldSelectedItem	Gets the currently selected tab item.

Remarks

Handle the SelectionChanging event to prevent selecting a tab item. To do this, set the event parameter’s TabControlSelectionChangingEventArgs.Cancel property to true.

To obtain which tab item is being selected, use the event parameter’s TabControlSelectionChangingEventArgs.NewSelectedIndex property. The index of the previously selected tab item is returned by the event parameter’s TabControlSelectionChangedEventArgs.OldSelectedIndex property. Use the DXTabControl.GetTabItem method to obtain a tab item by its index.

After a tab item has been selected, the DXTabControl.SelectionChanged event is fired.

Example

The following example handles the DXTabControl.SelectionChanging event and does not allow users to select tab items if their IsUrgent property is set to false.

MainWindow.xaml

<Window xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        x:Class="DXTabControl_RestrictingSelection.MainWindow" 
        Title="MainWindow" Height="350" Width="525">
    <Grid x:Name="LayoutRoot" Loaded="LayoutRoot_Loaded">
        <dx:DXTabControl x:Name="tabControl" Height="140" Width="300" 
                         SelectionChanging="tabControl_SelectionChanging">
            <dx:DXTabControl.ItemHeaderTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Path=ProductName}" />
                </DataTemplate>
            </dx:DXTabControl.ItemHeaderTemplate>
            <dx:DXTabControl.ItemTemplate>
                <DataTemplate>
                    <StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="ID = " />
                            <TextBlock Text="{Binding Path=ID}" Foreground="Blue" />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="Price = " />
                            <TextBlock Text="{Binding Path=Price}" Foreground="Blue" />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="Discount = " />
                            <TextBlock Text="{Binding Path=Discount}" Foreground="Blue" />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="Order Date = " />
                            <TextBlock Text="{Binding Path=OrderDate}" Foreground="Blue" />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="Status = " />
                            <TextBlock Text="{Binding Path=Status}" Foreground="Blue" />
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="Urgent = " />
                            <TextBlock Text="{Binding Path=IsUrgent}" Foreground="Blue" />
                        </StackPanel>
                    </StackPanel>
                </DataTemplate>
            </dx:DXTabControl.ItemTemplate>
            <dx:DXTabControl.View>
                <dx:TabControlScrollView ShowHeaderMenu="True" />
            </dx:DXTabControl.View>
        </dx:DXTabControl>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Windows;
using DevExpress.Xpf.Core;
using DXExample.DemoData;

namespace DXTabControl_RestrictingSelection {
    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();
        }
        private void LayoutRoot_Loaded(object sender, RoutedEventArgs e) {
            tabControl.ItemsSource = Invoice.GetData();
        }
        private void tabControl_SelectionChanging(object sender,
            TabControlSelectionChangingEventArgs e) {
            if (!((Invoice)tabControl.Items[e.NewSelectedIndex]).IsUrgent)
                e.Cancel = true;
        }
    }
}

MainWindow.xaml.vb

Imports System.Windows
Imports DevExpress.Xpf.Core
Imports DXExample.DemoData

Namespace DXTabControl_RestrictingSelection
    Partial Public Class MainWindow
        Inherits Window

        Public Sub New()
            InitializeComponent()
        End Sub
        Private Sub LayoutRoot_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
            tabControl.ItemsSource = Invoice.GetData()
        End Sub
        Private Sub tabControl_SelectionChanging(ByVal sender As Object, ByVal e As TabControlSelectionChangingEventArgs)
            If Not CType(tabControl.Items(e.NewSelectedIndex), Invoice).IsUrgent Then
                e.Cancel = True
            End If
        End Sub
    End Class
End Namespace

DataSource.cs

using System;
using System.Collections.Generic;

namespace DXExample.DemoData {
    public enum InvoiceStatus { Ordered, Payed, Shipped, Delivered, Invalidated }
    public class Invoice {
        public int ID { get; set; }
        public string ProductName { get; set; }
        public double Price { get; set; }
        public DateTime OrderDate { get; set; }
        public double Discount { get; set; }
        public bool IsUrgent { get; set; }
        public InvoiceStatus Status { get; set; }
        static public List<Invoice> GetData() {
            List<Invoice> data = new List<Invoice>();

            data.Add(new Invoice() { ID = 0, ProductName = "Tofu", IsUrgent = false,
                Price = 235.54, Discount = 9.4, Status = InvoiceStatus.Invalidated,
                OrderDate = new DateTime(2009, 3, 12) });
            data.Add(new Invoice() { ID = 1, ProductName = "Ravioli Angelo", IsUrgent = true,
                Price = 178.45, Discount = 6.1, Status = InvoiceStatus.Delivered,
                OrderDate = new DateTime(2009, 2, 9) });
            data.Add(new Invoice() { ID = 2, ProductName = "Geitost", IsUrgent = false,
                Price = 89.98, Discount = 5.4, Status = InvoiceStatus.Payed,
                OrderDate = new DateTime(2009, 4, 1) });
            data.Add(new Invoice() { ID = 3, ProductName = "Chang", IsUrgent = true,
                Price = 189.33, Discount = 18.2, Status = InvoiceStatus.Shipped,
                OrderDate = new DateTime(2009, 5, 23) });
            data.Add(new Invoice() { ID = 4, ProductName = "Inlagd Sill", IsUrgent = false, 
                Price = 509.10, Discount = 22.2, Status = InvoiceStatus.Ordered,
                OrderDate = new DateTime(2009, 6, 30) });
            data.Add(new Invoice() { ID = 5, ProductName = "Alice Mutton", IsUrgent = true,
                Price = 791.18, Discount = 24.4, Status = InvoiceStatus.Invalidated,
                OrderDate = new DateTime(2009, 5, 7) });

            return data;
        }
    }
}

DataSource.vb

Imports System
Imports System.Collections.Generic

Namespace DXExample.DemoData
    Public Enum InvoiceStatus
        Ordered
        Payed
        Shipped
        Delivered
        Invalidated
    End Enum
    Public Class Invoice
        Public Property ID() As Integer
        Public Property ProductName() As String
        Public Property Price() As Double
        Public Property OrderDate() As Date
        Public Property Discount() As Double
        Public Property IsUrgent() As Boolean
        Public Property Status() As InvoiceStatus
        Public Shared Function GetData() As List(Of Invoice)
            Dim data As New List(Of Invoice)()

            data.Add(New Invoice() With {.ID = 0, .ProductName = "Tofu", .IsUrgent = False, .Price = 235.54, .Discount = 9.4, .Status = InvoiceStatus.Invalidated, .OrderDate = New Date(2009, 3, 12)})
            data.Add(New Invoice() With {.ID = 1, .ProductName = "Ravioli Angelo", .IsUrgent = True, .Price = 178.45, .Discount = 6.1, .Status = InvoiceStatus.Delivered, .OrderDate = New Date(2009, 2, 9)})
            data.Add(New Invoice() With {.ID = 2, .ProductName = "Geitost", .IsUrgent = False, .Price = 89.98, .Discount = 5.4, .Status = InvoiceStatus.Payed, .OrderDate = New Date(2009, 4, 1)})
            data.Add(New Invoice() With {.ID = 3, .ProductName = "Chang", .IsUrgent = True, .Price = 189.33, .Discount = 18.2, .Status = InvoiceStatus.Shipped, .OrderDate = New Date(2009, 5, 23)})
            data.Add(New Invoice() With {.ID = 4, .ProductName = "Inlagd Sill", .IsUrgent = False, .Price = 509.10, .Discount = 22.2, .Status = InvoiceStatus.Ordered, .OrderDate = New Date(2009, 6, 30)})
            data.Add(New Invoice() With {.ID = 5, .ProductName = "Alice Mutton", .IsUrgent = True, .Price = 791.18, .Discount = 24.4, .Status = InvoiceStatus.Invalidated, .OrderDate = New Date(2009, 5, 7)})

            Return data
        End Function
    End Class
End Namespace