Comment conserver l'état de contrôle dans un onglet dans un TabControl

j'ai obtenu résoudre avec ce conseil WPF TabControl: Turning Off Tab Virtualization à http://www.codeproject.com/Articles/460989/WPF-TabControl-Turning-Off-Tab-Virtualization il s'agit d'une classe de contenu Tabacal avec la propriété IsCached.

j'ai eu le même problème et j'ai trouvé une bonne solution vous pouvez l'utiliser comme une normale TabControl autant que je l'ai testé. Dans le cas où il est important pour vous ici la licence actuelle

ici le Code sur le cas où le lien descend:

using System;
using System.Collections.Specialized;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;

namespace CefSharp.Wpf.Example.Controls
{
    /// <summary>
    /// Extended TabControl which saves the displayed item so you don't get the performance hit of
    /// unloading and reloading the VisualTree when switching tabs
    /// </summary>
    /// <remarks>
    /// Based on example from http://stackoverflow.com/a/9802346, which in turn is based on
    /// http://www.pluralsight-training.net/community/blogs/eburke/archive/2009/04/30/keeping-the-wpf-tab-control-from-destroying-its-children.aspx
    /// with some modifications so it reuses a TabItem's ContentPresenter when doing drag/drop operations
    /// </remarks>
    [TemplatePart(Name = "PART_ItemsHolder", Type = typeof(Panel))]
    public class NonReloadingTabControl : TabControl
    {
        private Panel itemsHolderPanel;

        public NonReloadingTabControl()
        {
            // This is necessary so that we get the initial databound selected item
            ItemContainerGenerator.StatusChanged += ItemContainerGeneratorStatusChanged;
        }

        /// <summary>
        /// If containers are done, generate the selected item
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
        private void ItemContainerGeneratorStatusChanged(object sender, EventArgs e)
        {
            if (ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
            {
                ItemContainerGenerator.StatusChanged -= ItemContainerGeneratorStatusChanged;
                UpdateSelectedItem();
            }
        }

        /// <summary>
        /// Get the ItemsHolder and generate any children
        /// </summary>
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            itemsHolderPanel = GetTemplateChild("PART_ItemsHolder") as Panel;
            UpdateSelectedItem();
        }

        /// <summary>
        /// When the items change we remove any generated panel children and add any new ones as necessary
        /// </summary>
        /// <param name="e">The <see cref="NotifyCollectionChangedEventArgs"/> instance containing the event data.</param>
        protected override void OnItemsChanged(NotifyCollectionChangedEventArgs e)
        {
            base.OnItemsChanged(e);

            if (itemsHolderPanel == null)
                return;

            switch (e.Action)
            {
                case NotifyCollectionChangedAction.Reset:
                itemsHolderPanel.Children.Clear();
                break;

                case NotifyCollectionChangedAction.Add:
                case NotifyCollectionChangedAction.Remove:
                if (e.OldItems != null)
                {
                    foreach (var item in e.OldItems)
                    {
                        var cp = FindChildContentPresenter(item);
                        if (cp != null)
                            itemsHolderPanel.Children.Remove(cp);
                    }
                }

                // Don't do anything with new items because we don't want to
                // create visuals that aren't being shown

                UpdateSelectedItem();
                break;

                case NotifyCollectionChangedAction.Replace:
                throw new NotImplementedException("Replace not implemented yet");
            }
        }

        protected override void OnSelectionChanged(SelectionChangedEventArgs e)
        {
            base.OnSelectionChanged(e);
            UpdateSelectedItem();
        }

        private void UpdateSelectedItem()
        {
            if (itemsHolderPanel == null)
                return;

            // Generate a ContentPresenter if necessary
            var item = GetSelectedTabItem();
            if (item != null)
                CreateChildContentPresenter(item);

            // show the right child
            foreach (ContentPresenter child in itemsHolderPanel.Children)
                child.Visibility = ((child.Tag as TabItem).IsSelected) ? Visibility.Visible : Visibility.Collapsed;
        }

        private ContentPresenter CreateChildContentPresenter(object item)
        {
            if (item == null)
                return null;

            var cp = FindChildContentPresenter(item);

            if (cp != null)
                return cp;

            var tabItem = item as TabItem;
            cp = new ContentPresenter
            {
                Content = (tabItem != null) ? tabItem.Content : item,
                ContentTemplate = this.SelectedContentTemplate,
                ContentTemplateSelector = this.SelectedContentTemplateSelector,
                ContentStringFormat = this.SelectedContentStringFormat,
                Visibility = Visibility.Collapsed,
                Tag = tabItem ?? (this.ItemContainerGenerator.ContainerFromItem(item))
            };
            itemsHolderPanel.Children.Add(cp);
            return cp;
        }

        private ContentPresenter FindChildContentPresenter(object data)
        {
            if (data is TabItem)
                data = (data as TabItem).Content;

            if (data == null)
                return null;

            if (itemsHolderPanel == null)
                return null;

            foreach (ContentPresenter cp in itemsHolderPanel.Children)
            {
                if (cp.Content == data)
                    return cp;
            }

            return null;
        }

        protected TabItem GetSelectedTabItem()
        {
            var selectedItem = SelectedItem;
            if (selectedItem == null)
                return null;

            var item = selectedItem as TabItem ?? ItemContainerGenerator.ContainerFromIndex(SelectedIndex) as TabItem;

            return item;
        }
    }
}

licence à L'Heure de la copie

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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

en utilisant L'idée de WAF je viens à cette solution simple qui semble résoudre le problème.

j'utilise le comportement D'interactivité, mais la même chose peut être faite avec la propriété attachée si la bibliothèque D'interactivité n'est pas référencée

/// <summary>
/// Wraps tab item contents in UserControl to prevent TabControl from re-using its content
/// </summary>
public class TabControlUcWrapperBehavior 
    : Behavior<UIElement>
{
    private TabControl AssociatedTabControl { get { return (TabControl) AssociatedObject; } }

    protected override void OnAttached()
    {
        ((INotifyCollectionChanged)AssociatedTabControl.Items).CollectionChanged += TabControlUcWrapperBehavior_CollectionChanged;
        base.OnAttached();
    }

    protected override void OnDetaching()
    {
        ((INotifyCollectionChanged)AssociatedTabControl.Items).CollectionChanged -= TabControlUcWrapperBehavior_CollectionChanged;
        base.OnDetaching();
    }

    void TabControlUcWrapperBehavior_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.Action != NotifyCollectionChangedAction.Add) 
            return;

        foreach (var newItem in e.NewItems)
        {
            var ti = AssociatedTabControl.ItemContainerGenerator.ContainerFromItem(newItem) as TabItem;

            if (ti != null && !(ti.Content is UserControl)) 
                ti.Content = new UserControl { Content = ti.Content };
        }
    }
}

et usage

<TabControl ItemsSource="...">
    <i:Interaction.Behaviors>
        <controls:TabControlUcWrapperBehavior/>
    </i:Interaction.Behaviors>
</TabControl>

basé sur la réponse de @Arsen ci-dessus, voici un autre comportement, que:

1. N'a pas besoin de références supplémentaires. (sauf si vous mettez le code dans une bibliothèque externe)
2. il n'utilise pas de classe de base.
3. il gère à la fois réinitialiser et ajouter des changements de collecte.

pour l'utiliser

Déclarer l'espace de noms dans le code xaml:

<ResourceDictionary
    ...
    xmlns:behaviors="clr-namespace:My.Behaviors;assembly=My.Wpf.Assembly"
    ...
    >

mettre à jour le style:

<Style TargetType="TabControl" x:Key="TabControl">
    ...
    <Setter Property="behaviors:TabControlBehavior.DoNotCacheControls" Value="True" />
    ...
</Style>

Ou mettre à jour le TabControl directement:

<TabControl behaviors:TabControlBehavior.DoNotCacheControls="True" ItemsSource="{Binding Tabs}" SelectedItem="{Binding SelectedTab}">

Et voici le code pour le comportement:

using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Windows;
using System.Windows.Controls;

namespace My.Behaviors
{
    /// <summary>
    /// Wraps tab item contents in UserControl to prevent TabControl from re-using its content
    /// </summary>
    public class TabControlBehavior
    {
        private static readonly HashSet<TabControl> _tabControls = new HashSet<TabControl>();
        private static readonly Dictionary<ItemCollection, TabControl> _tabControlItemCollections = new Dictionary<ItemCollection, TabControl>();

        public static bool GetDoNotCacheControls(TabControl tabControl)
        {
            return (bool)tabControl.GetValue(DoNotCacheControlsProperty);
        }

        public static void SetDoNotCacheControls(TabControl tabControl, bool value)
        {
            tabControl.SetValue(DoNotCacheControlsProperty, value);
        }

        public static readonly DependencyProperty DoNotCacheControlsProperty = DependencyProperty.RegisterAttached(
            "DoNotCacheControls",
            typeof(bool),
            typeof(TabControlBehavior),
            new UIPropertyMetadata(false, OnDoNotCacheControlsChanged));

        private static void OnDoNotCacheControlsChanged(
            DependencyObject depObj,
            DependencyPropertyChangedEventArgs e)
        {
            var tabControl = depObj as TabControl;
            if (null == tabControl)
                return;
            if (e.NewValue is bool == false)
                return;

            if ((bool)e.NewValue)
                Attach(tabControl);
            else
                Detach(tabControl);
        }

        private static void Attach(TabControl tabControl)
        {
            if (!_tabControls.Add(tabControl))
                return;
            _tabControlItemCollections.Add(tabControl.Items, tabControl);
            ((INotifyCollectionChanged)tabControl.Items).CollectionChanged += TabControlUcWrapperBehavior_CollectionChanged;
        }

        private static void Detach(TabControl tabControl)
        {
            if (!_tabControls.Remove(tabControl))
                return;
            _tabControlItemCollections.Remove(tabControl.Items);
            ((INotifyCollectionChanged)tabControl.Items).CollectionChanged -= TabControlUcWrapperBehavior_CollectionChanged;
        }

        private static void TabControlUcWrapperBehavior_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            var itemCollection = (ItemCollection)sender;
            var tabControl = _tabControlItemCollections[itemCollection];
            IList items;
            if (e.Action == NotifyCollectionChangedAction.Reset)
            {   /* our ObservableArray<T> swops out the whole collection */
                items = (ItemCollection)sender;
            }
            else
            {
                if (e.Action != NotifyCollectionChangedAction.Add)
                    return;

                items = e.NewItems;
            }

            foreach (var newItem in items)
            {
                var ti = tabControl.ItemContainerGenerator.ContainerFromItem(newItem) as TabItem;
                if (ti != null)
                {
                    var userControl = ti.Content as UserControl;
                    if (null == userControl)
                        ti.Content = new UserControl { Content = ti.Content };
                }
            }
        }
    }
}

j'ai posté une réponse à une question similaire. Dans mon cas la création manuelle des TabItems ont résolu le problème de la création de la vue encore et encore. Vérifier ici