Bonjour à tous,
Je sèche sur un truc qui aurait quand même pu être plus simple.
Contexte:
Une simple Listbox visualise les transmissions entrante et sortant sur le port COM.
Le souci, c'est que je souhaite respecter le pattern MVVM et a chaque ajout de texte j'ai un défilement automatique sur le dernier texte ajouté (ou arrêt du défilement si l'utilisateur souhaite vérifier manuellement les captures ,par exemple en cliquant sur une checkbox).
J'ai trouvé un code C# que j'ai adapté VB, mais s'il fonctionne bien au début ensuite lorsque la listbox ce rempli cela part en sucette avec des bon vers le bas puis vers le haut, c'est pas fluide (j’appelle sa des rebond). Pas clean donc. Et puis même sur le code C# je n'arrive pas a empêcher le défilement automatique à l'aide d'une Checkbox qui n'a du coup aucun effet.
Bizarrement sur cet exemple j'ai pas ce problème de rebond de l'autoscroll, pourtant le code est le même.
Exemple complet en C#:
Vue Model:
Classe LoggingListBox qui n'est pas de moi:
Code : Sélectionner tout - Visualiser dans une fenêtre à part
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57 using System; using System.Collections.Generic; using System.Collections.ObjectModel; using System.ComponentModel; using System.Linq; using System.Text; using System.Windows.Threading; namespace Test_Listbox_Autoscroll { class VueModele : INotifyPropertyChanged { DispatcherTimer Timer; ObservableCollection<String> _LST_ListBox1_Collection; String _LST_ListBox1_SelectedItem; int i; public VueModele() { LST_ListBox1_Collection = new ObservableCollection<string>(); Timer = new DispatcherTimer(); Timer.Interval = new TimeSpan(0, 0, 1); Timer.Tick += new EventHandler(Timer_Tick); Timer.Start(); } private void Timer_Tick(object sender, EventArgs e) { i += 1; LST_ListBox1_Collection.Add("Ligne " + i); } public ObservableCollection<String> LST_ListBox1_Collection { get { return _LST_ListBox1_Collection; } set { _LST_ListBox1_Collection = value; OnPropertyChanged("_LST_ListBox1_Collection"); } } public String LST_ListBox1_SelectedItem { get { return _LST_ListBox1_SelectedItem; } set { _LST_ListBox1_SelectedItem = value; OnPropertyChanged("LST_ListBox1_SelectedItem"); } } public event PropertyChangedEventHandler PropertyChanged; public void OnPropertyChanged(string Name) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(Name)); } } } }
Code : Sélectionner tout - Visualiser dans une fenêtre à part
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112 using System; using System.Collections.Generic; using System.Collections.Specialized; using System.ComponentModel; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; namespace Test_Listbox_Autoscroll { public class LoggingListBox : ListBox { ///<summary> ///Define the AutoScroll property. If enabled, causes the ListBox to scroll to ///the last item whenever a new item is added. ///</summary> public static readonly DependencyProperty AutoScrollProperty = DependencyProperty.Register( "AutoScroll", typeof(Boolean), typeof(LoggingListBox), new FrameworkPropertyMetadata( true, //Default value. FrameworkPropertyMetadataOptions.AffectsArrange | FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, AutoScroll_PropertyChanged)); /// <summary> /// Gets or sets whether or not the list should scroll to the last item /// when a new item is added. /// </summary> [Category("Common")] //Indicate where the property is located in VS designer. public bool AutoScroll { get { return (bool)GetValue(AutoScrollProperty); } set { SetValue(AutoScrollProperty, value); } } /// <summary> /// Event handler for when the AutoScroll property is changed. /// This delegates the call to SubscribeToAutoScroll_ItemsCollectionChanged(). /// </summary> /// <param name="d">The DependencyObject whose property was changed.</param> /// <param name="e">Change event args.</param> private static void AutoScroll_PropertyChanged( DependencyObject d, DependencyPropertyChangedEventArgs e) { SubscribeToAutoScroll_ItemsCollectionChanged( (LoggingListBox)d, (bool)e.NewValue); } /// <summary> /// Subscribes to the list items' collection changed event if AutoScroll is enabled. /// Otherwise, it unsubscribes from that event. /// For this to work, the underlying list must implement INotifyCollectionChanged. /// /// (This function was only creative for brevity) /// </summary> /// <param name="listBox">The list box containing the items collection.</param> /// <param name="subscribe">Subscribe to the collection changed event?</param> private static void SubscribeToAutoScroll_ItemsCollectionChanged( LoggingListBox listBox, bool subscribe) { INotifyCollectionChanged notifyCollection = listBox.Items.SourceCollection as INotifyCollectionChanged; if (notifyCollection != null) { if (subscribe) { //AutoScroll is turned on, subscribe to collection changed events. notifyCollection.CollectionChanged += listBox.AutoScroll_ItemsCollectionChanged; } else { //AutoScroll is turned off, unsubscribe from collection changed events. notifyCollection.CollectionChanged -= listBox.AutoScroll_ItemsCollectionChanged; } } } /// <summary> /// Event handler called only when the ItemCollection changes /// and if AutoScroll is enabled. /// </summary> /// <param name="sender">The ItemCollection.</param> /// <param name="e">Change event args.</param> private void AutoScroll_ItemsCollectionChanged( object sender, NotifyCollectionChangedEventArgs e) { if (e.Action == NotifyCollectionChangedAction.Add) { int count = Items.Count; ScrollIntoView(Items[count - 1]); } } /// <summary> /// Constructor a new LoggingListBox. /// </summary> public LoggingListBox() { //Subscribe to the AutoScroll property's items collection //changed handler by default if AutoScroll is enabled by default. SubscribeToAutoScroll_ItemsCollectionChanged( this, (bool)AutoScrollProperty.DefaultMetadata.DefaultValue); } } }
MainWindow XAML:
Code XAML : Sélectionner tout - Visualiser dans une fenêtre à part
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27 <Window x:Class="Test_Listbox_Autoscroll.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:Test_Listbox_Autoscroll" xmlns:tools="clr-namespace:Test_Listbox_Autoscroll" mc:Ignorable="d" Title="MainWindow" Width="800" SizeToContent =" WidthAndHeight"> <Grid> <StackPanel > <tools:LoggingListBox x:Name="Listbox1" Margin=" 10" Background="Bisque" Height="180" ItemsSource="{Binding LST_ListBox1_Collection}" SelectedItem="{Binding LST_ListBox1_SelectedItem}"/> <CheckBox x:Name="ChkAutoScroll" Margin="10" Content="Auto Scroll" Checked="ChkAutoScroll_Checked" Click="ChkAutoScroll_Click"/> </StackPanel> </Grid> </Window>
MainWindow Code:
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47 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace Test_Listbox_Autoscroll { /// <summary> /// Logique d'interaction pour MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); VueModele VM = new VueModele(); this.DataContext = VM; } private void ChkAutoScroll_Checked(object sender, RoutedEventArgs e) { } private void ChkAutoScroll_Click(object sender, RoutedEventArgs e) { if (ChkAutoScroll.IsChecked == true) { Listbox1.AutoScroll = true; } else { Listbox1.AutoScroll = false; } } } }
Voila le même code en VB:
Vue Model:
Code : Sélectionner tout - Visualiser dans une fenêtre à part
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52 Imports System.Collections.ObjectModel Imports System.ComponentModel Imports System.Windows.Threading Public Class VueModele Implements INotifyPropertyChanged Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged Public Sub OnPropertyChanged(propname As String) RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propname)) End Sub Private _LST_ListBox1_Collection As ObservableCollection(Of String) Private _LST_ListBox1_SelectedItem As Integer Private Timer As DispatcherTimer Private i As Integer Public Sub New() LST_ListBox1_Collection = New ObservableCollection(Of String) Timer = New DispatcherTimer Timer.Interval = New TimeSpan(0, 0, 1) AddHandler Timer.Tick, AddressOf Timer_Tick Timer.Start() End Sub Public Property LST_ListBox1_SelectedItem As Integer Get Return _LST_ListBox1_SelectedItem End Get Set(value As Integer) _LST_ListBox1_SelectedItem = value OnPropertyChanged("LST_ListBox1_SelectedItem") End Set End Property Public Property LST_ListBox1_Collection As ObservableCollection(Of String) Get Return _LST_ListBox1_Collection End Get Set(value As ObservableCollection(Of String)) _LST_ListBox1_Collection = value OnPropertyChanged("LST_ListBox1_Collection") End Set End Property Private Sub Timer_Tick() i += 1 LST_ListBox1_Collection.Add("Ligne " & CStr(i)) End Sub End Class
Classe LoggingListBox que j'ai converti:
MainWindow Xaml:
Code : Sélectionner tout - Visualiser dans une fenêtre à part
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55 Imports System.Collections.Specialized Imports System.ComponentModel Public Class LoggingListBox Inherits ListBox Public Shared ReadOnly AutoScrollProperty As DependencyProperty = DependencyProperty.Register("AutoScroll", GetType(Boolean), GetType(LoggingListBox), New FrameworkPropertyMetadata(True, FrameworkPropertyMetadataOptions.AffectsArrange Or FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, AddressOf AutoScroll_PropertyChanged)) <Category("Common")> Public Property AutoScroll() As Boolean Get Return DirectCast(GetValue(AutoScrollProperty), Boolean) End Get Set(ByVal value As Boolean) SetValue(AutoScrollProperty, value) End Set End Property Private Shared Sub AutoScroll_PropertyChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) SubscribeToAutoScroll_ItemsCollectionChanged(CType(d, LoggingListBox), DirectCast(e.NewValue, Boolean)) End Sub Private Shared Sub SubscribeToAutoScroll_ItemsCollectionChanged(ByVal listBox As LoggingListBox, ByVal subscribe As Boolean) Dim notifyCollection As INotifyCollectionChanged = TryCast(listBox.Items.SourceCollection, INotifyCollectionChanged) If notifyCollection IsNot Nothing Then If subscribe Then 'AutoScroll is turned on, subscribe to collection changed events. AddHandler notifyCollection.CollectionChanged, AddressOf listBox.AutoScroll_ItemsCollectionChanged Else 'AutoScroll is turned off, unsubscribe from collection changed events. RemoveHandler notifyCollection.CollectionChanged, AddressOf listBox.AutoScroll_ItemsCollectionChanged End If End If End Sub Private Sub AutoScroll_ItemsCollectionChanged(ByVal sender As Object, ByVal e As NotifyCollectionChangedEventArgs) If e.Action = NotifyCollectionChangedAction.Add Then Dim count As Integer = Items.Count ScrollIntoView(Items(count - 1)) End If End Sub Public Sub New() 'Subscribe to the AutoScroll property's items collection 'changed handler by default if AutoScroll is enabled by default. SubscribeToAutoScroll_ItemsCollectionChanged(Me, DirectCast(AutoScrollProperty.DefaultMetadata.DefaultValue, Boolean)) End Sub End Class
Code XAML : Sélectionner tout - Visualiser dans une fenêtre à part
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28 <Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:Test_Listbox_Autoscroll" xmlns:tools="clr-namespace:Test_Listbox_Autoscroll" mc:Ignorable="d" Title="MainWindow" Width="800" SizeToContent =" WidthAndHeight"> <Grid> <StackPanel > <tools:LoggingListBox x:Name="Listbox1" Margin=" 10" Background="Bisque" Height="180" ItemsSource="{Binding LST_ListBox1_Collection}" SelectedItem="{Binding LST_ListBox1_SelectedItem}"/> <CheckBox x:Name="ChkAutoScroll" Margin="10" Content="Auto Scroll" Checked="ChkAutoScroll_Checked" Click="ChkAutoScroll_Click"/> </StackPanel> </Grid> </Window>
MainWindow Code:
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25 Class MainWindow Public Sub New() ' Cet appel est requis par le concepteur. InitializeComponent() ' Ajoutez une initialisation quelconque après l'appel InitializeComponent(). Dim VM As New VueModele Me.DataContext = VM End Sub Private Sub ChkAutoScroll_Checked(sender As Object, e As RoutedEventArgs) End Sub Private Sub ChkAutoScroll_Click(sender As Object, e As RoutedEventArgs) If (ChkAutoScroll.IsChecked = True) Then Listbox1.AutoScroll = True Else Listbox1.AutoScroll = False End If End Sub End Class
ce qui m’intéresse c'est le VB.net. Mais je vous ai mis le C# car c'est le code d'origine, mais lui aussi l'autoscroll est toujours actif.
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