Changing the Background color of some ListBox Items

Question

The ListBox is defined as follows:

 <ListBox x:Name="EditableStructs" Grid.Row="5" Grid.Column="1" Margin="930,62,0,40"  SelectionMode="Single"  Grid.ColumnSpan="2" Background="PowderBlue" Height="500"
                           ScrollViewer.VerticalScrollBarVisibility="Visible" ScrollViewer.CanContentScroll="True"  ItemsSource="{Binding AutoNames,Mode=TwoWay}" HorizontalAlignment="Left" Width="220"  >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="Auto"/>
                            <ColumnDefinition Width="Auto"/>
                            <ColumnDefinition Width="*"/>
                        </Grid.ColumnDefinitions>
                        <TextBlock Name="TextInd" Text="{Binding NamInd, Mode=OneWay}"  Grid.Column="0" Padding="1,5" HorizontalAlignment="Stretch"/>
                        <CheckBox IsChecked="{Binding IsAccepted, Mode=TwoWay}" Grid.Column="1"  Padding="5,5" VerticalAlignment="Center" HorizontalAlignment="Center"  />
                        <TextBox Text="{Binding  StrName, Mode=TwoWay}"  Background="{Binding MyBackground}"  Grid.Column="2" HorizontalAlignment="Stretch"/>
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

The number of items as well as which items should have a different colour is known at runtime when the strings to be displayed are being generated.

foreach (string str in EditedList)
            {
                AutoNames.Add(new EditableStructures { StrName = str,  IsAccepted = false, NamInd = j});
                j++;
            }

EditableStructs.ItemsSource = (System.Collections.IEnumerable)AutoNames;

Clearly indexing the ListBox makes sense after the ListBox has been generated.
My problem is to select programmatically the ListBox items whose colour is to be changed:
I tried the following:

for(int i =0; i < EditableStructs.Items.Count; i++)
            {
                if (IsGuessed[i])
                    EditableStructs.TextBox[i].Background = "Red";
            }

But it does not work even if I replace TextBox with Items

I would appreciate any kind of help. Thank you in advance

Answer 1

You could try to refer the following code to your project.
MainWindow.xaml:

 <StackPanel>  
        <ListBox x:Name="EditableStructs"   SelectionMode="Single" Width="400"  Background="PowderBlue" Height="300"  
                             ScrollViewer.VerticalScrollBarVisibility="Visible" ScrollViewer.CanContentScroll="True"   
                  ItemsSource="{Binding AutoNames,Mode=TwoWay}"  >  
  
            <ListBox.ItemTemplate>  
                <DataTemplate>  
                    <Grid x:Name="grid">  
                        <Grid.ColumnDefinitions>  
                            <ColumnDefinition Width="Auto"/>  
                            <ColumnDefinition Width="Auto"/>  
                            <ColumnDefinition Width="*"/>  
                        </Grid.ColumnDefinitions>  
                        <TextBlock Name="TextInd" Text="{Binding NamInd, Mode=OneWay}"  Grid.Column="0" Padding="1,5" HorizontalAlignment="Stretch"/>  
                        <CheckBox IsChecked="{Binding IsAccepted, Mode=TwoWay}" Grid.Column="1"  Padding="5,5" VerticalAlignment="Center" HorizontalAlignment="Center"  />  
                        <TextBox x:Name="tb" Text="{Binding  StrName, Mode=TwoWay}"  Background="{Binding MyBackground}"  Grid.Column="2" HorizontalAlignment="Stretch"/>  
                    </Grid>  
                </DataTemplate>  
            </ListBox.ItemTemplate>  
        </ListBox>  
        <Button x:Name="btn" Content="change" Click="btn_Click"/>  
    </StackPanel>  

MainWindow.xaml.cs:

using System.Collections.Generic;  
using System.Collections.ObjectModel;  
using System.ComponentModel;  
using System.Windows;  
using System.Windows.Controls;  
using System.Windows.Media;  
  
namespace ListBoxBackgroundDynamicallySet  
{  
  public partial class MainWindow : Window  
  {  
    public ObservableCollection<EditableStructures> AutoNames { get; set; }  
    public List<string> EditedList = new List<string>() { "name1", "name2", "name3", "name4", "name5", "name6" };  
    int j = 0;  
    public MainWindow()  
    {  
      InitializeComponent();  
      AutoNames = new ObservableCollection<EditableStructures>();  
      DataContext = this;  
      foreach (string str in EditedList)  
      {  
        if (j % 3 == 0)  
        {  
          AutoNames.Add(new EditableStructures { StrName = str, IsAccepted = false, NamInd = j, SpecialFeatures = SpecialFeatures.Highlight , IsGuessed=false });  
        }  
        else if (j % 3 == 1)  
        {  
          AutoNames.Add(new EditableStructures { StrName = str, IsAccepted = true, NamInd = j, SpecialFeatures = SpecialFeatures.Color,IsGuessed = true });  
        }  
        else  
        {  
          AutoNames.Add(new EditableStructures { StrName = str, IsAccepted = false, NamInd = j, SpecialFeatures = SpecialFeatures.None, IsGuessed = false });  
        }  
        j++;  
      }  
  
      EditableStructs.ItemsSource = (System.Collections.IEnumerable)AutoNames;  
    }  
    List<bool> IsGuessed = new List<bool>() { true, false, true, true, false, false };  
     private void btn_Click(object sender, RoutedEventArgs e)  
{  
  for (int i = 0; i < EditableStructs.Items.Count; i++)  
  {  

    if (IsGuessed[i])  
    {  
      TextBox gg = FindDescendant<TextBox>(EditableStructs.ItemContainerGenerator.ContainerFromIndex(i) as ListBoxItem);  
      gg.Background= Brushes.Red;   
    }  
    else  
    {  
      TextBox gg = FindDescendant<TextBox>(EditableStructs.ItemContainerGenerator.ContainerFromIndex(i) as ListBoxItem);  
      gg.Background = Brushes.White;  
    }  
  }  
}  
    public T FindDescendant<T>(DependencyObject obj) where T : DependencyObject  
    {  
      if (obj is T)  
        return obj as T;  
  
      int childrenCount = VisualTreeHelper.GetChildrenCount(obj);  
      if (childrenCount < 1)  
        return null;  
  
      for (int i = 0; i < childrenCount; i++)  
      {  
        DependencyObject child = VisualTreeHelper.GetChild(obj, i);  
        if (child is T)  
          return child as T;  
      }  
      for (int i = 0; i < childrenCount; i++)  
      {  
        DependencyObject child = FindDescendant<T>(VisualTreeHelper.GetChild(obj, i));  
        if (child != null && child is T)  
          return child as T;  
      }  
      return null;  
    }  
  }  
  
  public enum SpecialFeatures  
  {  
    None,  
    Color,  
    Highlight  
  }  
  public class EditableStructures : INotifyPropertyChanged  
  {  
    public string StrName { get; set; }  
    public bool IsAccepted { get; set; }  
    public int NamInd { get; set; }  
    public bool IsGuessed { get;set;}  
    private SpecialFeatures _specialFeatures;  
    public SpecialFeatures SpecialFeatures  
    {  
      get { return _specialFeatures; }  
      set  
      {  
        _specialFeatures = value;  
        OnPropertyChanged("SpecialFeatures");  
      }  
    }  
    public event PropertyChangedEventHandler PropertyChanged;  
  
    protected void OnPropertyChanged(string name)  
    {  
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));  
    }  
  }  
}  

The result:

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Answer 2

Hi @Hui Liu-MSFT ,
I have answered my concerns about your proposed solution.
Thank you