How to call Grid from within CS file in WPF - wpf

Question

Unable to call a grid inside a listbox anymore... my xaml is as follows.
<UserControl x:Class="WPFPurpleButtonTest.InstrumentUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WPFPurpleButtonTest"
mc:Ignorable="d"
d:DesignHeight="750" d:DesignWidth="900">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TabControl x:Name="tabControl" HorizontalAlignment="Left" Height="706" Margin="24,34,0,-212" VerticalAlignment="Top" Width="850" Grid.RowSpan="2">
<TabItem Header="TabItem" Name="mainTab">
<Grid Background="#FFE5E5E5" Margin="0,0,-396,-255">
<Label x:Name="colourName" Content="PURPLE" HorizontalAlignment="Left" Height="93" Margin="284,88,0,0" VerticalAlignment="Top" Width="243" FontWeight="Bold" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" FontSize="50" Foreground="#FFDC00FF"/>
<Button x:Name="testButton" Content="Button" HorizontalAlignment="Left" Margin="365,181,0,0" VerticalAlignment="Top" Width="75" Click="TestButton_Click"/>
<Label x:Name="label" Content="Row Size" HorizontalAlignment="Left" Margin="198,211,0,0" VerticalAlignment="Top" Foreground="#FFDC00FF"/>
<Label x:Name="label_Copy" Content="Column Size" HorizontalAlignment="Left" Margin="432,211,0,0" VerticalAlignment="Top" Foreground="#FFDC00FF"/>
<Button x:Name="createGrid" Content="Create Grid" HorizontalAlignment="Left" Margin="365,273,0,0" VerticalAlignment="Top" Width="75" Click="CreateGrid_Click"/>
<TextBox x:Name="rowSizeText" HorizontalAlignment="Left" Height="23" Margin="278,214,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="62"/>
<TextBox x:Name="columnSizeText" HorizontalAlignment="Left" Height="23" Margin="522,215,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="62"/>
</Grid>
</TabItem>
<TabItem Header="TabItem" Name="gridTab">
<ListBox x:Name="listbox1" ScrollViewer.VerticalScrollBarVisibility="Disabled">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel IsItemsHost="True" Orientation="Vertical" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Margin="20" HorizontalAlignment="Center">
<Viewbox>
<Grid x:Name="wellGrid" Grid.Row="1" ShowGridLines="True"
local:GridHelpers.RowCount="{Binding RowCount}"
local:GridHelpers.ColumnCount="{Binding ColumnCount}" Margin="15,15,15,15" />
</Viewbox>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</TabItem>
</TabControl>
</Grid>
</UserControl>
I want to be able to call wellGrid.Children like I used to when the grid was not in a listbox but not entirely sure how to do that now the grid is in the listbox.

Answer 1

The Grid is part of theDataTemplatethat is assigned to theListBoxItem. You need to get theContentPresenterof the item. This is where theDataTemplate` is applied.
private void Button_Click(object sender, RoutedEventArgs e)
{
int selectedItemIndex = this.listbox1.SelectedIndex;
if (selectedItemIndex == -1)
{
return;
}
var itemContainer = this.listbox1.ItemContainerGenerator.ContainerFromIndex(selectedItemIndex) as ListBoxItem;
if (TryFindChildElement(itemContainer, out ContentPresenter contentPresenter))
{
// Get the Grid
var grid = contentPresenter.ContentTemplate.FindName("wellGrid", myContentPresenter) as Grid;
}
}
// Helper to traverse the visual tree
private bool TryFindChildElement<TElement>(DependencyObject parent, out TElement resultElement) where TElement : DependencyObject
{
resultElement = null;
for (var childIndex = 0; childIndex < VisualTreeHelper.GetChildrenCount(parent); childIndex++)
{
DependencyObject childElement = VisualTreeHelper.GetChild(parent, childIndex);
if (childElement is Popup popup)
{
childElement = popup.Child;
}
if (childElement is TElement)
{
resultElement = childElement as TElement;
return true;
}
if (TryFindChildElement(childElement, out resultElement))
{
return true;
}
}
return false;
}