Access treeviewitem from HierarchicalDataTemplate in WPF - wpf

Question

I am trying to access the treeviewitem created using HierarchicalDataTemplate based on the Name of the header. Also i want to access the control inside (in this case rectangle) the treeviewitem and change its color. I tried many ways but no success. Below is my code. I am generating Treeview using custom class and xml.
public partial class Window1 : Window
{
ObservableCollection<Step> TreeViewTemplate;
public Window1()
{
TreeViewTemplate = new ObservableCollection<Step>();
InitializeComponent();
SetDataTemplate("NEWSITECOPPER_PROPOSAL", "Proposal");
tvMain.ItemsSource = TreeViewTemplate;
getTreeViewItem();
}
private void getTreeViewItem()
{
TreeViewItem item = (TreeViewItem)(tvMain.ItemContainerGenerator.ContainerFromItem(tvMain.Items[3]));
}
private void SetDataTemplate(string ProcessName, string journeyName)
{
try
{
TreeViewTemplate.Clear();
//XDocument xDoc = XDocument.Load(#"C:\Users\606347769\Desktop\Hemil\Others\TreeView\TreeView\Data.xml");
XDocument xDoc = XDocument.Load(#"C:\Users\606347769\Documents\Visual Studio 2008\Projects\TestAPplication\WpfApplication1\ProcessJourneyCriteria.xml");
var JourneySteps = xDoc.Elements("ProcessAreas").Elements("Process").Where(x =>
x.Attribute("name").Value == ProcessName).Select(y =>
y.Elements("Journey").Where(k => k.Attribute("name").Value == journeyName));
var FinalSteps = JourneySteps.FirstOrDefault();
FinalSteps.Elements("Step").ToList<XElement>().ForEach(x =>
{
string key = x.Attribute("name").Value;
ObservableCollection<ChildStep> value = new ObservableCollection<ChildStep>();
x.Elements("ChildStep").ToList<XElement>().ForEach(y =>
{
ObservableCollection<GrandChildStep> GC = new ObservableCollection<GrandChildStep>();
y.Elements("GrandChildStep").ToList<XElement>().ForEach(k =>
{
GC.Add(new GrandChildStep { Name = k.Attribute("name").Value });
});
value.Add(new ChildStep { Name = y.Attribute("name").Value, GrandChildStep = GC });
});
TreeViewTemplate.Add(new Step { Name = key, ChildStep = value });
});
}
catch (Exception)
{
}
}
}
Below is the custom class i have created
class Step
{
public string Name { get; set; }
public System.Collections.ObjectModel.ObservableCollection<ChildStep> ChildStep { get; set; }
}
class ChildStep
{
public string Name { get; set; }
public System.Collections.ObjectModel.ObservableCollection<GrandChildStep> GrandChildStep { get; set; }
}
class GrandChildStep
{
public string Name { get; set; }
}

Answer 1

You should expose everything you want to access on your (view) model and just bind to it, like the Background of the shape or the IsSelected property of the item (needs to be bound in ItemContainerStyle).
If you need to "access UI controls" in WPF you are usually doing something wrong.

Answer 2

name the child,for eg. in your case x:Name="Rect" to Rectangle
then
Declare this helper method in your Code
T GetVisualChild<t>(DependencyObject parent, string name) where T : Visual
{
T child = default(T);
int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < numVisuals; i++)
{
Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
child = v as T;
if (child == null)
{
child = GetVisualChild<t>(v, name);
}
if (child != null)
{
break;
}
}
return child;
}
then
just declare Rectangle Rect=new Rectangle(); in constructor or loaded event.
and when you want to access the child. use that declared helper method. for eg.
Rect=GetVisualChild<treeview>(this, "Rect")
Note: here "treeview" is the name of parent You may give the name of parent accessing the child directly.