Get the ComboBox that a ComboBoxItem resides in - wpf

I need to find the ComboBox that a ComboBoxItem resides in.
In codebehind I catch an event when a ComboBoxItem is clicked, but I don't know which one of several ComboBoxes that the specific ComboBoxItem belongs to. How do I find the ComboBox?
Normally you can use LogicalTreeHelper.GetParent() and traverse up the logical tree from the ComboBoxItem to find the ComboBox. But this only works if the ComboBoxItems are added to the ComboBox manually, not when the items are applied to the ComboBox with databinding. When using databinding, the ComboBoxItems do not have the ComboBox as a logical parent (I don't understand why).
Any ideas?
More info:
Below is some code reconstructing my problem (not my actual code). If I would change from databinding the ComboBoxItems to setting them manually (in the XAML), the variable "comboBox" would be set to the correct ComboBox. Now comboBox is only null.
XAML:
<ComboBox Name="MyComboBox" ItemsSource="{Binding Path=ComboBoxItems, Mode=OneTime}" />
CodeBehind:
public MainWindow()
{
InitializeComponent();
MyComboBox.DataContext = this;
this.PreviewMouseDown += MainWindow_MouseDown;
}
public BindingList<string> ComboBoxItems
{
get
{
BindingList<string> items = new BindingList<string>();
items.Add("Item E");
items.Add("Item F");
items.Add("Item G");
items.Add("Item H");
return items;
}
}
private void MainWindow_MouseDown(object sender, MouseButtonEventArgs e)
{
DependencyObject clickedObject = e.OriginalSource as DependencyObject;
ComboBoxItem comboBoxItem = FindVisualParent<ComboBoxItem>(clickedObject);
if (comboBoxItem != null)
{
ComboBox comboBox = FindLogicalParent<ComboBox>(comboBoxItem);
}
}
//Tries to find visual parent of the specified type.
private static T FindVisualParent<T>(DependencyObject childElement) where T : DependencyObject
{
DependencyObject parent = VisualTreeHelper.GetParent(childElement);
T parentAsT = parent as T;
if (parent == null)
{
return null;
}
else if (parentAsT != null)
{
return parentAsT;
}
return FindVisualParent<T>(parent);
}
//Tries to find logical parent of the specified type.
private static T FindLogicalParent<T>(DependencyObject childElement) where T : DependencyObject
{
DependencyObject parent = LogicalTreeHelper.GetParent(childElement);
T parentAsT = parent as T;
if (parent == null)
{
return null;
}
else if(parentAsT != null)
{
return parentAsT;
}
return FindLogicalParent<T>(parent);
}

This is probably what you are looking for:
var comboBox = ItemsControl.ItemsControlFromItemContainer(comboBoxItem) as ComboBox;
I love how descriptive that method-name is.
On a side-note, there are some other useful methods which can be found in the property ItemsControl.ItemContainerGenerator which let you get the container associated with the templated data and vice versa.
On another side-note, you usually should not be using any of them and instead use data-binding actually.

Related

Wpf TabControl create only one view at all tabs

TabControl's ItemsSource property binded to collection in the ViewModel. ContentTemplate is ListView - UserControl. All the tabs use only one ListView control (the constructor of ListView is called only once). The problem is that all tabs have a common visual state - for example, if you change the size of any item in the one tab, this change will be on all tabs. How to create a separate ListView for each tab, but at the same time use ItemsSource property?
<TabControl Grid.Row="1" Grid.Column="2" TabStripPlacement="Bottom" >
<TabControl.ContentTemplate>
<DataTemplate DataType="viewModel:ListViewModel" >
<view:ListView />
</DataTemplate>
</TabControl.ContentTemplate>
<TabControl.ItemsSource>
<Binding Path="Lists"/>
</TabControl.ItemsSource>
</TabControl>
There's no easy way of doing this.
The problem is you have a WPF Template, which is meant to be the same regardless of what data you put behind it. So one copy of the template is created, and anytime WPF encounters a ListViewModel in your UI tree it draws it using that template. Properties of that control which are not bound to the DataContext will retain their state between changing DataSources.
You could use x:Shared="False" (example here), however this creates a new copy of your template anytime WPF requests it, which includes when you switch tabs.
When [x:Shared is] set to false, modifies Windows Presentation Foundation (WPF) resource retrieval behavior such that requests for a resource will create a new instance for each request, rather than sharing the same instance for all requests.
What you really need is for the TabControl.Items to each generate a new copy of your control for each item, but that doesn't happen when you use the ItemsSource property (this is by design).
One possible alternative which might work would be to create a custom DependencyProperty that binds to your collection of items, and generates the TabItem and UserControl objects for each item in the collection. This custom DP would also need to handle the collection change events to make sure the TabItems stay in sync with your collection.
Here's one I was playing around with. It was working for simple cases, such as binding to an ObservableCollection, and adding/removing items.
public class TabControlHelpers
{
// Custom DependencyProperty for a CachedItemsSource
public static readonly DependencyProperty CachedItemsSourceProperty =
DependencyProperty.RegisterAttached("CachedItemsSource", typeof(IList), typeof(TabControlHelpers), new PropertyMetadata(null, CachedItemsSource_Changed));
// Get
public static IList GetCachedItemsSource(DependencyObject obj)
{
if (obj == null)
return null;
return obj.GetValue(CachedItemsSourceProperty) as IList;
}
// Set
public static void SetCachedItemsSource(DependencyObject obj, IEnumerable value)
{
if (obj != null)
obj.SetValue(CachedItemsSourceProperty, value);
}
// Change Event
public static void CachedItemsSource_Changed(
DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
if (!(obj is TabControl))
return;
var changeAction = new NotifyCollectionChangedEventHandler(
(o, args) =>
{
var tabControl = obj as TabControl;
if (tabControl != null)
UpdateTabItems(tabControl);
});
// if the bound property is an ObservableCollection, attach change events
INotifyCollectionChanged newValue = e.NewValue as INotifyCollectionChanged;
INotifyCollectionChanged oldValue = e.OldValue as INotifyCollectionChanged;
if (oldValue != null)
newValue.CollectionChanged -= changeAction;
if (newValue != null)
newValue.CollectionChanged += changeAction;
UpdateTabItems(obj as TabControl);
}
static void UpdateTabItems(TabControl tc)
{
if (tc == null)
return;
IList itemsSource = GetCachedItemsSource(tc);
if (itemsSource == null || itemsSource.Count == null)
{
if (tc.Items.Count > 0)
tc.Items.Clear();
return;
}
// loop through items source and make sure datacontext is correct for each one
for(int i = 0; i < itemsSource.Count; i++)
{
if (tc.Items.Count <= i)
{
TabItem t = new TabItem();
t.DataContext = itemsSource[i];
t.Content = new UserControl1(); // Should be Dynamic...
tc.Items.Add(t);
continue;
}
TabItem current = tc.Items[i] as TabItem;
if (current == null)
continue;
if (current.DataContext == itemsSource[i])
continue;
current.DataContext = itemsSource[i];
}
// loop backwards and cleanup extra tabs
for (int i = tc.Items.Count; i > itemsSource.Count; i--)
{
tc.Items.RemoveAt(i - 1);
}
}
}
Its used from the XAML like this :
<TabControl local:TabControlHelpers.CachedItemsSource="{Binding Values}">
<TabControl.Resources>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding SomeString}" />
</Style>
</TabControl.Resources>
</TabControl>
A few things to note :
TabItem.Header is not set, so you'll have to setup a binding for it in TabControl.Resources
DependencyProperty implementation currently hardcodes the creation of the new UserControl. May want to do that some other way, such as trying to use a template property or perhaps a different DP to tell it what UserControl to create
Would probably need more testing... not sure if there's any issues with memory leaks due to change handler, etc
Based on #Rachel answer I made a few modifications.
First of all, you now have to specify a user control type as content template which is dynamically created.
I have also corrected a mistake in collectionChanged handler removal.
The code is the following:
public static class TabControlExtension
{
// Custom DependencyProperty for a CachedItemsSource
public static readonly DependencyProperty CachedItemsSourceProperty =
DependencyProperty.RegisterAttached("CachedItemsSource", typeof(IList), typeof(TabControlExtension), new PropertyMetadata(null, CachedItemsSource_Changed));
// Custom DependencyProperty for a ItemsContentTemplate
public static readonly DependencyProperty ItemsContentTemplateProperty =
DependencyProperty.RegisterAttached("ItemsContentTemplate", typeof(Type), typeof(TabControlExtension), new PropertyMetadata(null, CachedItemsSource_Changed));
// Get items
public static IList GetCachedItemsSource(DependencyObject dependencyObject)
{
if (dependencyObject == null)
return null;
return dependencyObject.GetValue(CachedItemsSourceProperty) as IList;
}
// Set items
public static void SetCachedItemsSource(DependencyObject dependencyObject, IEnumerable value)
{
if (dependencyObject != null)
dependencyObject.SetValue(CachedItemsSourceProperty, value);
}
// Get ItemsContentTemplate
public static Type GetItemsContentTemplate(DependencyObject dependencyObject)
{
if (dependencyObject == null)
return null;
return dependencyObject.GetValue(ItemsContentTemplateProperty) as Type;
}
// Set ItemsContentTemplate
public static void SetItemsContentTemplate(DependencyObject dependencyObject, IEnumerable value)
{
if (dependencyObject != null)
dependencyObject.SetValue(ItemsContentTemplateProperty, value);
}
// Change Event
public static void CachedItemsSource_Changed(
DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
{
if (!(dependencyObject is TabControl))
return;
var changeAction = new NotifyCollectionChangedEventHandler(
(o, args) =>
{
if (dependencyObject is TabControl tabControl && GetItemsContentTemplate(tabControl) != null && GetCachedItemsSource(tabControl) != null)
UpdateTabItems(tabControl);
});
// if the bound property is an ObservableCollection, attach change events
if (e.OldValue is INotifyCollectionChanged oldValue)
oldValue.CollectionChanged -= changeAction;
if (e.NewValue is INotifyCollectionChanged newValue)
newValue.CollectionChanged += changeAction;
if (GetItemsContentTemplate(dependencyObject) != null && GetCachedItemsSource(dependencyObject) != null)
UpdateTabItems(dependencyObject as TabControl);
}
private static void UpdateTabItems(TabControl tabControl)
{
if (tabControl == null)
return;
IList itemsSource = GetCachedItemsSource(tabControl);
if (itemsSource == null || itemsSource.Count == 0)
{
if (tabControl.Items.Count > 0)
tabControl.Items.Clear();
return;
}
// loop through items source and make sure datacontext is correct for each one
for (int i = 0; i < itemsSource.Count; i++)
{
if (tabControl.Items.Count <= i)
{
TabItem tabItem = new TabItem
{
DataContext = itemsSource[i],
Content = Activator.CreateInstance(GetItemsContentTemplate(tabControl))
};
tabControl.Items.Add(tabItem);
continue;
}
TabItem current = tabControl.Items[i] as TabItem;
if (!(tabControl.Items[i] is TabItem))
continue;
if (current.DataContext == itemsSource[i])
continue;
current.DataContext = itemsSource[i];
}
// loop backwards and cleanup extra tabs
for (int i = tabControl.Items.Count; i > itemsSource.Count; i--)
{
tabControl.Items.RemoveAt(i - 1);
}
}
}
This one is used the following way:
<TabControl main:TabControlExtension.CachedItemsSource="{Binding Channels}" main:TabControlExtension.ItemsContentTemplate="{x:Type YOURUSERCONTROLTYPE}">
<TabControl.Resources>
<Style BasedOn="{StaticResource {x:Type TabItem}}" TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding Name}" />
</Style>
</TabControl.Resources>
</TabControl>

What is the proper way to handle multiple datagrids in a tab control so that cells leave edit mode when the tabs are changed?

In wpf I setup a tab control that binds to a collection of objects each object has a data template with a data grid presenting the data. If I select a particular cell and put it into edit mode, leaving the grid by going to another tab this will cause the exception below to be thrown on returning the datagrid:
'DeferRefresh' is not allowed during an AddNew or EditItem transaction.
It appears that the cell never left edit mode. Is there an easy way to take the cell out of edit mode, or is something else going on here?
Update: It looks like if I do not bind the tab control to the data source, but instead explicitly define each tab and then bind each item in the data source to a content control this problem goes away. This is not really a great solution, so I would still like to know how to bind the collection directly to the tab control.
Update: So what I have actually done for my own solution is to use a ListView and a content control in place of a tab control. I use a style to make the list view look tab like. The view model exposes a set of child view models and allows the user to select one via the list view. The content control then presents the selected view model and each view model has an associated data template which contains the data grid. With this setup switching between view models while in edit mode on the grid will properly end edit mode and save the data.
Here is the xaml for setting this up:
<ListView ItemTemplate="{StaticResource MakeItemsLookLikeTabs}"
ItemsSource="{Binding ViewModels}"
SelectedItem="{Binding Selected}"
Style="{StaticResource MakeItLookLikeATabControl}"/>
<ContentControl Content="{Binding Selected}">
I'll accept Phil's answer as that should work also, but for me the solution above seems like it will be more portable between projects.
I implemented a behavior for the DataGrid based on code I found in this thread.
Usage:<DataGrid local:DataGridCommitEditBehavior.CommitOnLostFocus="True" />
Code:
using System.Collections.Generic;
using System.Reflection;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using System.Windows.Media;
/// <summary>
/// Provides an ugly hack to prevent a bug in the data grid.
/// https://connect.microsoft.com/VisualStudio/feedback/details/532494/wpf-datagrid-and-tabcontrol-deferrefresh-exception
/// </summary>
public class DataGridCommitEditBehavior
{
public static readonly DependencyProperty CommitOnLostFocusProperty =
DependencyProperty.RegisterAttached(
"CommitOnLostFocus",
typeof(bool),
typeof(DataGridCommitEditBehavior),
new UIPropertyMetadata(false, OnCommitOnLostFocusChanged));
/// <summary>
/// A hack to find the data grid in the event handler of the tab control.
/// </summary>
private static readonly Dictionary<TabPanel, DataGrid> ControlMap = new Dictionary<TabPanel, DataGrid>();
public static bool GetCommitOnLostFocus(DataGrid datagrid)
{
return (bool)datagrid.GetValue(CommitOnLostFocusProperty);
}
public static void SetCommitOnLostFocus(DataGrid datagrid, bool value)
{
datagrid.SetValue(CommitOnLostFocusProperty, value);
}
private static void CommitEdit(DataGrid dataGrid)
{
dataGrid.CommitEdit(DataGridEditingUnit.Cell, true);
dataGrid.CommitEdit(DataGridEditingUnit.Row, true);
}
private static DataGrid GetParentDatagrid(UIElement element)
{
UIElement childElement; // element from which to start the tree navigation, looking for a Datagrid parent
if (element is ComboBoxItem)
{
// Since ComboBoxItem.Parent is null, we must pass through ItemsPresenter in order to get the parent ComboBox
var parentItemsPresenter = VisualTreeFinder.FindParentControl<ItemsPresenter>(element as ComboBoxItem);
var combobox = parentItemsPresenter.TemplatedParent as ComboBox;
childElement = combobox;
}
else
{
childElement = element;
}
var parentDatagrid = VisualTreeFinder.FindParentControl<DataGrid>(childElement);
return parentDatagrid;
}
private static TabPanel GetTabPanel(TabControl tabControl)
{
return
(TabPanel)
tabControl.GetType().InvokeMember(
"ItemsHost",
BindingFlags.NonPublic | BindingFlags.GetProperty | BindingFlags.Instance,
null,
tabControl,
null);
}
private static void OnCommitOnLostFocusChanged(DependencyObject depObj, DependencyPropertyChangedEventArgs e)
{
var dataGrid = depObj as DataGrid;
if (dataGrid == null)
{
return;
}
if (e.NewValue is bool == false)
{
return;
}
var parentTabControl = VisualTreeFinder.FindParentControl<TabControl>(dataGrid);
var tabPanel = GetTabPanel(parentTabControl);
if (tabPanel != null)
{
ControlMap[tabPanel] = dataGrid;
}
if ((bool)e.NewValue)
{
// Attach event handlers
if (parentTabControl != null)
{
tabPanel.PreviewMouseLeftButtonDown += OnParentTabControlPreviewMouseLeftButtonDown;
}
dataGrid.LostKeyboardFocus += OnDataGridLostFocus;
dataGrid.DataContextChanged += OnDataGridDataContextChanged;
dataGrid.IsVisibleChanged += OnDataGridIsVisibleChanged;
}
else
{
// Detach event handlers
if (parentTabControl != null)
{
tabPanel.PreviewMouseLeftButtonDown -= OnParentTabControlPreviewMouseLeftButtonDown;
}
dataGrid.LostKeyboardFocus -= OnDataGridLostFocus;
dataGrid.DataContextChanged -= OnDataGridDataContextChanged;
dataGrid.IsVisibleChanged -= OnDataGridIsVisibleChanged;
}
}
private static void OnDataGridDataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var dataGrid = (DataGrid)sender;
CommitEdit(dataGrid);
}
private static void OnDataGridIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var senderDatagrid = (DataGrid)sender;
if ((bool)e.NewValue == false)
{
CommitEdit(senderDatagrid);
}
}
private static void OnDataGridLostFocus(object sender, KeyboardFocusChangedEventArgs e)
{
var dataGrid = (DataGrid)sender;
var focusedElement = Keyboard.FocusedElement as UIElement;
if (focusedElement == null)
{
return;
}
var focusedDatagrid = GetParentDatagrid(focusedElement);
// Let's see if the new focused element is inside a datagrid
if (focusedDatagrid == dataGrid)
{
// If the new focused element is inside the same datagrid, then we don't need to do anything;
// this happens, for instance, when we enter in edit-mode: the DataGrid element loses keyboard-focus,
// which passes to the selected DataGridCell child
return;
}
CommitEdit(dataGrid);
}
private static void OnParentTabControlPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var dataGrid = ControlMap[(TabPanel)sender];
CommitEdit(dataGrid);
}
}
public static class VisualTreeFinder
{
/// <summary>
/// Find a specific parent object type in the visual tree
/// </summary>
public static T FindParentControl<T>(DependencyObject outerDepObj) where T : DependencyObject
{
var dObj = VisualTreeHelper.GetParent(outerDepObj);
if (dObj == null)
{
return null;
}
if (dObj is T)
{
return dObj as T;
}
while ((dObj = VisualTreeHelper.GetParent(dObj)) != null)
{
if (dObj is T)
{
return dObj as T;
}
}
return null;
}
}
I have managed to work around this issue by detecting when the user clicks on a TabItem and then committing edits on visible DataGrid in the TabControl. I'm assuming the user will expect their changes to still be there when they click back.
Code snippet:
// PreviewMouseDown event handler on the TabControl
private void TabControl_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
if (IsUnderTabHeader(e.OriginalSource as DependencyObject))
CommitTables(yourTabControl);
}
private bool IsUnderTabHeader(DependencyObject control)
{
if (control is TabItem)
return true;
DependencyObject parent = VisualTreeHelper.GetParent(control);
if (parent == null)
return false;
return IsUnderTabHeader(parent);
}
private void CommitTables(DependencyObject control)
{
if (control is DataGrid)
{
DataGrid grid = control as DataGrid;
grid.CommitEdit(DataGridEditingUnit.Row, true);
return;
}
int childrenCount = VisualTreeHelper.GetChildrenCount(control);
for (int childIndex = 0; childIndex < childrenCount; childIndex++)
CommitTables(VisualTreeHelper.GetChild(control, childIndex));
}
This is in the code behind.
This bug is solved in the .NET Framework 4.5. You can download it at this link.
What I think you should do is pretty close to what #myermian said.
There is an event called CellEditEnding end this event would allow you to intercept and make the decision to drop the unwanted row.
private void dataGrid1_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
DataGrid grid = (DataGrid)sender;
TextBox cell = (TextBox)e.EditingElement;
if(String.IsNullOrEmpty(cell.Text) && e.EditAction == DataGridEditAction.Commit)
{
grid.CancelEdit(DataGridEditingUnit.Row);
e.Cancel = true;
}
}

How to deselect all selected items in a WPF treeview when clicking on some empty area?

I've got a rather funny problem with WPF. I have a tree-view, and selecting items works fine so far. The problem is, I want to unselect the currently selected item when the user clicks inside the blank area of the treeview. By default, the treeview keeps the current item selected, and I have added a context-menu option to deselect it, which is rather hardcore:
// Note: This is done recursivly from the start, so it
// works for child items as well
treeView.ItemContainerGenerator.ContainerFromItem(treeView.SelectedItem) as TreeViewItem).IsSelected = false;
Moreover, this is counter-intuitive, as it requires the user to right-click first, and second, after deselecting it with this way, the user cannot select it any more by clicking on the item. How is this supposed to work?
Edit: Some more information: I've added a handler to the TreeView to handle mouse click events, but the sender is always a TreeView instance, even if I click directly on a TreeViewItem. If I add a handler to my TreeView.ItemTemplate instead (i.e. the first child in the template), I never get events when I click on the empty area (which is rather logical). The code looks like this:
private void MyTreeView_MouseUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if ((sender as TreeViewItem) == null)
{
// Always triggered
System.Diagnostics.Trace.Write("Empty area clicked");
}
}
And the XAML for this is:
<TreeView x:Name="MyTreeView" Margin="3" MouseUp="MyTreeView_MouseUp">
I found this to work much better for me. I check the originalsource which for me if it comes form a treeviewitem will be an image or a textblock. I also use a view object with a HierarchicalDataTemplate and the BasicTreeViewBase is the base class for all of my different objects. Here is the code.
private void TemplateTreeView_MouseDown(object sender, MouseButtonEventArgs e)
{
if (e.ChangedButton == MouseButton.Right && !(e.OriginalSource is Image) && !(e.OriginalSource is TextBlock))
{
BasicTreeViewBase item = TemplateTreeView.SelectedItem as BasicTreeViewBase;
if (item != null)
{
TemplateTreeView.Focus();
item.IsSelected = false;
}
}
}
The un-selectable problem can be solved with a call to Focus on the TreeView after setting TreeViewItem.IsSelected.
There can be two more problem :
The treeview is binded so the SelectedItem is an item of the binded collection.
There is many levels so ItemContainerGenerator do not contain deepest level objects
for all this reason i use this function, but the selection must not fire any events.
private void UnselectTreeViewItem(TreeView pTreeView)
{
if(pTreeView.SelectedItem == null)
return;
if(pTreeView.SelectedItem is TreeViewItem)
{
(pTreeView.SelectedItem as TreeViewItem).IsSelected = false;
}
else
{
TreeViewItem item = pTreeView.ItemContainerGenerator.ContainerFromIndex(0) as TreeViewItem;
if (item != null)
{
item.IsSelected = true;
item.IsSelected = false;
}
}
}
I implemented a general selection control once, and required this behaviour.
This is how my method looked (adapted for treeview):
protected override void OnMouseUp(MouseButtonEventArgs e)
{
base.OnMouseUp(e);
DependencyObject dpSource = e.OriginalSource as DependencyObject;
if (dpSource.FindVisualAncestor(o => typeof(TreeViewItem).IsAssignableFrom(o.GetType())) == null)
UnselectAll();
}
Basically, walk up the tree from the source. If a TreeViewItem was not found, than the user clicked empty space.
Use the extension class below
public static class TreeViewExtensions
{
public static TreeViewItem ContainerFromItem(this TreeView treeView, object item)
{
TreeViewItem containerThatMightContainItem = (TreeViewItem)treeView.ItemContainerGenerator.ContainerFromItem(item);
if (containerThatMightContainItem != null)
return containerThatMightContainItem;
else
return ContainerFromItem(treeView.ItemContainerGenerator, treeView.Items, item);
}
private static TreeViewItem ContainerFromItem(ItemContainerGenerator parentItemContainerGenerator, ItemCollection itemCollection, object item)
{
foreach (object curChildItem in itemCollection)
{
TreeViewItem parentContainer = (TreeViewItem)parentItemContainerGenerator.ContainerFromItem(curChildItem);
TreeViewItem containerThatMightContainItem = (TreeViewItem)parentContainer.ItemContainerGenerator.ContainerFromItem(item);
if (containerThatMightContainItem != null)
return containerThatMightContainItem;
TreeViewItem recursionResult = ContainerFromItem(parentContainer.ItemContainerGenerator, parentContainer.Items, item);
if (recursionResult != null)
return recursionResult;
}
return null;
}
}
Then in MouseDown event of treeview use the extension method as below:
private void trview_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if ((sender as TreeViewItem) == null)
{
if (this.trview.ContainerFromItem(trview.SelectedItem) != null)
{
this.trview.ContainerFromItem(trview.SelectedItem).IsSelected = false;
}
}
this.trview.Focus();
}
Hope it works for you. I have it working in this way...
I was running into this situation myself with a custom Tree List View implementation after looking for a long time I finally found a solution that worked for me.
The full explanation can be found at http://social.msdn.microsoft.com/Forums/vstudio/en-US/36aca7f7-0b47-488b-8e16-840b86addfa3/getting-treeviewitem-for-the-selected-item-in-a-treeview
The basic idea is you capture the TreeViewItem.Selected event and save the source of the event into the Tag attribute on your TreeView. Then when you need to clear it, you can access the Tag attribute on your control and set the IsSelected value to False. This works for me with 2 levels of nested children. Hopefully it will work for you.
For persistence sake:
TreeView declaration
<TreeView Name="myTreeView" TreeViewItem.Selected="OnItemSelected"
ItemsSource="{Binding Source={StaticResource myHierarchicalData}}"/>
Event Handler
private void OnItemSelected(object sender, RoutedEventArgs e)
{
myTreeView.Tag = e.OriginalSource;
}
Clear selection logic
if (myTreeView.SelectedItem != null)
{
TreeViewItem selectedTVI = myTreeView.Tag as TreeViewItem;
// add your code here mine was selectedTVI.IsSelected = false;
}
This will deselect the currently selected TreeViewItem if none were clicked:
private void MyTreeView_PreviewMouseDown(object sender, MouseButtonEventArgs e) {
if ((sender as TreeViewItem) == null) {
TreeViewItem item = MyTreeView.SelectedItem as TreeViewItem;
if(item != null){
item.IsSelected = false;
}
}
}
Hope this is what you were looking for!
MVVM: Call this method in the eventhandler righ/left mouse click:
private void SetTreeViewSelection(object sender, MouseButtonEventArgs mouseButtonEventArgs)
{
var treeView = (TreeView)sender;
if (treeView.SelectedItem == null)
{
return;
}
IInputElement dropNode = treeView.InputHitTest(mouseButtonEventArgs.GetPosition(treeView));
if (dropNode is ScrollViewer)
{
var myBindableObject = (MyBindableObject)treeView.SelectedItem;
myBindableObject.IsSelected = false;
}
}
For a C# treeview you use treeview.SelectedNode = null; I'm not sure if this works for WPF.

WPF - Animate ListBox.ScrollViewer.HorizontalOffset?

I have a collection of Visuals in a ListBox. I need to find the XPosition of an element inside it and then animate the HorizontalOffset of the ListBox's ScrollViewer. Essentially I want to created an animated ScrollIntoView method.
This gives me a couple of problems. Firstly, how can I get a reference to the ListBoxs scrollviewer? Secondly, how can i get the relative XPosition or HozintalOfffset of an arbitrary element in the ListBox?
I'm not reponding to any input on the ListBox itself so I can't use Mouse related properties.
I don't think you will be able to use a WPF storyboard for the animation because storyboards animate WPF dependency properties. You will need to call ScrollViewer.ScrollToHorizontalOffset(double) to scroll.
You could try creating a custom dependency property that calls SetHorizontalOffset in the OnDependencyPropertyChanged() function. Then you could animate this property.
public static readonly DependencyProperty ScrollOffsetProperty =
DependencyProperty.Register("ScrollOffset", typeof(double), typeof(YOUR_TYPE),
new FrameworkPropertyMetadata(0.0, new PropertyChangedCallback(OnScrollOffsetChanged)));
public double ScrollOffset
{
get { return (double)GetValue(ScrollOffsetProperty); }
set { SetValue(ScrollOffsetProperty, value); }
}
private static void OnScrollOffsetChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
{
YOUR_TYPE myObj = obj as YOUR_TYPE;
if (myObj != null)
myObj.SCROLL_VIEWER.ScrollToHorizontalOffset(myObj.ScrollOffset);
}
To get the scroll viewer you can use the VisualTreeHelper to search the visual children of the ListBox. Save a reference to the ScrollViewer because you will need it later. Try this:
public static childItem FindVisualChild<childItem>(DependencyObject obj)
where childItem : DependencyObject
{
// Iterate through all immediate children
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
if (child != null && child is childItem)
return (childItem)child;
else
{
childItem childOfChild = FindVisualChild<childItem>(child);
if (childOfChild != null)
return childOfChild;
}
}
return null;
}
This function returns the first visual child of the parameter type. Call FindVisualChild<ScrollViewer>(ListBox) to get the ScrollViewer.
Finally, try using UIElement.TranslatePoint(Point, UIElement) to get the X position of the item. Call this function on the item, pass in 0,0 for the point, and pass in the ScrollViewer.
Hope this helps.
I'm not sure if my method is good practice but for the limited time I had it seemed to work okay. Instead of using a story board I just used a DispatcherTimer instead.
ScrollLeftButtonCommand = new DelegateCommand(
o =>
{
var scrollViewer = (ScrollViewer)o;
scrollTimer = new DispatcherTimer();
scrollTimer.Start();
scrollTimer.Interval = TimeSpan.FromMilliseconds(30);
scrollTimer.Tick += (s, e) =>
{
scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset - 50);
if (scrollViewer.HorizontalOffset <= 0)
{
scrollTimer.Stop();
}
};
});
Make sure it's a DispatchTimer so the thread is able to take control of the UI element
Also remember to bind to your object in your view!
<Button CommandParameter="{Binding ElementName=MyScrollViewer }"
Command="{Binding ScrollLeftButtonCommand }"/>

Silverlight Toolkit Treeview: Getting the parent of a selected item

I'm using the TreeView component from the Silverlight toolkit and I'm trying to get the parent of a selected node. The TreeView is bound to a series of objects, so directly working with a TreeViewItem appears to be out of the question.
<toolkit:TreeView SelectedItemChanged="DoStuff" DisplayMemberPath="Name" ItemsSource="{Binding MyCollection}">
<toolkit:TreeView.ItemTemplate>
<common:HierarchicalDataTemplate ItemsSource="{Binding MySubCollection}">
<StackPanel>
<TextBlock Text="{Binding Name}" />
</StackPanel>
</common:HierarchicalDataTemplate>
</toolkit:TreeView.ItemTemplate>
</toolkit:TreeView>
Is there a way to fetch the parent of an item selected in the DoStuff event?
As long as you've downloaded the latest Silverlight Toolkit then this is easy using the TreeViewExtensions that are included.
Download the Silverlight Toolkit and install.
Add a reference to System.Windows.Controls.Toolkit (from the Silverlight Toolkit)
Use the GetParentItem() extension method, like so:
private void DoStuff(object sender, RoutedPropertyChangedEventArgs<object> e)
{
if (e.NewValue != null)
{
var parent = ((TreeView)sender).GetParentItem(e.NewValue);
//
// Do stuff with parent, this snippet updates
// a TextBlock showing the name of the current parent
if (parent != null)
{
Status.Text = parent.ToString();
}
}
}
Why don't you just have the objects in MySubcollection keep a reference to their parent?
Suppose your Tree's name is "tree", this should do the trick
((tree.SelectedItem as TreeViewItem).Parent as SomeObjectOfYours)
Justin Angel wrote about "advanced" TreeView uses, among them finding arbirtraty elements in a treeview by their bound object.
Since I am comparatively new to Silverlight, I am not sure if there is a better, more elegant way, but you could use one of his methods to find the parent.
I imagine using a call this way:
TreeViewItem trvi = ContainerFromItem(tree, tree.SelectedItem);
MySubCollectionItem parentItem = ItemFromContainer(tree, trvi.Parent); // note the "Parent" here
With the extension methods below available from somewhere:
public static TreeViewItem ContainerFromItem(this TreeView treeView, object item)
{
TreeViewItem containerThatMightContainItem = (TreeViewItem)treeView.ItemContainerGenerator.ContainerFromItem(item);
if (containerThatMightContainItem != null)
return containerThatMightContainItem;
else
return ContainerFromItem(treeView.ItemContainerGenerator, treeView.Items, item);
}
private static TreeViewItem ContainerFromItem(ItemContainerGenerator parentItemContainerGenerator, ItemCollection itemCollection, object item)
{
foreach (object curChildItem in itemCollection)
{
TreeViewItem parentContainer = (TreeViewItem)parentItemContainerGenerator.ContainerFromItem(curChildItem);
if (parentContainer == null)
return null;
TreeViewItem containerThatMightContainItem = (TreeViewItem)parentContainer.ItemContainerGenerator.ContainerFromItem(item);
if (containerThatMightContainItem != null)
return containerThatMightContainItem;
TreeViewItem recursionResult = ContainerFromItem(parentContainer.ItemContainerGenerator, parentContainer.Items, item);
if (recursionResult != null)
return recursionResult;
}
return null;
}
public static object ItemFromContainer(this TreeView treeView, TreeViewItem container)
{
TreeViewItem itemThatMightBelongToContainer = (TreeViewItem)treeView.ItemContainerGenerator.ItemFromContainer(container);
if (itemThatMightBelongToContainer != null)
return itemThatMightBelongToContainer;
else
return ItemFromContainer(treeView.ItemContainerGenerator, treeView.Items, container);
}
private static object ItemFromContainer(ItemContainerGenerator parentItemContainerGenerator, ItemCollection itemCollection, TreeViewItem container)
{
foreach (object curChildItem in itemCollection)
{
TreeViewItem parentContainer = (TreeViewItem)parentItemContainerGenerator.ContainerFromItem(curChildItem);
if (parentContainer == null)
return null;
TreeViewItem itemThatMightBelongToContainer = (TreeViewItem)parentContainer.ItemContainerGenerator.ItemFromContainer(container);
if (itemThatMightBelongToContainer != null)
return itemThatMightBelongToContainer;
TreeViewItem recursionResult = ItemFromContainer(parentContainer.ItemContainerGenerator, parentContainer.Items, container) as TreeViewItem;
if (recursionResult != null)
return recursionResult;
}
return null;
}

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