How do I expand the node by clicking on the item text?
Purpose is to make it easier to expand or close a node, apart from depending on the Expander arrow button.
This seems to work. This toggles the item expanded/collapsed, but you could do item.IsExpanded = true; instead if you like.
TreeViewItem item = (TreeViewItem)treeView.ItemContainerGenerator.ContainerFromItem(treeView.SelectedItem);
item.IsExpanded = !item.IsExpanded;
You can fire this code in the mouse-button-up event handler of your label. If you put it in the mouse-down event handler, the tree view item won't have been selected yet.
Related
I have listbox bound to a collection of PhoneEntity. I also have a Remove button and it's command's CanExecute returns true if the listbox's SelectedItem != null. Pretty standard.
When I select a list item, the Remove button is enabled. But when I attempt to click the button, as soon as the button receives the focus on mouse down, the listbox's SelectedItem becomes null, so the button disables and cannot be clicked.
How do I keep the lisbox's selected item even if the list loses focus?
Thanks
It isn't pretty but... make a global variable to hold the selection index. Handle the on selection change and assign the selected index. Then handle the onFocusLost event and set the selection to that global variable.
I have a ListView control which is bound to a ObservableCollection, I want to add a specific button at the end of the last item, so that when user click the button, clear up the colltions, then hide the button. Also, if the collection is empty, don't like the button display. After searching, I found many solutions on how to change the last item's style, but in my scenario, the button isn't the element of the ItemsSource. Anyone can help?
Thanks
Add the button to the template so it appears on every element in the ListView. Then use a trigger to show/hide the button based on whether the item is the last item in the list.
One way to do this is to expose the last item in your list via a property on your ViewModel. The trigger should compare the DataContext of the template, which is the current item, against the LastItem. Success should set the visibility of the button.
I hope this helps.
In WPF ItemsControl, dragging an item (not selected) with an already selected item with control key pressed, does not give the clicked item into selected items list of the items control. Therefor the second item (which wasn't selected but dragged) never gets dropped as it is not in the selected list of items control.
The DragInfo object is being created on drag source's mouse left button down event.
Instead of using the selected item, use InputHitTest in the MouseDown event to find the element that was clicked, and use this element's DataContext to create the DragInfo object.
I'm not sure if this is what you want, but you can handle OnPreviewMouseleftButtonDown event and add the dragged (but not selected) item to SelectedItems.
In WPF I have a TreeView control where a particular item can be selected either by the user selecting the item directly in the tree view or by clicking on a screen control. The tree view is displaying a list of elements that are being displayed on a user defined form, basically a form designer application.
Here is my problem. When the user clicks on a screen control it calls a method that returns the TreeViewItem that represents the element. It then sets the IsSelected property to true for this element. It correctly changes the visual indicator in the TreeView and it raised the SelectedItemChanged event in the TreeView. This is all good.
However, it appears that somewhere behind the scenes the TreeView still thinks the previous item is selected. Here is why I have come to this conclusion. If I select ElementA by clicking on it in the TreeView is it correctly selected. If I then select ElementB by clicking on the screen control and programmatically setting the IsSelected property for the ElementB TreeViewItem it appears to have selected it correctly. Now if I select ElementA again by clicking on it in the TreeView it does nothing. The SelectedItemChanged event is not raised and the reverse selection box that indicates the selected item stays on ElementB. If I click on ElementB in the TreeView it also does not raise the SelectedItemChanged event, however it does not appear to update the internal flag since if I then click on ElementA on the TreeView it processes it correctly and raises the event.
The only workaround that I have found for this is in the SelectedItemChanged event handler to call the Focus method for the now selected TreeViewItem. If I do this I get the expected behaviour when I select screen controls and programmatically change the selected TreeViewItem.
This is not an acceptable solution though as it creates focus change flicker. When I select items on my form window the focus goes to the TreeView control and then back to the form, causing flicker and slight delay.
Anyone have any indeas.
Update
As requested here is some code. Here is my method of my Explorer window which is the manager of the TreeView in question.
public bool SelectItemByName(String controlName)
{
bool fReturn = false;
TreeViewItem tviToSelect = FindItemByName(_tviMaster, controlName);
if (tviToSelect != null && _tviSelectedItem != tviToSelect)
{
tviToSelect.IsSelected = true;
// Make sure the selected item is visible in the TreeView by expanding all of the parent nodes
ExpandAllParents(tviToSelect);
tviToSelect.BringIntoView();
fReturn = true;
}
return fReturn;
}
Every element has a unique identifier that I use as a cross reference between different areas of the interface. When you click a screen control it uses its identifier to find the cooresponding TreeViewItem in the TreeView. Then this code sets it as selected.
Then in my SelectedItemChanged event handler I had to include the following line.
_tviSelectedItem.Focus();
This fixes my initial issue but introducing the unwant screen flicker.
To recap, I select ElementA in the TreeView directly, then select one or more other elements in the form designer which in turn calls SelectItemByName to programatically set the selected item. All visual indicators show that this worked. In the TreeView the highlighted item changes to the new item that is selected. After selecting any number of elements through the form designer interface if you select ElementA by clicking on it directly in the TreeView it does nothing. It does not get highlighted and it does not fire the SelectedItemChanged event. If you inspect the SelectedItem and SelectedValue properties of the TreeView they all correctly coorespond to the item that was programmatically selected. However, the control somewhere appears to think that ElementA is still selected and doesn't recognize that the selection is changing.
I cannot believe that other people haven't run into this. It appears to be a significant flaw in the TreeView contol in WPF. Not sure if WinForms has the same issue or not.
Each TreeViewItem has an IsSelected property, and I suspect the old one isn't getting set to false. Try setting it to false whenever you set the new item to true.
var currentItem = treeView.ItemContainerGenerator
.ContainerFromItem(treeView.SelectedItem) as TreeViewItem;
currentItem.IsSelected = false;
If that doesn't work, try setting focus on the newly selected item at the same time as when you select it. Don't forget that WPF also has two focus scopes: Logical Focus and Keyboard Focus. You may need to set both.
treeViewItem.Focus(); // Sets Logical Focus
Keyboard.Focus(treeViewItem); // Sets Keyboard Focus
so, I have this ListView in grid mode. I am dynamically updating it using a CollectionView. now, the problem I have is that when I open a context menu by right clicking on an item in my grid the context menu closes after the item updates--now, it is not a new item but it is the same item. Does anyone have any ideas on how I can make the contet menu stay open after the item updates?
[Edit]
The grid is part of a public safety application that updates in near real-time. so the items are periodically added, removed, and updated. If we right-click on an item to open the context menu and an update occurs before I can close it--even if the particular item does not change in any way--the context menu closes. The desired behavior is for the context menu to remain open.
If you could supply your XAML that would help, but my guess is that you have defined the context menu on the ListViewItem element and that the menu closes because the whole ListViewItem is regenerated or replaced by WPF.
Perhaps you can define the context menu on the ListView instead? You will have to update your commands and get the selected item from the list when executing, since the context will no longer be a specific item.