I must be missing something obvious - how can I detect when a node is expanded in a Silverlight TreeView?
Also the treeviewitems have an expanded event which I'm using currently but you'd have to attach to each node you add.
AddHandler t.Expanded, AddressOf TreeViewItem_Expanded
Unfortunately "SelectedItemChanged" is not a routed event yet. So the closest you could get is using this:
treeView.AddHandler(TreeView.MouseLeftButtonUpEvent, new MouseButtonEventHandler(OnMouseLeftButtonUp), true);
void OnMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
if (e.OriginalSource is Path)
{
Path p = e.OriginalSource as Path;
if (p.Name == "CheckedVisual" || p.Name == "UncheckedVisual")
{
}
}
}
Related
I have code where I can take a look at the SelectedItem and then output ToString() to get the record into the clipboard.
How can I detect what cell the user is right clicking on in order to copy just that cell in the SelectedItem?
For example, if I have Borrower Information and the user right-clicks on last name, I would like to give the ability to just copy last name to clipboard.
Thank you!
UPDATE:
Here is the code that I used as suggested by Josh, it worked great:
private void BorrowerInfoCopyClicked(object sender, RoutedEventArgs e)
{
BorrowerViewModel vm = this.DataContext as BorrowerViewModel;
if (vm != null)
{
Clipboard.SetData(DataFormats.Text, vm.CurrentTextBlockText);
}
}
private void AddressCopyClicked(object sender, RoutedEventArgs e)
{
BorrowerViewModel vm = this.DataContext as BorrowerViewModel;
if (vm != null)
{
Clipboard.SetData(DataFormats.Text, vm.CurrentTextBlockText);
}
}
private void lstViews_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
BorrowerViewModel vm = this.DataContext as BorrowerViewModel;
if (vm != null)
{
if (e.OriginalSource is TextBlock)
{
TextBlock txtBlock = e.OriginalSource as TextBlock;
vm.CurrentTextBlockText = txtBlock.Text;
}
}
}
I've done this by handling the PreviewMouseRightButtonDown event on the ListView and checking if e.OriginalSource is a TextBlock. If so, copy the txtBlk.Text to the clipboard. This code could either be in the code-behind of the View that contains the ListView, or as a behavior you attach to the ListView. If you need to use a context menu to perform the Copy operation, have a TextBlock field that you use to store a reference to the TextBlock, and in your method that responds to a MenuItem's click (or Command execution) reference the TextBlock there instead.
I have a ListBox and a DockPanel. List box contains items that are supposed to be dragged onto the dock panel. I've implemented that by following this link.
There are a couple of things I do not understand though:
While dragging, all I see is a cursor. I'd like to literary see the list item I am
dragging to move around with my cursor. How do I do that?
Is the DragDropEffect property only for the different cursor design or it has a
higher purpose? :)
How do I make list item disappear from the ListBox once it is dropped onto the
DockPanel?
I'd like to enforce some animation on the items that I drag, like glow once it is
dropped. Which trigger/setter should I use for that?
Here's my code for basic dragging and dropping:
Code-behind for the ListBox part
private Point startPosition;
private void ListBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
startPosition = e.GetPosition(null);
}
private void ListBox_PreviewMouseMove(object sender, MouseEventArgs e)
{
Point currentPosition;
Vector offset;
ListBox listBox;
ListBoxItem item;
Match match;
DataObject dragData;
currentPosition = e.GetPosition(null);
offset = startPosition - currentPosition;
if (e.LeftButton == MouseButtonState.Pressed &&
(Math.Abs(offset.X) > SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(offset.Y) > SystemParameters.MinimumVerticalDragDistance))
{
// Get the data binded to ListBoxItem object, which is "match"
listBox = sender as ListBox;
item = FindAnchestor<ListBoxItem>((DependencyObject)e.OriginalSource);
match = (Match)listBox.ItemContainerGenerator.ItemFromContainer(item);
dragData = new DataObject("match", match);
DragDrop.DoDragDrop(item, dragData, DragDropEffects.Move);
}
}
Code-behind for the DockPanel part
private void DockPanel_DragEnter(object sender, DragEventArgs e)
{
if (!e.Data.GetDataPresent("match") ||
sender == e.Source)
{
e.Effects = DragDropEffects.None;
}
}
private void DockPanel_Drop(object sender, DragEventArgs e)
{
Match match;
DockPanel matchSlot;
ContentPresenter contentPresenter;
Binding binding;
if (e.Data.GetDataPresent("match"))
{
match = e.Data.GetData("match") as Match;
matchSlot = sender as DockPanel;
contentPresenter = new ContentPresenter();
contentPresenter.ContentTemplate = this.FindResource("MatchTemplate") as DataTemplate;
binding = new Binding();
binding.Source = match;
contentPresenter.SetBinding(ContentPresenter.ContentProperty, binding);
matchSlot.Children.Clear();
matchSlot.Children.Add(contentPresenter);
}
}
Thanks for all the help.
Ok, after a while I found some answers and discovered a few things on my own.
As for the DragDropEffect enum, it should be used for two reasons:
To distinguish if the item is moved or copied in the code. It serves like a flag and should be used most commonly like this:
if (e.DragDropEffect == DragDropEffect.Move)
{
...
}
else ...
To decorate the mouse cursor based on the enum value. This way it tells the user if he or she is moving or copying the item.
As for the drag and drop visualization here's a link to the post containing the reference which is an excellent starting point for drag and drop to build on: WPF Drag & Drop: How to literally drag an element?
How to determine on over which node click was performed?
Treeview from silverlight toolkit.
In MouseRightButtonUp i need to get node:
private void treeView_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
The MouseButtonEventArgs has an OriginalSource property which indicates the actual UIElement that generated the event.
In order to discover which Node that element belongs to you will need to traverse the visual tree to discover it. I use this extension method to assist with that:-
public static IEnumerable<DependencyObject> Ancestors(this DependencyObject root)
{
DependencyObject current = VisualTreeHelper.GetParent(root);
while (current != null)
{
yield return current;
current = VisualTreeHelper.GetParent(current);
}
}
Then in the MouseRightButtonUp event you can use this code to find the item:-
TreeViewItem node = ((DependencyObject)e.OriginalSource)
.Ancestors()
.OfType<TreeViewItem>()
.FirstOrDefault();
I want to add a simple (at least I thought it was) behaviour to my WPF TextBox.
When the user presses Escape I want the TextBox he is editing to have the text it had when the user started editing, AND I want to remove the focus from the TextBox.
I don't have any problem setting the text for the value it had in the beginning of the edit.
The problem is to remove the focus of the element. I don't want to move the focus to any other component, I just want the TextBox to lose focus. Will I have to have an invisible element to set the focus so my TextBox can lose focus?
in .NET Framework 4 just Keyboard.ClearFocus();
The code I have been using :
// Move to a parent that can take focus
FrameworkElement parent = (FrameworkElement)textBox.Parent;
while (parent != null && parent is IInputElement && !((IInputElement)parent).Focusable)
{
parent = (FrameworkElement)parent.Parent;
}
DependencyObject scope = FocusManager.GetFocusScope(textBox);
FocusManager.SetFocusedElement(scope, parent as IInputElement);
Since none of the above answers worked for me and the accepted answer does work only for a keyboard focus, I came to the following approach:
// Kill logical focus
FocusManager.SetFocusedElement(FocusManager.GetFocusScope(textBox), null);
// Kill keyboard focus
Keyboard.ClearFocus();
Kills both, logical as well as the keyboard focus.
A bit late to the party, but it was helpful to me so here it goes.
Since .Net 3.0, FrameworkElement has a MoveFocus function which did the trick for me.
You can set the focus to a focusable ancestor. This code will work even if the textbox is inside a template with no focusable ancestors inside that same template:
DependencyObject ancestor = textbox.Parent;
while (ancestor != null)
{
var element = ancestor as UIElement;
if (element != null && element.Focusable)
{
element.Focus();
break;
}
ancestor = VisualTreeHelper.GetParent(ancestor);
}
AFAIK, it is not possible to completely remove the focus. Something in your Window will always have the focus.
For me, it's quite tricky, especially when using with LostFocus binding.
However, my workaround is to add an empty label and focus on it.
<Label Name="ResetFocusArea" Focusable="True" FocusVisualStyle="{x:Null}" />
...
OnKeyDown(object sender, RoutedEventArgs e)
{
//if is Esc
ResetFocusArea.Focus();
}
Using LPL's answer worked for me, but it would also make me unable to select any options in dropdown menues. To combat this, I added a check to see if the focused element was a textbox.
Doing the same check for when pressing enter, my final code looked like this:
public Menu()
{
InitializeComponent();
this.PreviewMouseDown += PreviewMouseDownEventHandler;
this.KeyDown += WindowKeyDownHandler;
}
void ClearFocus()
{
UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;
if (elementWithFocus is System.Windows.Controls.TextBox tb)
{
if (Keyboard.FocusedElement != null)
{
Keyboard.FocusedElement.RaiseEvent(new RoutedEventArgs(UIElement.LostFocusEvent));
Keyboard.ClearFocus();
}
}
}
private void PreviewMouseDownEventHandler(object sender, MouseButtonEventArgs e)
{
ClearFocus();
}
private void WindowKeyDownHandler(object sender, System.Windows.Input.KeyEventArgs e)
{
if (e.Key == Key.Enter)
{
ClearFocus();
}
}
With this, I didn't need to add a focuslost to every textbox, and it can easily extend to other elements without breaking compatability with other parts of the program.
In Windows Phone Development, I just did Focus() or this.Focus() in the PhoneApplicationPage and it worked like a charm.
My answer does not adress the above question directly, however, I feel that the wording of it has caused it to become "The Question" about programmatically getting rid of focus. A common scenario where this is needed is for the user to be able to clear focus upon left-clicking the background of a root control, like window.
So, to achieve this, you can create an Attached Behavior that will switch focus to a dynamically created control (in my case, an empty label). It is preferrable to use this behavior on the highest-level elements like windows, as it iterates through it's children to find a panel it can add a dummy label to.
public class LoseFocusOnLeftClick : Behavior<FrameworkElement>
{
private readonly MouseBinding _leftClick;
private readonly Label _emptyControl = new Label() { Focusable = true, HorizontalAlignment = HorizontalAlignment.Left, VerticalAlignment = VerticalAlignment.Top };
public LoseFocusOnLeftClick()
{
_leftClick = new MouseBinding(new RelayCommand(LoseFocus), new MouseGesture(MouseAction.LeftClick));
}
protected override void OnAttached()
{
AssociatedObject.InputBindings.Add(_leftClick);
AssociatedObject.Loaded += AssociatedObject_Loaded;
}
protected override void OnDetaching()
{
AssociatedObject.InputBindings.Remove(_leftClick);
AssociatedObject.Loaded -= AssociatedObject_Loaded;
}
private void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
{
AssociatedObject.Loaded -= AssociatedObject_Loaded;
AttachEmptyControl();
}
private void AttachEmptyControl()
{
DependencyObject currentElement = AssociatedObject;
while (!(currentElement is Panel))
{
currentElement = VisualTreeHelper.GetChild(currentElement, 0);
}
((Panel)currentElement).Children.Add(_emptyControl);
}
private void LoseFocus()
{
_emptyControl.Focus();
}
}
If you want to remove focus from a certain TextBox, just add this line..
textBox.Focusable = false;
I admit, it is kind of tiny, but I am looking for better ways to do the following code blocks. They should be self explaining...
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
var listBoxItem = sender as ListBoxItem;
if (listBoxItem != null)
{
var clickObject = listBoxItem.DataContext as ClickObject;
if (clickObject != null)
{
clickObject.SingleClick();
}
}
}
Another ugly one:
private void listBox_SelectionChangedA(object sender, SelectionChangedEventArgs e)
{
var lB = sender as ListBox;
if (lB != null)
StatusBoxA.Text = "Elements selected" + lB.SelectedItems.Count;
}
Yeah, I know, its not near-death-urgent. But I do NOT like the (if != null). Any magic ideas to shorten it even more :-)
Btw, I found some nice info about a similar topic: Loops on Null Items
Nice to read...
I love good, clean code but in most cases, clean & elegant doesn't mean short and smart. Code brevity is good for competitions. Changing an "if not null" statement to a foreach might seem way cooler but it's harder for everyone else working in the project to understand what you are trying to accomplish. Believe me, even you won't remember it a few months later :P. Your code is just fine as it is!
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
var listBoxItem = sender as ListBoxItem;
if (listBoxItem == null) return;
var clickObject = listBoxItem.DataContext as ClickObject;
if (clickObject == null) return;
clickObject.SingleClick();
}
One-liner:
private void listBox_SelectionChangedA(object sender, SelectionChangedEventArgs e)
{
As<ListBox>(sender, (lB) => StatusBoxA.Text = "Elements selected" + lB.SelectedItems.Count);
}
or, nested:
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
As<ListBoxItem>(sender, (listBoxItem) => {
As<ClickObject>(listBoxItem.DataContext,
(clickObject) => clickObject.SingleClick());
};
}
using this static generic method (T is destination type, input is object to cast, code is a delegate (or lambda expression) to execute on success:
static void As<T>(object input, Action<T> code) where T : class
{
T foo = input as T;
if (foo != null)
code(foo);
}
Since you're using known events from the .NET framework (as opposed to a third party) and from the code it looks like you're only using those methods for specific classes (i.e. ListBoxItems and ListBoxes), there are a few things you know to be true:
sender will never be null
sender will always be a ListBoxItem, or ListBox, respectively
So why use the as operator? Just cast!
Then the first snippet becomes
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
var listBoxItem = (ListBoxItem)sender;
var clickObject = (ClickObject)listBoxItem.DataContext;
clickObject.SingleClick();
}
Note this isn't true in the general case (you wouldn't do this if you were handling all PreviewMouseDown events in that one handler for all Control types), but for event handling code like this, especially in UI code, you can be as certain as you can be of anything, that sender will not be null and sender will be of the type you expect.
Maybe I am just being pedantic but why do you need to cast the sender if you are using the event within its host containers code.
Regardless of who made the change to a list, couldn't you just give your listbox a name and use that.
<ListBox x:Name="listbox1" />
private void listBox_SelectionChangedA(object sender, SelectionChangedEventArgs e)
{
StatusBoxA.Text = "Elements selected" + listbox1.SelectedItems.Count;
}
Or you could even achieve some of this using binding with no code behind.
This is supposed to be the same as the first one, reformatted a little:
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
ClickObject clickObject;
if (
((sender as ListBoxItem) != null) &&
((clickObject = ((ListBoxItem)sender).DataContext as ClickObject) != null)
)
{
clickObject.SingleClick();
}
}
You can add extensions methods to Form elements, which can then trigger the events:
public static void OnSelectionChanged(this ListBox b, Action<ListBox> a)
{
b.SelectedIndexChanged += (s,e) =>
{
if (s is ListBox)
a(s as ListBox);
};
}
Using the same idea as Utaal's solution, but as an extension method...
public static void As<TSource>(this object item, Action<TSource> action) where TSource : class
{
var cast = item as TSource;
if (cast != null)
action(cast);
}
private void listBoxItem_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
sender.As<ListBoxItem>(listBoxItem =>
listBoxItem.DataContext.As<ClickObject>(clickObject =>
clickObject.SingleClick()));
}