I have an app that has a main window that contains a bunch of stuff. From time to time the user will do something in response to which I want to display something else entirely in the main window, temporarily hiding what is there.
I'm doing this by making the outermost element in the main window a Grid with no rows or columns defined. Every element in the grid, then will completely fill the one single cell in the grid, drawing on top of the others.
My regular bunch stuff, then, is in the first element of the grid, and my temporary something else is a UserControl as the second element of the grid, that is normally set Visibility=Collapsed.
Except for the KeyBinding everything works fine. When the appropriate command is triggered in the regular bunch of stuff, the visibility on the UserControl is set to Visible, and it covers the regular bunch of stuff completely. When the user clicks on the close button on the UserControl, it's visibility is set to Collapsed, again, and it disappears and the regular bunch of stuff is revealed.
My problem is with KeyBindings. I have a few defined on the UserControl - that should not be defined on the main window - and they don't work. Or rather, they work fine once I click inside the UserControl, but they don't work until I do.
I need them to work as soon as the UserControl is made visible, without requiring the user to click or tab into the UserControl proper.
My guess is that this has something to do with keyboard focus - but I've been unable to find a way to set the focus on the UserControl. Here's the thing - the only element within the UserControl is a tab control, all of the tabs of which are dynamically constructed via templates. There are no elements known at compile time that I can reference explicitly and pass to KeyBoard.Focus().
So, am I right in thinking that it's lack of focus that is causing the problem? And if so, how can I set focus to an element in a TabControl, when I don't even know how many tabs there are, let alone which is the selected one?
I wanted this control to have the focus, when it became visible. So in the constructor, I set up a handler on IsVisibleChanged.
public MyControl
{
...
this.IsVisibleChanged += new DependencyPropertyChangedEventHandler(MyControl_IsVisibileChanged);
}
void MyControl_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
if (!(bool(e.NewValue)
return;
this.Focusable = true;
Keyboard.Focus(this);
}
I could have set Focusable in the xaml, but I prefer it in the code-behind, so that all of the relevant code is in one place.
For me this worked in the code-behind:
using System.Windows.Input;
namespace MyApplication.Views.Dialogs
{
public partial class MyControl
{
public MyControl()
{
InitializeComponent();
Loaded += (sender, args) =>
{
MyButton.Focus();
Keyboard.Focus(MyButton);
};
}
}
}
I was wondering if there was a way to close a window when a property in the view model changes. In my situation I have a login window with an Ok button bound to a LoginCommand so that the function Login executes when Ok is clicked. If the login is successful, I want the window to close.
Now I know I could do this by adding an event handler on my button, which calls a function like this:
private void Button_Click(object sender, RoutedEventArgs e)
{
DatabaseCredentialsViewModel vm = (this.DataContext as DatabaseCredentialsViewModel);
vm.Login();
if (vm.LoginSuccessful)
{
this.Close();
}
}
But I was wondering if there was a way to close the window when LoginSuccessful property changes without having an event handler on my button (I like working only with command binding and not having event handlers on Click event).
Thank you
Here's a similar question, which filled my need.
Basically, you use an attached property for your window, which binds to a bool? property on your VM. When the VM property is set to something non-null, the attached property sets the Window's DialogResult, which will automatically close the window.
If you want you can try this different approach.
You can do this by associating the OK button with a command. Create an event such as LoginSuccess and when then add a window.Close() to the list of event callback. Then you have only to raise the LoginSuccess event to close the windows.
In my opinion, this respect the MVVM pattern defining an event that can be used for other trigger and not only for closing windows.
You could do this fairly easily by creating an attached property or Behavior (from Blend SDK) that hooked into your Window.
I posted a sample behavior to the Expression Code Gallery which does something similar (though definitely different) - it prevents a window from being closed via a property on the VM. You could very easily adapt the code (included in the download) to just close the window on a property change.
I have seen this question asked a few times but I have not seen been able to find a complete answer to my scenario.
Within my project I have a user control that I have created as a listbox item. Within this user control I have a button
<Button x:Name="DetailButton"
Grid.Column="1"
Width="107"
Height="23"
Margin="196,94,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Click="MoreDetail_Click"
Command="{Binding GetCFSDetailCommand}"
Content="View Details [+]" />
the button has a click event specific to the view this basically expands or collapses a grid row based upon the state of visibility. I used an event here since it was specific to the ui. This button also has a command which is called in the VM.
VM code
public class SearchViewModel : INotifyPropertyChanged
{
private DelegateCommand _getCFSDetailCommand;
public DelegateCommand GetCFSDetailCommand
{
get
{
if (this._getCFSDetailCommand == null)
this._getCFSDetailCommand = new DelegateCommand(GetCFSDetailCommandExecute, CanGetCFSDetailCommandExecute);
return this._getCFSDetailCommand;
}
}
private void GetCFSDetailCommandExecute(object parameter)
{
//bind collection to model call here
}
The issue I am having is the command on the button is "lost" or never called when inside the listbox item I have the view bound to the vm and if I place this command on any other button within the view the command is called. Can anyone help me understand how to call a Command bound to button within a listbox item?
Thank you in advance
randyc,
In your original (first) post you was binding the CommandParameter to a local data context of list item. In the second post you miss that binding, and I think it is impossible in the context of second port.
In your case I propose to use the Element to Element binding to bind to the GetCFSDetailCommand command from the parent data context.
The issue in calling a command within the usercontrol as a listbox item is that the pattern is looking for the command within the context of the control. Apparently the listbox item jumps outside of the visual tree and so binding is not inherited.
To correct this I needed to explicitly set the data context of the button to the ViewModel. This was ultimately solved using the Element to Element binding which allowed me to point the datacontext of the user control to the main view that contained it.
Hope this helps
I'm creating a simple editor within our application using the WPF RichTextBox. Above it I've added the reguslar buttons like Bold, Italic, etc. These buttons use the RichTextBox's commands to set these properties, but next to these buttons, the commands also get send with CTRL+B, CTRL+I, etc. I want these buttons to represent the current state of the RichTextBox at the cursor. I already found out how to get this state and it works when I update this state on the SelectionChanged event. This event ofcourse isn't fired when Bold is toggled so there is no direct feedback.
I would like to know if there is a way to listen to the commands being called, without affecting its original behaviour or some other ideas to solve my problems.
I tried listening to the command the following way:
CommandBinding boldBinding = new CommandBinding(EditingCommands.ToggleBold, CommandExecuted);
_richTextBox.CommandBindings.Add(boldBinding);
and
private void CommandExecuted(object sender, ExecutedRoutedEventArgs e) {
UpdateProperties();
e.Handled = false;
}
This did update the properties, but the RichTextBox didn't seem to receive the command anymore.
I also tried to make my own commands on the control containing the RichTextBox, but when CTRL+B is pressed when the RichTextBox has focus, the original RichTextBox commands are called instead of the new one.
Many thanks in advance!
Liewe
In order to listen to the commands being called, you can use the events raised by CommandManager: Executed or PreviewExecuted.
If you change your XAML to:
<RichTextBox x:Name="_richTextBox" ...
CommandManager:PreviewExecuted="OnRichTextBoxCommand" ... />
you get the OnRichTextBoxCommand method called right before the command is executed. Unfortunately, using the Executed attached event does not work.
This method is called for each event, so you have to filter them:
private void OnRichTextBoxCommand(object sender, ExecutedRoutedEventArgs e) {
if (e.Command == EditingCommands.ToggleBold) {
UpdateProperties();
}
}
It may be even a bit more complex, as the current selection may not have changed when this method is called, so you have to post yourself a message, e.g. like this:
Dispatcher.BeginInvoke(new Action(UpdateProperties));
(if you reference already System.Core, you have the Action type, otherwise define a delegate taking no parameter and returning void, and use in instead.)
I have a UserControl which contains a TextBox. When my main window loads I want to set the focus to this textbox so I added Focusable="True" GotFocus="UC_GotFocus" to the UserControls definition and FocusManager.FocusedElement="{Binding ElementName=login}" to my main windows definition. In the UC_GotFocus method i simply call .Focus() on the control i want to focus on but this doesn't work.
All i need to do is have a TextBox in a UserControl receive focus when the application starts.
Any help would be appreciated, thanks.
I recently fixed this problem for a login splash screen that is being displayed via a storyboard when the main window is first loaded.
I believe there were two keys to the fix. One was to make the containing element a focus scope. The other was to handle the Storyboard Completed event for the storyboard that was triggered by the window being loaded.
This storyboard makes the username and password canvas visible and then fades into being 100% opaque. The key is that the username control was not visible until the storyboard ran and therefore that control could not get keyboard focus until it was visible. What threw me off for awhile was that it had "focus" (i.e. focus was true, but as it turns out this was only logical focus) and I did not know that WPF had the concept of both logical and keyboard focus until reading Kent Boogaart's answer and looking at Microsoft's WPF link text
Once I did that the solution for my particular problem was straightforward:
1) Make the containing element a focus scope
<Canvas FocusManager.IsFocusScope="True" Visibility="Collapsed">
<TextBox x:Name="m_uxUsername" AcceptsTab="False" AcceptsReturn="False">
</TextBox>
</Canvas>
2) Attach a Completed Event Handler to the Storyboard
<Storyboard x:Key="Splash Screen" Completed="UserNamePassword_Storyboard_Completed">
...
</Storyboard>
and
3) Set my username TextBox to have the keyboard focus in the storyboard completed event handler.
void UserNamePassword_Storyboard_Completed(object sender, EventArgs e)
{
m_uxUsername.Focus();
}
Note that calling item.Focus() results in the call Keyboard.Focus(this), so you don't need to call this explicitly. See this question about the difference between Keyboard.Focus(item) and item.Focus.
Its stupid but it works:
Pop a thread that waits a while then comes back and sets the focus you want. It even works within the context of an element host.
private void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
System.Threading.ThreadPool.QueueUserWorkItem(
(a) =>
{
System.Threading.Thread.Sleep(100);
someUiElementThatWantsFocus.Dispatcher.Invoke(
new Action(() =>
{
someUiElementThatWantsFocus.Focus();
}));
}
);
}
Just recently I had a list-box that housed some TextBlocks. I wanted to be able to double click on the text block and have it turn into a TextBox, then focus on it and select all the text so the user could just start typing the new name (Akin to Adobe Layers)
Anyway, I was doing this with an event and it just wasn't working. The magic bullet for me here was making sure that I set the event to handled. I figure it was setting focus, but as soon as the event went down the path it was switching the logical focus.
The moral of the story is, make sure you're marking the event as handled, that might be your issue.
“When setting initial focus at application startup, the element to
receive focus must be connected to a PresentationSource and the
element must have Focusable and IsVisible set to true. The recommended
place to set initial focus is in the Loaded event handler"
(MSDN)
Simply add a "Loaded" event handler in the constructor of your Window (or Control), and in that event handler call the Focus() method on the target control.
public MyWindow() {
InitializeComponent();
this.Loaded += new RoutedEventHandler(MyWindow_Loaded);
}
void MyWindow_Loaded(object sender, RoutedEventArgs e) {
textBox.Focus();
}
since i tried a fuzquat's solution and found it the most generic one, i thought i'd share a different version, since some complained about it looking messy. so here it is:
casted.Dispatcher.BeginInvoke(new Action<UIElement>(x =>
{
x.Focus();
}), DispatcherPriority.ApplicationIdle, casted);
no Thread.Sleep, no ThreadPool. Clean enough i hope.
UPDATE:
Since people seem to like pretty code:
public static class WpfExtensions
{
public static void BeginInvoke<T>(this T element, Action<T> action, DispatcherPriority priority = DispatcherPriority.ApplicationIdle) where T : UIElement
{
element.Dispatcher.BeginInvoke(priority, action);
}
}
now you can call it like this:
child.BeginInvoke(d => d.Focus());
WPF supports two different flavors of focus:
Keyboard focus
Logical focus
The FocusedElement property gets or sets logical focus within a focus scope. I suspect your TextBox does have logical focus, but its containing focus scope is not the active focus scope. Ergo, it does not have keyboard focus.
So the question is, do you have multiple focus scopes in your visual tree?
I found a good series of blog posts on WPF focus.
Part 1: It’s Basically Focus
Part 2: Changing WPF focus in code
Part 3: Shifting focus to the first available element in WPF
They are all good to read, but the 3rd part specifically deals with setting focus to a UI element in a UserControl.
Set your user control to Focusable="True" (XAML)
Handle the GotFocus event on your control and call yourTextBox.Focus()
Handle the Loaded event on your window and call yourControl.Focus()
I have a sample app running with this solution as I type. If this does not work for you, there must be something specific to your app or environment that causes the problem. In your original question, I think the binding is causing the problem.
I hope this helps.
After having a 'WPF Initial Focus Nightmare' and based on some answers on stack, the following proved for me to be the best solution.
First, add your App.xaml OnStartup() the followings:
EventManager.RegisterClassHandler(typeof(Window), Window.LoadedEvent,
new RoutedEventHandler(WindowLoaded));
Then add the 'WindowLoaded' event also in App.xaml :
void WindowLoaded(object sender, RoutedEventArgs e)
{
var window = e.Source as Window;
System.Threading.Thread.Sleep(100);
window.Dispatcher.Invoke(
new Action(() =>
{
window.MoveFocus(new TraversalRequest(FocusNavigationDirection.First));
}));
}
The threading issue must be use as WPF initial focus mostly fails due to some framework race conditions.
I found the following solution best as it is used globally for the whole app.
Hope it helps...
Oran
I converted fuzquat's answer to an extension method. I'm using this instead of Focus() where Focus() did not work.
using System;
using System.Threading;
using System.Windows;
namespace YourProject.Extensions
{
public static class UIElementExtension
{
public static void WaitAndFocus(this UIElement element, int ms = 100)
{
ThreadPool.QueueUserWorkItem(f =>
{
Thread.Sleep(ms);
element.Dispatcher.Invoke(new Action(() =>
{
element.Focus();
}));
});
}
}
}
I've noticed a focus issue specifically related to hosting WPF UserControls within ElementHosts which are contained within a Form that is set as an MDI child via the MdiParent property.
I'm not sure if this is the same issue others are experiencing but you dig into the details by following the link below.
Issue with setting focus within a WPF UserControl hosted within an ElementHost in a WindowsForms child MDI form
I don't like solutions with setting another tab scope for UserControl. In that case, you will have two different carets when navigating by keyboard: on the window and the another - inside user control. My solution is simply to redirect focus from user control to inner child control. Set user control focusable (because by default its false):
<UserControl ..... Focusable="True">
and override focus events handlers in code-behind:
protected override void OnGotFocus(RoutedEventArgs e)
{
base.OnGotFocus(e);
MyTextBox.Focus();
}
protected override void OnGotKeyboardFocus(KeyboardFocusChangedEventArgs e)
{
base.OnGotKeyboardFocus(e);
Keyboard.Focus(MyTextBox);
}
What did the trick for me was the FocusManager.FocusedElement attribute. I first tried to set it on the UserControl, but it didn't work.
So I tried putting it on the UserControl's first child instead:
<UserControl x:Class="WpfApplication3.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid FocusManager.FocusedElement="{Binding ElementName=MyTextBox, Mode=OneWay}">
<TextBox x:Name="MyTextBox"/>
</Grid>
... and it worked! :)
I have user control - stack panel with two text boxes.The text boxes were added in contructor, not in the xaml. When i try to focus first text box, nothing happend.
The siggestion with Loaded event fix my problem. Just called control.Focus() in Loaded event and everthing.
Assuming you want to set focus for Username textbox, thus user can type in directly every time it shows up.
In Constructor of your control:
this.Loaded += (sender, e) => Keyboard.Focus(txtUsername);
After trying combinations of the suggestions above, I was able to reliably assign focus to a desired text box on a child UserControl with the following. Basically, give focus to the child control and have the child UserControl give focus to its TextBox. The TextBox's focus statement returned true by itself, however did not yield the desired result until the UserControl was given focus as well. I should also note that the UserControl was unable to request focus for itself and had to be given by the Window.
For brevity I left out registering the Loaded events on the Window and UserControl.
Window
private void OnWindowLoaded(object sender, RoutedEventArgs e)
{
ControlXYZ.Focus();
}
UserControl
private void OnControlLoaded(object sender, RoutedEventArgs e)
{
TextBoxXYZ.Focus();
}
I set it in the PageLoaded() or control loaded, but then I'm calling WCF async service and doing stuff that seems to lose the focus. I have to to set it at the end of all the stuff I do. That's fine and all, but sometimes I make changes to the code and then I forget that I'm also setting the cursor.
I had same problem with setting keyboard focus to canvas in WPF user control.
My solution
In XAML set element to Focusable="True"
In element_mousemove event create simple check:
if(!element.IsKeyBoardFocused)
element.Focus();
In my case it works fine.