I'm trying to create an attached behavior to add an auto-complete list to the standard TextBox control. My goal is that every time the TextChanged event is raised, my AutoCompleteBehavior class creates a popup and fills it with potential auto-complete results.
To get these results, my AutoCompleteBehavior declares the following event:
Public Shared ReadOnly AutoCompleteListRequestedEvent As RoutedEvent =
EventManager.RegisterRoutedEvent("AutoCompleteListRequested",
RoutingStrategy.Bubble,
GetType(AutoCompleteListRequestedEventHandler), GetType(AutoCompleteBehavior))
The above is meant to be an attached event, used like this:
<TextBox lib:AutoCompleteBehavior.AutoCompleteListRequested="EventHandlerHere"/>
The idea is that when TextChanged is raised, AutoCompleteBehavior.AutoCompleteListRequested is also raised, which asks the implementing program to supply a list of suggestions for the current input.
For this to work, I have to hook in to the TextBox.TextChanged event as soon as my attached event is attached to said TextBox. Per Microsoft I should be able to declare a sub Add*Handler and Remove*Handler where the "*" is the name of the attached event, and these would be called whenever the attached event is added or removed from an element.
So right below the event declaration I have:
Public Shared Sub AddAutoCompleteListRequestedHandler(TB As TextBox, handler As AutoCompleteListRequestedEventHandler)
'Code to hook into TextBox.TextChanged
End Sub
Public Shared Sub RemoveAutoCompleteListRequestedHandler(TB As TextBox, handler As AutoCompleteListRequestedEventHandler)
'Code to unhook fromTextBox.TextChanged
End Sub
My problem is AddAutoCompleteListRequestedHandler is never called. If I call TextBox.RaiseEvent to raise AutoCompleteListRequested, the event handler defined in XAML does get called (so the event is attached), but it seems my AddAutoCompleteListRequestedHandler is completely skipped.
As a final note, I found this question here which seems to be describing the same problem (my code is also in a dll just like his), but it's two years old and was never answered.
The XAML processor won't call your static methods when hooking up the event handler.
If you want to do something when the TextBox raises the TextChanged event, you would probably be better off implementing an attached behaviour and hook up to the TextChanged event in the PropertyChangedCallback or in the OnAttached() method depending on which kind of behaviour you create.
Please refer to my answer here for more information about attached behaviours.
I have some RoutedCommands for commands like control-A, copy paste and they all work fine.
Then I added 4 more routedcommands to move object up down left and right in the canvas using arrowkeys, they sometimes works and sometime doesn't. At first I thought it was a Focus issue on the Canvas but I just found out that at the same time, all the other routedcommands like control-A works but arrowkeys doesn't.
I really have no idea what's going on here, they are identical routedcommands with different variable names, how come one works 100% of time and one only work 50% of time?
Working RoutedCommand:
_bindings.Add(new CommandBinding(DesignerCanvas.SelectAll, SelectAll_Executed));
SelectAll.InputGestures.Add(new KeyGesture(Key.A, ModifierKeys.Control));
private void SelectAll_Executed(object sender, ExecutedRoutedEventArgs e)
{
SelectionService.SelectAll();
}
Malfunctioning RoutedCommand:
_bindings.Add(new CommandBinding(DesignerCanvas.MoveDown, MoveDown_Executed));
MoveDown.InputGestures.Add(new KeyGesture(Key.Down));
private void MoveDown_Executed(object sender, ExecutedRoutedEventArgs e)
{
e.Handled = true;
var selectedItems = from item in SelectionService.CurrentSelection.OfType<DesignerItem>()
select item;
if (selectedItems.Count() > 0)
{
for (int i = 0; i < selectedItems.Count(); i++)
selectedItems.ElementAt(i).Top += Option.OptionSingleton.Sensitivity;
}
}
The malfunctioning RoutedCommand is just not firing sometimes, especially after I open some other window and come back to the canvas, then it will stop firing while other routedcommands are unaffected. Any ideas what's causing this weird behavior?
You can sometiems use very inclusive class event handlers to trace the route of an event:
EventManager.RegisterClassHandler(typeof(FrameworkElement), CommandManager.CanExecuteEvent,
new CanExecuteRoutedEventHandler((s, e) => Debug.WriteLine("CanExecute: " + s)), true);
EventManager.RegisterClassHandler(typeof(FrameworkElement), CommandManager.ExecutedEvent,
new CanExecuteRoutedEventHandler((s, e) => Debug.WriteLine("Executed:" + s)), true);
EventManager.RegisterClassHandler(typeof(FrameworkElement), CommandManager.ExecutedEvent,
new CanExecuteRoutedEventHandler((s, e) => Debug.WriteLine("KeyDown:" + s)), true);
In your case the KeyDown may be handled before it reaches the command binding or the CanExecute event may not reach it for some other reason.
Hopefully this will help you debug the problem
This may be due to the fact that the key you are using is the "Down" key. I suspect that if you used a different key, it would work.
Some controls consume the arrow keys and pageup/pagedown keys. For example, TextBox does this. If your Canvas is in a scrollviewer, the scrollviewer might be eating it.
There are two workarounds for this:
Add a binding to the control that is eating the key gesture.
Handle KeyPreview for the Canvas (or any parent of the control that is eating the keystroke) and execute the command from there.
The answer to this question shows how you can do #2 without writing specific code in the KeyPreview handler for each command.
It turns out that it was a focus issue, I just set the focus to the canvas whenever mouse enters, now it's sort of fixed. Thanks everybody for answering.
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.)
is there a way I can get a Load event for System.Windows.Forms.Control just like System.Windows.Forms.Form.Load?
I want to run some initialize code before the control first shown.
Also, it would be nice to be able to do the same for System.Windows.Forms.ToolStripStatusLabel which is not actually a Control, but works like one.
Ideally, I can do this:
control.OnLoad(() => { dosomething here; });
in which OnLoad is a extension method that would run the argument Action when the "control" "Loads".
Thanks!
Form.Load event is called by the OnLoad method which is called from the OnCreateControl method which belongs to the Control class. So for the form the calling sequence would be following:
OnCreateControl start
OnLoad start
Form Load event call
OnLoad finish
OnCreateControl finish
I guess you can override OnCreateControl for your component and add your optimization code there.
Hope this helps, Regards.
For a control you can override either OnControlCreated or OnHandleCreated. The latter one can fire multiple times if it is necessary to recreate the control window. Be sure to use it if your code affects the window itself. In other words, if you do anything that requires the Handle property.
Few suitable choices for a ToolStripItem derived control. I'd recommend overriding SetVisibleCore() or OnAvailableChanged() or the AvailableChanged event. They run when the Visible property of the ToolStripItem changes. Beware that it may fire multiple times, keep a bool field that tracks that your initialization code has already run.
Last but not least, be sure to only do any of this if your code actually requires the control to be created. The vast majority of init code can go in the constructor. You only need a Load event if your code depends on the actual Location and Size of the control. Which might be different from the designer value if the form rescales itself due to a different system font or video DPI setting on the target machine.
I needed a solution like this for a TabPage within a TabControl.The only thing I came up with was using the paint event handler. I added the event handler for Paint and in the very first line I remove the event handler and then do more initialization code. This only works if you do nothave any custom painting. Alternatively, if you do need to do custom painting you could add a flag to check for each time Paint Executes.
//Paint only runs once
private void tabPage1_Paint(object sender, PaintEventArgs e)
{
tabPage1.Paint -= tabPage1_Paint;
//Do initialization here
}
/////////////////////////////////////////////////////////////////////////////////
//Paint always runs
private bool IsFirstPaint = true;
private void tabPage1_Paint(object sender, PaintEventArgs e)
{
if(IsFirstPaint)
{
IsFirstPaint = false;
//Do initialization here
}
//Do custom painting here
}
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.