I have seen a few posts addressing how to remove an UserControl that has been added during runtime, but my problem is a little different. I have a UserControl that consists of an image with a small "x" button on the top right corner that is used to remove itself (the UserControl) from its parent canvas. Also to note is that the UserControl is added during runtime when the user doubleclicks on a ListboxItem. I have a Click event handler for the top right corner button but this code is not running at all. I know this because I have a breakpoint in this code which is not reached when I click the button.
So,
Why isn't the click event of the remove button being handled?
Maybe there is a better way to implement this. Please advise.
Here's the code used for adding it:
private void MyListBox_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if (e.OriginalSource.ToString() == "System.Windows.Controls.Border" || e.OriginalSource.ToString() == "System.Windows.Controls.Image" || e.OriginalSource.ToString() == "System.Windows.Controls.TextBlock")
{
Expression.Blend.SampleData.MyCollection.Dataset lbi = ((sender as ListBox).SelectedItem as Expression.Blend.SampleData.MyCollection.Dataset);
var new_usercontrol = new MyUserControl();
new_usercontrol.MyImageSourceProperty = lbi.Image;
MyCanvas.Children.Add(new_usercontrol);
Canvas.SetLeft(new_usercontrol, 100);
Canvas.SetTop(new_usercontrol, 100);
Canvas.SetZIndex(new_usercontrol, 100);
}
}
The following is the cs code for the UserControl:
public partial class ModuleElement : UserControl
{
public ImageSource MyProperty
{
get { return (ImageSource)this.image.Source; }
set { this.image.Source = value; }
}
public ModuleElement()
{
this.InitializeComponent();
}
private void RemoveButton_Click(object sender, RoutedEventArgs e)
{
((Canvas)this.Parent).Children.Remove(this);
}
}
The XAML:
<Grid x:Name="LayoutRoot">
<Image x:Name="image" />
<Button x:Name="RemoveButton" Content="X" HorizontalAlignment="Right" Height="17.834" Margin="0" VerticalAlignment="Top" VerticalContentAlignment="Center" HorizontalContentAlignment="Center" Click="RemoveButton_Click">
</Button>
</Grid>
Thanks in advance,
Bryan
So I tried your code here exactly except for some name changes and could not reproduce your issue. In my personal experience your issue here has to be that for some reason the event for the click isn't subscribed to properly. For this I would go into designer for the user control, wipe out the current event for the button and double click in the designer event textbox such that VS or Blend generates all the code necessary for a proper subscription.
I have created a sample based on your code here. Feel free to pull it down and take a look to see if you can find any inconsistencies.
As far as a better way to implement this, check out the good old MVVM pattern and the MVVM Light Toolkit. With this you can have a central ViewModel class that will handle all of your button commands and binding without code behind.
Could you help me find the error in this one: The event triggers before even the windows form is loaded. I start to see the message Box and then I click OK,after that it loads the main screen.After that everything works perfectly, I wonder what triggers the ComboBox SelectionChanged Event before even loading the window.The FillComboBoxFamilyData(SegmentCode) just creates a dataset and puts the values int he ComboBox. Please Refer to this link for complete code.
Not able to make cascading comboboxes work
Any help would be highly appreciated.Thanks.
<ComboBox Height="23" HorizontalAlignment="Left" Margin="35,26,0,0" Name="comboBox1" VerticalAlignment="Top" Width="205" ItemsSource="{Binding Source={StaticResource tblSegmentViewSource}}" DisplayMemberPath="Segment Name" SelectedValuePath="Segment Code" SelectionChanged="comboBox1_SelectionChanged"/>
<ComboBox Margin="304,26,395,93" Name="comboBox2" />
private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
MessageBox.Show(comboBox1.SelectedValue.ToString());
SegmentCode = Convert.ToInt32(comboBox1.SelectedValue.ToString());
FillComboBoxFamilyData(SegmentCode);
}
At the moment the data will be loaded (attached by the binding), SelectionChanged will be fired. Therefore, you have to check in your event-handler if your app is ready and all the data is loaded and attached. If not, return the event-handler without doing anything. This behaviour is by design.
ItemsSource="{Binding Source={StaticResource tblSegmentViewSource}}"
You can use the IsLoaded-property to detect, if the binding already has been evaluated. IsLoaded will not be true unless the databinding-engine has evaluated your xaml-bindings.
private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e) {
if(!IsLoaded){
return;
}
.... your code here
You can use IsLoaded property of the combo box to test whether it is loaded yet. This is the cleanest and easiest solution which I could find:
var comboBox = (ComboBox)sender;
if (!comboBox.IsLoaded)
{
// This is when the combo box is not loaded yet and the event is called.
return;
}
I know this is an old question but I came across it twice trying to fix this in my project and had the same results as the OP. My list is populated after the IsLoaded is true. So, I figured I would post what I figured out for others. Just use the DropDowOpened event to set a bool to true. This way the SelectionChanged event won't fire until the user actually clicks on the dropdown.
private bool UserSeriesChange;
private void comboBox1_DropDownOpened(object sender, EventArgs e)
{
UserSeriesChange = true;
}
private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if(!UserSeriesChange){
return;
}
.... your code here
I had this same problem and I found out that setting the starting-selection-index of the combox using xaml will trigger the selectionchanged event when program is loading which causes the error.
To solve you can either set the selection-index to -1 (the default) OR change the current-selection-index of the combobox using code after the program has loaded.
When trying to use a Slider control I'd like to listen to the MouseLeftButtonDown and MouseLeftButtonUp. I have handlers set up for both events. The MouseLeftButtonUp works as expected. MouseLeftButtonDown is not raised at all.
Any ideas why?
I've done a bit of googling and it seems that the WPF doesn't fire either. One of the solutions (in this post) was to use the Preview version of the events which is something silverlight doesn't support.
Is there any simple solution to this that I'm not seeing?
Thanks
J
It happens because Slider handles mouse down/up events. Internally its implemented as two RepeatButtons and a thumb in the middle. When you click on left or right side of the slider your mouse events are handled by RepeatButtons, and you don't get them.
If you still want to handle handled event you can use AddHandler() method. Here is Silverlight example:
XAML
<Slider Width="100"
VerticalAlignment="Top"
Minimum="0"
Maximum="100"
Name="sl" />
C#
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
sl.AddHandler(MouseLeftButtonDownEvent, new MouseButtonEventHandler(Slider_MouseLeftButtonDown), true);
sl.AddHandler(MouseLeftButtonUpEvent, new MouseButtonEventHandler(Slider_MouseLeftButtonUp), true);
}
private void Slider_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
}
private void Slider_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
}
}
In WPF situation is almost same (small differences in names).
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.
I am trying to synchronize the horizontal scroll position of 2 WPF DataGrid controls.
I am subscribing to the ScrollChanged event of the first DataGrid:
<toolkit:DataGrid x:Name="SourceGrid" ScrollViewer.ScrollChanged="SourceGrid_ScrollChanged">
I have a second DataGrid:
<toolkit:DataGrid x:Name="TargetGrid">
In the event handler I was attempting to use the IScrollInfo.SetHorizontalOffset, but alas, DataGrid doesn't expose IScrollInfo:
private void SourceGrid_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
((IScrollInfo)TargetGrid).SetHorizontalOffset(e.HorizontalOffset);
// cast to IScrollInfo fails
}
Is there another way to accomplish this? Or is there another element on TargetGrid that exposes the necessary IScrollInfo to achieve the synchronization of the scroll positions?
BTW, I am using frozen columns, so I cannot wrap both DataGrid controls with ScrollViewers.
There is great piece of code to do this:
http://www.codeproject.com/KB/WPF/ScrollSynchronization.aspx
According to the Microsoft product group, traversing the visual tree to find the ScrollViewer is the recommended method, as explained in their answer on Codeplex.
We had this same problem when using the Infragistics grid because it didn't (still doesn't) support frozen columns. So we had two grids side-by-side that were made to look as one. The grid on the left didn't scroll horizontally but the grid on the right did. Poor man's frozen columns.
Anyway, we ended up just reaching into the visual tree and pulling out the ScrollViewer ourselves. Afterall, we knew it was there - it just wasn't exposed by the object model. You could use a similar approach if the WPF grid does not expose the ScrollViewer. Or you could subclass the grid and add the functionality you require to make this work.
Interested in hearing why you need to do this.
This is a great solution. Worked fine for me in WPF.
http://www.codeproject.com/Articles/39244/Scroll-Synchronization
I just made a reference to ScrollSynchronizer dll, added a xml import:
xmlns:scroll="clr-namespace:ScrollSynchronizer"
then just added this to both my datagrids and bobs your uncle:
<DataGrid.Resources>
<Style TargetType="ScrollViewer">
<Setter Property="scroll:ScrollSynchronizer.ScrollGroup" Value="Group1" />
</Style>
</DataGrid.Resources>
You can trick the datagrid to expose its ScrollViewer as public property for each grid, when for example innerGridControl_ScrollChanged() handler called during initialisation of the usercontrol.
To expose it you can make your grid in an xaml View file, and then compose two of them in another xaml View.
Below code is on the innerGrid.xaml.cs for example:
public ScrollViewer Scroller { get; set; } // exposed ScrollViewer from the grid
private bool _isFirstTimeLoaded = true;
private void innerGridControl_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
if (_isFirstTimeLoaded) // just to save the code from casting and assignment after 1st time loaded
{
var scroller = (e.OriginalSource) as ScrollViewer;
Scroller = scroller;
_isFirstTimeLoaded = false;
}
}
on OuterGridView.xaml put an attached event handler definition:
<Views:innerGridView Grid.Row="1" Margin="2,0,2,2" DataContext="{Binding someCollection}"
x:Name="grid1Control"
ScrollViewer.ScrollChanged="Grid1Attached_ScrollChanged"
></Views:innerGridView>
<Views:innerGridView Grid.Row="3" Margin="2,0,2,2" DataContext="{Binding someCollection}"
x:Name="grid2Control"
ScrollViewer.ScrollChanged="Grid2Attached_ScrollChanged"
></Views:innerGridView>
then access that public ScrollViewer.SetHorizontalOffset(e.HorizontalOffset) method when another scrolling event occur.
Below code is in the OuterGridView.xaml.cs on one of the handler definition (
private void Grid1Attached_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
if (e != null && !e.Handled)
{
if (e.HorizontalChange != 0.0)
{
grid2Control.Scroller.ScrollToHorizontalOffset(e.HorizontalOffset);
}
e.Handled = true;
}
}
private void Grid2Attached_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
if (e != null && !e.Handled)
{
if (e.HorizontalChange != 0.0)
{
grid1Control.Scroller.ScrollToHorizontalOffset(e.HorizontalOffset);
}
e.Handled = true;
}
}
Also make sure any other scroll_changed event inside the inner grid (if any, for example if you define a TextBox with default scroller in one of the column data template) has its e.Handled set to true to prevent outer grid's handler processing it (this happened due to default bubbling behaviour of routedevents). Alternatively you can put additional if check on e.OriginalSource or e.Source to filter the scroll event you're intended to process.