I have a textbox and several custom controls. Each of the custom controls has a "hint text" property that should appear in the textbox when that control is hovered over.
In winforms I was able to just give the custom control a textbox property and change its text property with events, however in WPF it instead makes a new textbox when I give it a property.
So how can I get the desired functionality?
Assuming your custom controls all inherit from a common base type (which I have called CustomControl as an example)...
XAML:
<TextBox x:Name=TextBox/>
<Button VerticalAlignment="Bottom" Click="ButtonBase_OnClick" MouseEnter="UIElement_OnMouseEnter" MouseLeave="UIElement_OnMouseLeave">test</Button>
Code behind:
private void UIElement_OnMouseEnter(object sender, MouseEventArgs e)
{
TextBox.Text = ((CustomControl) sender).HintText;
}
private void UIElement_OnMouseLeave(object sender, MouseEventArgs e)
{
TextBox.Text = string.Empty;
}
Related
Does anyone know how to dynamically set the ElementName for textblock.text binding?
I have two Datagrids that have the same information but the second DataGrid is just a filter of the same datasource, but what I want is to bind text of a textblock to the selected item depending if the item was clicked in the main datagrid or the secondary datagrid.
I have the below code to bind the textblock to one datagrid but I would also like the same to happen if the user clicked an item in the secondDataGrid.
Is this possible?
<TextBlock Margin="29,0" Text="{Binding SelectedItem.Name, ElementName=MainDataGrid}"
It is possible, though I don't think this is the proper solution.
You can handle one of the DataGrids' events in the code-behind, where in the handler you can write the following code:
BindingOperations.SetBinding(textBlock, TextBlock.TextProperty,
new Binding("SelectedItem.Name")
{
ElementName = "DataGrid1"
});
Basically you reset the Binding on the TextBlock's Text property with this code, where:
textBlock is the name of your TextBlock;
with TextBlock.TextProperty you define that you want to work with the Text property on the TextBlock;
The third paramter is the new Binding itself. The constructor takes the Path of the Binding and then in the "body" I set the ElementName.
If DataGrid1 fires the event you set the ElementName to that DataGrid's name, if DataGrid2 fires the event then you set the ElementName to the second DataGrid's name.
SelectionChanged can be a good event to handle on both DataGrid, but if you want the TextBlock to update when you selected and element in the first then select another one in the second and then click back to the first element to update then you need to handle the GotFocus event as well.
Play a little bit with it and you will see what I mean.
My working example:
private void SetBindingOnTextBlock(string elementName)
{
BindingOperations.SetBinding(textBlock, TextBlock.TextProperty, new Binding("SelectedItem.Name")
{
ElementName = elementName
});
}
private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
SetBindingOnTextBlock("DataGrid1");
}
private void DataGrid_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
{
SetBindingOnTextBlock("DataGrid2");
}
private void DataGrid1_GotFocus(object sender, RoutedEventArgs e)
{
SetBindingOnTextBlock("DataGrid1");
}
private void DataGrid2_GotFocus(object sender, RoutedEventArgs e)
{
SetBindingOnTextBlock("DataGrid2");
}
UPDATE 1:
Set
IsSynchronizedWithCurrentItem="True"
on the DataGrids and it may solve your problem if ItemsSources are the same. (Not sure if this is what #dkozl meant) Originally I assumed that they are different.
I am trying to bind the IsEnabled property of a button to properties of the window's CollectionViewSource. I am doing this to implement First/Previous/Next/Last buttons and want the First and Previous to be disabled when the view is on the first item etc.
I have the collection view source set up, UI controls binding to it correctly, with access to its view in code so the click event handlers work fine in navigating through the view.
<CollectionViewSource x:Key="cvMain" />
The DockPanel is the root element of the window
<DockPanel DataContext="{StaticResource cvMain}">
FoJobs is an observable collection, cvJobs is a CollectionView that I use in the button's click handler
private void Window_Loaded(object sender, RoutedEventArgs e) {
((CollectionViewSource)Resources["cvMain"]).Source = FoJobs;
cvJobs = (CollectionView)((CollectionViewSource)Resources["cvMain"]).View;
}
I have tried this but get a binding error "BindingExpression path error: '' property not found on 'object' ''ListCollectionView'"
<Button Name="cbFirst" Click="cbMove_Click" IsEnabled="{Binding Source={StaticResource cvMain}, Converter={StaticResource CurrPos2BoolConverter}}" />
I am trying to do with a converter first but figure a style with triggers would be more efficient, but cant get access to the collection view. Even though the underlying datacontext is set to a collection view source, the binding is passed to the converter as the view's source (if I dont explicity set the binding's Source, as above), which has no currency properties (CurrentPosition, Count etc).
Any help would be greatly appreciated.
Why don't you use a RoutedCommand for this(even if you don't use MVVM that is)?
say something like:
<Button x:Name="nextButton"
Command="{x:Static local:MainWindow.nextButtonCommand}"
Content="Next Button" />
and in your code-behind:
public static RoutedCommand nextButtonCommand = new RoutedCommand();
public MainWindow() {
InitializeComponent();
CommandBinding customCommandBinding = new CommandBinding(
nextButtonCommand, ExecuteNextButton, CanExecuteNextButton);
nextButton.CommandBindings.Add(customCommandBinding); // You can attach it to a top level element if you wish say the window itself
}
private void CanExecuteNextButton(object sender, CanExecuteRoutedEventArgs e) {
e.CanExecute = /* Set to true or false based on if you want button enabled or not */
}
private void ExecuteNextButton(object sender, ExecutedRoutedEventArgs e) {
/* Move code from your next button click handler in here */
}
You can also apply one of the suggestions from Explicitly raise CanExecuteChanged() to manually re-evaluate Button.isEnabled state.
This way your encapsulating logic relating to the button in one area.
I have a WPF TreeView with a HierarchicalDataTemplate.
Currently I have to double click an item to expand/collapse it.
I would like to change this behaviour to a single click, without loosing other functionality. So it should expand and collapse on click.
What is the recommended way to do this?
Thanks!
You could use a re-templated checkbox as your node (containing whatever template you are currently using) with its IsChecked property bound to the IsExpanded property of the TreeViewItem.
Here is a template I've just test that seems to do the job:
<HierarchicalDataTemplate ItemsSource="{Binding Items}">
<CheckBox IsChecked="{Binding RelativeSource={RelativeSource AncestorType=TreeViewItem}, Path=IsExpanded}">
<CheckBox.Template>
<ControlTemplate>
<TextBlock Text="{Binding Header}"></TextBlock>
</ControlTemplate>
</CheckBox.Template>
</CheckBox>
</HierarchicalDataTemplate>
Just replace the ControlTemplate contents with whatever you need.
If you are using a standard TreeViewItem, then you can capture the click event:
private void OnTreeViewMouseUp( object sender, MouseButtonEventArgs e )
{
var tv = sender as TreeView;
var item = tv.SelectedItem as TreeViewItem;
if( item != null )
item.IsExpanded = !item.IsExpanded;
e.Handled = true;
}
private void OnTreeViewPreviewMouseDoubleClick( object sender, MouseButtonEventArgs e )
{
e.Handled = true;
}
Most likely in your case, you'll need to do something with your binding and ViewModel. Here's a good article from CodePlex: Simplifying the WPF TreeView by Using the ViewModel Pattern.
Just use selected item changed event and use the following,
private void treeview_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
TreeViewItem item = (TreeViewItem)treeview.SelectedItem;
item.IsExpanded = true;
}
where treeview is the name of your TreeView, you could include an if to close/open based on its current state.
I have very little experience working with WPF to this point, so I am not 100% certain here. However, you might check out the .HitTest method of both the Treeview and TreeView Item (the WPF Treeview is essentially the Windows.Controls.Treeview, yes? Or a derivation thereof?).
THe HIt Test method does not always automatically appear in the Intellisense menu for a standard Windows.Forms.Treeview (I am using VS 2008) until you type most of the method name. But it should be there. You may have to experimnt.
You can use the .HitTest Method to handle the MouseDown event and return a reference to the selected treeview item. You must test for a null return, however, in case the use clicks in an area of the control which contains no Tree Items. Once you have a reference to a specific item, you should be able to set its .expanded property to the inverse of whatever it is currently. again, some experimentation may be necessary here.
As I said, I have not actually used WPF yet, so I could have this Wrong . . .
The answer of Metro Smurf (thanks to which I got where I wanted to be) suggests the right approach . You could simply hook up to the SelectedItemChanged event of the Treeview. Then cast the e.NewValue passed in the eventhandler as TreeViewItem, and access its IsExpanded property to set it to true.
void MyFavoritesTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
((TreeViewItem)e.NewValue).IsExpanded = true;
}
Then for the final touch, you can also hook up the items in your Treeview by casting them as TreeViewItem as suggested, and then you can hook up to the various manipulation events, like:
var item = tv.SelectedItem as TreeViewItem;
item.Expanded += item_Expanded;
And then do whatever you need to do in the eventhandler
void item_Expanded(object sender, RoutedEventArgs e)
{
// handle your stuff
}
Despite some posts on this forum and others i cannot find something that tells me how to set the focus on a TextBox.
I have a userControl with many labels and textBoxes. When the form is loaded I want the a particular textBox to have the focus.
I have set the tabIndex but that didn't seem to work.
Any suggestions?
You can use the FocusManager.FocusedElement attached property for this purpose. Here's a piece of code that set the focus to TxtB by default.
<StackPanel Orientation="Vertical" FocusManager.FocusedElement="{Binding ElementName=TxtB}">
<TextBox x:Name="TxtA" Text="A" />
<TextBox x:Name="TxtB" Text="B" />
</StackPanel>
You can also use TxtB.Focus() in your code-behind if you don't want to do this in XAML.
You can apply this property directly on the TextBox :
<TextBox Text="{Binding MyText}" FocusManager.FocusedElement="{Binding RelativeSource={RelativeSource Self}}"/>
I am new to using WPF and reading through the above examples I had a similar experience trying set the focus to a textbox using the xaml code examples given, i.e. all the examples above didn't work.
What I found was I had to place the FocusManager.FocusElement in the page element. I assume this would probably work as well if you used a Window as the parent element. Anyway, here is the code that worked for me.
<Page x:Class="NameOfYourClass"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
Title="Title"
Height="720"
Width="915"
Background="white"
Loaded="pgLoaded"
FocusManager.FocusedElement="{Binding ElementName=NameOfYourTextBox}">
<!-- Create child elements here. -->
</Page>
I have a TextBox inside a Grid inside a DataTemplate which I want to have keyboard focus when it becomes visible. I also found that
<DataTemplate x:Key="DistanceView" DataType="{x:Type vm:ROI}">
<Grid FocusManager.FocusedElement="{Binding ElementName=tbDistance}">
<TextBox x:Name="tbDistance" Grid.Column="1" Grid.Row="1" VerticalAlignment="Bottom"/>
</Grid>
</DataTemplate>
did not work for me.
However when I call Focus() in the parent ContentControl
private void ContentControl_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
if ((sender as ContentControl).IsVisible)
{
(sender as ContentControl).Focus();
}
}
it starts to work and the caret is visible in the TextBox. I think the FocusScope has to be given focus for the FocusManager.FocusedElement property to have any effect.
Jerry
From experimenting around, the xaml solution
FocusManager.FocusedElement="{Binding ElementName=yourElement}"
seems to work best when you place it in the highest element in the window hierarchy (usually Window, or the Grid you place everything else in)
Usage:
local:FocusManager.FocusOnLoad="True"
public class FocusManager
{
public static readonly DependencyProperty FocusOnLoad = DependencyProperty.RegisterAttached(
"FocusOnLoad",
typeof(bool),
typeof(FocusManager),
new UIPropertyMetadata(false, new PropertyChangedCallback(OnValueChanged))
);
private static void OnValueChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
if (!(sender is Control control))
return;
if ((bool) e.NewValue == false)
return;
control.Loaded += (s, e) => control.Focus();
}
public static bool GetFocusOnLoad(DependencyObject d) => (bool) d.GetValue(FocusOnLoad);
public static void SetFocusOnLoad(DependencyObject d, bool value) => d.SetValue(FocusOnLoad, value);
}
FocusManager was not in intellisense and this confused me a bit. I just typed the entire attribute and it worked.
FocusManager.FocusedElement="{Binding ElementName=MyTextBox}"
Microsoft Visual Studio Enterprise 2015 version 14.0.23107.0/C#/WPF
For completeness, there is also a way to handle this from code behind (e.g. in the case of controls that, for whatever reason, are created dynamically and don't exist in XAML). Attach a handler to the window's Loaded event and then use the ".Focus()" method of the control you want. Bare-bones example below.
public class MyWindow
{
private VisualCollection controls;
private TextBox textBox;
// constructor
public MyWindow()
{
controls = new VisualCollection(this);
textBox = new TextBox();
controls.Add(textBox);
Loaded += window_Loaded;
}
private void window_Loaded(object sender, RoutedEventArgs e)
{
textBox.Focus();
}
}
bind the element you want to point the focus in as
FocusManager.FocusedElement= "{Binding ElementName= Comobox1}"
in grid or groupbox etc
Further to my comment on Feb 04 '22, I solved it this way:
In the UserControl definitionin the XAML add a Loaded event handler. (pressing tab after Loaded= will automatically add an event handler to the code behind)
Then edit the event handler in the code behind:
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
expressionTextBox.Focus();
}
I'm hoping that WPF is clever enough to handle th unhooking of the evnt at some point, allowing the class to be garbage collected and not give rise to memory leaks, but I don't know. I'd be interested in any comments on that.
Is there any way for me to do this?
You can tell when the VerticalOffset changes by adding a handler to the ScrollViewer.ScrollChanged event to your TextBox. Something like this:
<TextBox AcceptsReturn="True" ScrollViewer.ScrollChanged="TextBox_ScrollChanged" />
The TextBox uses a ScrollViewer internally, so it's ScrollChanged event will bubble up to the TextBox (where you can handle it). The event arguments include information about what changed, such as the VerticalChange (the amount that the control has scrolled vertically).
private void TextBox_ScrollChanged(object sender, ScrollChangedEventArgs e) {
System.Diagnostics.Debug.WriteLine(string.Format("************ {0}", e.VerticalChange));
}