I have used a custom control in wpf from Source code for multiselect. that control is a multiselect combobox with checkbox. but selection changed event is not present in that.I am trying to create a selection changed event using DependencyProperty. I am new to WPF. I don't know how to use DependencyProperty for creating events. Can Anyone tell me how to create selection change event in that control.
Combobox image is here
You need to use a RoutedEvent.
Create a custom routed event
But better yet you can use an existing routed event from the selector class called SelectionChanged
Raising the selection changed event from your code: psedo code since i am not near vs.
SelectionChangedEventArgs args = new SelectionChangedEventArgs();
args.AddedItem.add(... how ever is checked ..);
args.RemovedItem.add(... how ever was unchecked ..);
this.RaiseEvent(args); // this your control.
Related
I linked a combobox SelectedValue to a class. I noticed, the class value is changed only when I exit the control.
How do I change this behavior and set the class value when the combobox SelectedValue is changed and has focus yet?
Is it possible that your code is currently listening for the SelectionChangeCommitted event? If so, give SelectedIndexChanged a try.
The SelectionChangeCommitted event is raised only when the user changes the combo box selection, and you can create a handler for this event to provide special handling for the ComboBox when the user changes the selected item in the list. However, depending on how the ComboBox is configured, and how the user changes the selected item, the SelectionChangeCommitted event may not be raised. Alternatively, you can handle the SelectedIndexChanged, but note that this event occurs whether the index is changed programmatically or by the user.
Hello I am working on a simple MVVM project; a simple text/config editor that loads a config file and then it checks in the ViewModel in case the file has been changed, it enables the Save menu item simply by binding a boolean property. But here comes a problem, where I can't find any property in the textbox control that could be bound to a vm property in case a change happens in the text. I have managed to somehow simulate this by creating an event in the code-behind :
(DataContext as AnalizeSectionViewModel).ContentChanged = true;
The event is fired on any text change. But I would like to bind a property from the textbox, something like:
IsModified="{Binding ContentChanged}"
Can such a thing be done?
You should be able to just bind the Text textbox property to your model via binding
Text="{Binding MyViewModelProperty}"
Anytime the text in your textbox changes your property in your model will change which will allow you to do 'stuff' when that occurs. This will fire the property changed event when the user moves to out of the field.
Now, if the intent is for it to fire each time the user types then you can explicitly tack on the
UpdateSourceTrigger="PropertyChanged"
By setting it to PropertyChanged, you will get a notification each and every time the text changes.
I have a long form with a bunch of CheckBox's and occasionally some TextBox inputs. I want an event to be raised any time any control is changed (i.e., any CheckBox state is changed or any TextBox.Text is altered). Is there a global way to do this without having to add an event handler to each and every control?
One of the advantages of WPF and its declarative nature is that events are inherited down the visual tree.
<Window x:Class="MyApplication.MainWindow"
....
TextBox.TextChanged="TextBox_TextChanged" CheckBox.Checked="CheckBox_Checked">
All TextBox and CheckBox controls will inherit these event handlers. The same approach can be taken in other controls such as Grid so only the controls within the Grid are affected.
One way do this would be to subclass the CheckBox and TextBox classes and implement the required handlers in those classes.
You will still need to go through your application and replace the standard CheckBox and TextBox with your classes.
You can use TextBoxBase.TextChanged="MainWindow_OnTextChanged" on window or user control.
There are so called class events in WPF. Put this in the form's constructor:
EventManager.RegisterClassHandler(typeof(TextBox), TextBox.TextChangedEvent,
new RoutedEventHandler(AnyTextBox_OnTextChanged));
This way you register a handler to TextChanged event of all text boxes. Similarly with check boxes:
EventManager.RegisterClassHandler(typeof(CheckBox), CheckBox.CheckedEvent,
new RoutedEventHandler(AnyCheckBox_OnChecked));
I want to set up an event to run when the Visibility is changed on a WPF Canvas control.
canvas1.VisibleChanged += new EventHandler(canvas1_VisibleChanged);
I have tried the above but it doesn't work, anyone know how to do it ?
You're looking for the IsVisibleChanged event, which applies to ALL UIElements:
UIElement.IsVisibleChanged
More Information: IsVisible is a read-only Dependency Property. It is a calculated value, and the Visibility Dependency Property affects it. This is what you should use to detect if you're UIElement is visible or not.
Now, if you really really wanna just check for the Visibility DP changing for whatever reason there is a way to do so: http://agsmith.wordpress.com/2008/04/07/propertydescriptor-addvaluechanged-alternative/
Though, I'd still stick with just tracking the IsVisibleChanged.
The normal WPF Canvas object does not have a .VisibleChanged event, so you can't assign an event handler to it.
I'm using the Control.TextChanged event to detect when the user has modified the form. I have a method that loops through every control and adds the same TextChanged to all the controls.
My problem is, on the form I also have databinding that binds bindings that have Binding.Format() and Binding.Parse(), and these are within a TabControl. If the user changes tabs (SelectedIndexChanged), it then activates the Format/Parse and fires the TextChanged event which makes it seem like the form's been modified!
How can I either (1) keep the bindings or Binding.Format and .Parse from firing the TextChanged event, or (2) implement a better way to detect of the controls on the form have been modified?
Instead of checking the actual TextChanged Event, check the backing properties and look at when they change. You can make use of INotifyPropertyChanged to help out with this.