I got a pretty complex WPF-Window with a lot of sub controls using strict MVVM. One of them is an ItemsControl. What I want to accomplish is to propagate a PropertyChanged-Event to Items within the ItemsControl when the Alt-Key is pressed anywhere - not just when the ItemsControl is focused. How can I do that?
An example: when I press the LeftAlt-Key anywhere within the Main Window I want to change the text of a button which is part of an item within an ItemsControl.
see similar question here
answer with more than 100 upvotes
or consider using a Behavior with command
Edit :
Behavior on the upper control(MainView i guess) to register to the KeyDown Event and excute a command on your ViewModel
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When using a WPF application on windows 10 with a touchscreen we encounter an issue with the listview. When working with a mouse it works fine.
We have created a simple test-project, which is used to simulate the problem on windows 10 and can be found on GitHub. A ticket is also created on MSDN
In short below a summary of the technical setup:
We use a grouped listview, and for each group, a togglebutton and
another (inner) listview.
The inner listview uses an ItemTemplateSelector binded to an
Datatemplate selector, to choose an datatemplate.
There are 3 datatemplates (checkbox, numeric, text) that will be
choosen based upon the type property of the bounded model.
Each datatemplate has a stackpanel. The stackpanel in the text en
numeric datatemplate is wired to an PreviewMouseDown event.
Important, the stackpanel in the checkbox isn't wired to an event.
This works in general well, however sometimes, when touching the checkbox, the
PreviousMouseDown of another template is triggered.
I would expect that this behavior may not happen, is that correct?
We found a workaround (*) for this issue but we didn't find the root
cause.
Why is the event of another template triggered?
I'm starting to believe that this could be an issue with WPF Listview
and touch behavior?
(*) If we know that sometimes an event is triggered from a wrong template,
we verify every event whether that event is originated from the right template and if not we do nothing.
Below you can see when tapping quickly on the checkbox the clickevent get's triggered.
Below more details of the code:
The datatemplates and the selector
The grouped listview with the inner listview and the itemtemplate selector
Below the code behind and the handler for the PreviewMouseDown event
Below an overview of the steps we have been taken in order to resolve
it, but none lead into a solution.
Since WPF is supporting touch and a touch on a screen is also "translated" into a mousedown event, I don't see a problem why not using a previewMouseDown event on a touch screen. I also didn't find any offical documentation of Microsoft in not doing this.
Anyway, I could no longer reproduce the problem that a touch on listviewitem is invoking another previeuwMouseDown event of a template of another listviewitem in the list by ....
Changing the PrevieuwMouseDown event by a Touchdown event!
I am glad to find a solution, however based upon many online searches, I feel there are many issues with thouch on WPF and often it's is not clear what the rootcause is. Like in this case I found a solution by trial and error, but why the problem occurs when using previewMouseDown, is puzzling.
I need to set focus to UserControl itself, not its child.
Otherwise I cannot implement insertion from the buffer. :(
Setting Focusable=True doesn't help.
Google and SO tells only how to set focus to UserControl child.
My control contains:
- Toolbar with several buttons bound to commands of the corresponding
VM
- TextBox which is the input for the filter
- DataGrid - list of items.
I need to bind Ctrl+V command to VM. But to handle this gesture UserControl must have focus within. When there are no items in the grid (VM's collection is empty) buttons are disabled and the only element which can get focus is TextBox. But it handles Ctrl+V in its own way and I don't want to change this behavior.
Thus, I need something to set focus to when I click the area of UserControl.
I believe UserControl is the best candidate for it.
But I don't know how to make it selectable.
The whole problem was in my misunderstanding of controls' behavior.
This SO question clearly shows it I believe.
Thus, setting UserControl.Focusable = true is not sufficient. To make it navigatable via keyboard IsTabStop must be true also. And to make UC selectable by mouse click we should call Focus() in mouse eventhandler. That's it.
I have a textbox and some labels inside the data template of bounded listbox.
When I click on any label the whole item is highlighted in blue, but when I click directly on a different textbox the selection does not change.
Is there a way to make the selection of the listbox change even when a textbox is clicked?
thanks
This is what I've exactly asked few days ago, see post: "WPF: Trigger SelectedIndex changed whilst clicking on any control within a ListBoxItem area"
basically there are few solutions, using code behind and XAML, but I've not verified latter approach yet
The reason is because the TextBox handles the click event in order to receive focus. There are a number of ways to handle this, including but not limited to:
stop the TextBox handling mouse events (which prevents the user from focussing it using the mouse)
use an eventhandler when the TextBox gains focus (or PreviewClick or similar), to select the parent ListItem
Now I'm about to learn RoutedEvents. I understand bubbling and tunneling and all. But I have a little problem I'm not sure how to handle.
I've got a ItemsControl in my own defined UserControl ( inherits TabItem ). This itemsControl could be a ListBox or some selector not decided yet ( depends what is best with this solution ).
Now when one item there is selected ( Not sure yet what the best selection method would be, perhaps doubleclick ) I need to capture the event in the TabControl that holds my UserControl. Thankfully as my userControl is put into the XAML visualtree the bubbling event flows up and events can reach the TabControl. However I still have a few problems with implementing this.
1) Let's say I set it as MouseDoubleClick I don't wan't other DoubleClicks ( like in other tabs or outside the ItemsControlItems ). I guess you can always do a check where the events coming from to ensure it's the right one but I don't feel it's the right way and it could be asking for trouble.
2) If I set the event to SelectionChanged and the ItemsControl to ListBox I would have to ensure the ListBox itself doesn't handle it so it can reach the tabControl. How would I do that?
3) Same as 2) but the TabControl is a selector itself so it would raise it's own selectionchange events wouldn't it. how would that work. Would the handler grab both from the listbox and the TabControl?
4) Not sure what ItemsControl I should use. If i'm only using it to doubleclick the item and then handle the event wouldn't ListBox be too much. It has many effects that would be undisireable like selection and such. Is it better to define your own ItemsControl or maybe use ListBox and overwrite some of it's properties like selection ( how would one do that? )?
5) The source of the event would be the ItemsContainer but I wan't the item itself. There is a easy way to get access to it isn't there?
6) Let's say I put a button and in the DataTemplate I wan't to attach the ID of the object through the button and capture it where the button click is handled to identify what item it was. Is there a property do do that or would I have to define it myself?
7) Would the best course of action here maybe to create my own event?
Your take on this issue and comments on what process is best to take here is appriciated.
EDIT: Decided to add little bit more info as asked.
What I'm aiming for; when I start the program I have a TabControl with 1 tab in it. This tab is different from the rest of the tabs will be because it holds a list of objects (CompanyModel). This list is the ItemsControl I mention. When you press one company from this list a new tab is added with info about that company.
My solution was to create a TabItem collection as a source for the TabControl. Then I would define my 2 types of TabItems in a seperate XAML source file (not sure what to call it, basicly add new usercontrol). One is the initial where thhe list appears, the other one takes in a CompanyModel as a constructor parameter and shows info about that.
This works while I don't like the idea of defining the company list tabitem seperatly I can't define it under the tabcontrol because I can only have defined items or sourced, not both.
I've tried this idea by putting a button on the List DataTemplate that bubbles the Id of the company selected up to the TabControl, handling it there and adding a new TabItem with the CompanyModel. That was just a solution to try it and has problems like if I add anpther button to the CompanyTabs I would grab them aswell in the TabControl.
So my problem could be solved by finding a good way to bubble a event from the original listTab or If I would be able to define the tab in the same place as the TabControl.
I know that one other solution would to have the list seperate from the TabControl but others would like to see how this comes out and I would like to learn how I would do this.
please have a look in this blog, may be it will helps u.
http://blogs.u2u.be/diederik/post/2009/09/09/In-WPF-SelectionChanged-does-not-mean-that-the-selection-changed.aspx
I am using ListBox for having RadioButtonList behaviour (that's what people recommend as there is no inherent radio button list in WPF). The listbox is bound to a ViewModel.
Now, whenever user changes the selection on listbox, I want to check whether user has some unsaved data on the part of screen and prompt accordingly (typical yes,no,cancel). If I use SelectionChanged event, the selection has already occured and hence, prompting is of no use. And there doesn't seem to be any SelectionChanging event.
I am am not sure but can I mimic SelectionChanging behaviour by using WPF binding validation rules?
Or should I use MouseButtonDown event? Would that lead to problems?
You don't need to put them in a listbox, the are group-able like so:
<RadioButton GroupName=“One“ IsChecked=“True“/>
Notice the GroupName, this holds the collection together, as for the rest of your question I am having a slight issue understanding what you need, sorry :(