I've got a xaml TabControl and on one page, there are 3 RadioButtons each bound to a different property on the selected value of an adjacent ListView. After switching between selected items in the ListView, my radio buttons seem to forget they're bound and don't refresh.
So watching it in the debugger, when I switch to a new selected item, I see the non user code first checking the value on all 3 properties, then only the first two, and eventually only the first. However, if I change the tab and change back, it seems to give me another few uses.
The binding itself is fairly straightforward. a TwoWay binding of a bool property to IsChecked. It's 4 levels deep (Path=DataModel.Selected.A.B), but I have other things at the same depth that work fine.
Is this something people have heard about and know what might be going on? Or if the binding is somehow getting forgotten, is there a way to explicitly remind the xaml?
It is possible to manually update bindings like this:
TestCheckBox
.GetBindingExpression(CheckBox.IsCheckedProperty)
.UpdateTarget();
That being said, I don't have 100% confidence that this will correct your underlying issue. I haven't had this sort of issue before with WPF bindings, but I have had a couple weird issues with the tab control.
This is apparently somewhat of a known issue:
http://social.msdn.microsoft.com/forums/en-US/wpf/thread/8eb8280a-19c4-4502-8260-f74633a9e2f2/
In short, a RadioButton (through .Net 3.5sp1) somehow kills bindings of other RadioButtons when when it's checked while trying to uncheck any other buttons. The simple fix (read: hack) is to assign each radiobutton a different GroupName and then they don't try to mess with eachother
Another way to resolve this issue is to fake up a list of properties in a ListBox and have the ListBoxItem template be a radiobutton.
Related
Background:
I use converters to acquire values for most of my binding statement because the bindings are so complicated that even multi-binding cannot satisfy. I have to calculate the value in the converters and return the value. Also I use OneWay or OneTime binding just to show the correct value. When user changes a value, I use Handlers to set the value. The Handlers are also complex program which cannot be simply replaced by TwoWay or OneWayToSource binding. Actually in this case the DataContext does not have any meaning. I use converters. Another reason of using converters is that all Controls are loaded dynamically using many DataTemplates and it's hard to create dynamic DataContext for each Controls in each DataTemplate.
With above background, my application works fine. I'm looking for solutions for our new problem below.
I have many group of Buttons each represent a warehouse containing different type of items.
When double-click a Button, a detail window pops up and user can modify the items. Those items can be represented by CheckBox, Combobox, TextBlocks, TextBox, etc.
For user's convenience, I duplicated some of the frequently-modified Controls from the popup window onto the Button itself (WPF allows Button to contain sub-controls), so that user can directly modify the items without double-click and popup the detail window.
Each Button could contain unknown number of sub-controls such as CheckBox, Combobox, TextBlocks, etc. Here "unknown" means that in the future developer can duplicate any controls onto the Button if the Controls for those items are deemed frequently-modified.
Everything works fine so far.
When user modifies an item in the popup window and closes the window, I used to reload the DataTemplate for the whole window so that everything is refreshed and the controls duplicated onto the Button can synch up with the value modified from inside the popup window.
Everything still works fine so far.
The problem happens when the application runs on machine with slow hardware, where performance is an issue. On a much slower machine, reloading the whole DataTemplate for the whole application that contains many Buttons is quite slow.
So I'm looking for ways to just refresh the Button that is double-clicked, not all Buttons. However, I searched a couple of days and could not find ideal solution of refreshing a WPF sub-tree.
I tried to travel the sub-tree of the Button to assign null to the DataContext property and then assign back the old DataContext, but the binding seems not triggered and the converters were not called.
I saw someone suggested to use something like below:
((ComboBox)sender).GetBindingExpression(ComboBox.ItemsSourceProperty)
.UpdateTarget();
That demands that I know the Control and its property that has bindings. I think I can do the same for all possible Controls and properties but it does not seem a future-proof solution.
Anybody knows an effective way of refreshing a WPF sub-tree without knowing what is in the sub-tree?
i want to immitate the behavior of multiselection of items (eg. in a list view) and their appearence in a PropertyGrid. So, obly the same properties are shown and values set in the grid are set on all multiselected properties.
I have created a listview with some datatemplates and have in another listview some data(with databinding). Now i want wo have a multiselection on the listview with the data and have the properties shown in the another listview like in a propertygrid.(explanation: The ProprtyGrid is still not available in WPF and if has not the flexibility of showing data the way i need it)
So, how do i need to prepare my data to be shown in the list propertygrid-multiselection-style? Is that even possible???
Greets,
Jürgen
I'm not sure if this question is still active, or what not. But I have found a solution that works for me - and I need somewhere to share it.
The first issue you are going to have solve is selecting the items, ie. multi-select. See my tip here that explains how to do that.
Next, I guess its basically binding to listview's selectedItem property and how you want to update your propertyGrid based on changes to the selectedItem prop.
Hope this helps.
I have buttons on my Silverlight page where the opacity is bound to one of two properties on my ViewModel. I'm using the button command that changes the properties, in theory to affect all buttons bound to that property, but the only control that gets affected is the button that initiates the command (any one of them).
Any ideas on why the additional bindings don't work?
The whole thing is actually a little more complex where the buttons are on a Control with the bindings as DependencyProperties mapping back to the VM, and the bound properties are going through a ValueConverter.
It sounds like you need to raise the INotifyPropertyChanged.PropertyChanged event for the properties that are changing. This will let the controls that are bound to them know that there is a change and that they need to come back and get the latest value.
I found the problem. The opacity binding wasn't working, but what was happening was the button was disabling itself based on the predicate I had set in the RelayCommand. It looked like the effect I wanted, but only affected the button being pressed because each button was bound to a seperate ICommand.
I changed it to remove change the binding from the OpacityProperty to the IsEnabledProperty, and removed the predicate from the RelayCommand declaration. It all works now as intended.
I don't know why the button would change to a disabled view when it checks the predicate (and finds it false), but never change back if the condition changes. Odd.
Is there any way to tell when the containers are finished being made for a ListView?
A detailed explanation of what I've done so far
I have a ListView control that has a DataTemplate in one of its columns that contains a CheckBox Control.. I've figured out how to access the CheckBox dynamically using the object that the ListView is bound to.
ListViewItem lItem = (ListViewItem)ListView.ItemContainerGenerator.ContainerFromItem(trackToHandle);
CheckBox checkBoxToHandle = FindChild<CheckBox>(lItem, "CheckBox");
The problem is that the CheckBoxes "reset" (become unchecked) whenever I scroll too far or whenever I sort the columns.
I figured out this was because the VirtualizingStackPanel was only spitting out containers for those ListViewItems that were visible (or almost visible)..
And because the CheckBox is inside a DataTemplate that is defined in the XAML it gets thrown away everytime it goes out of view or when the list is sorted.
I got around this by creating a separate list of CheckBoxes and using the actual CheckBoxes "click" event to change the state of the corresponding CheckBox in my list.. then made a little method to go change the state of all the visible CheckBoxes whenever the user scrolls... as a result it appears like it should have in the first place.
Except when I sort the columns.
I tried making it re-do the CheckBoxes (like before) right after it'd sorted a column but it didn't work.
My best guess is that it doesn't immediately make the containers after I sort..
Is there any way to tell when the containers are finished being made for a ListView?
If you bind your checkboxes IsChecked property to a boolean property on your data context, then you will not have this issue.
The whole purpose of the VirtualizingStackPanel is reduce memory usage by not creating ListItem's unless needed.
In effect, you need to move the data side of the checkbox away from the control.
I'm trying to achive displaying the RowDetailsTemplate of a Silverlight DataGrid depending on a bool Property, bound to a CheckBox Control's IsChecked Property. Insinde of my RowDetailsTemplate there is a single custom UserControl, containing further Controls.
Since the DataGrid only allows a global setting (RowDetailsVisibilityMode) Some code-behind is needed. I've implemented a solution based on Rorys Reply (and using a behaviour-technique) which actually works.
Unfortunately, The DataGrid doesn't remember the individually shown or hidden Rows on sorting. The checkbox remains selected, but the Row collapses. Further, no event like "OnAfterSort" or something similar seems to exist, where i could "Refresh" the visibility settings in a loop.
Another idea was to bind the Visibility of my custom Details-UserControl to the CheckBox bound value. This actually works (when settings RowDetailsVisibilityMode to "Visible"), but I'm not able to get rid of this weird behaviour: When the CheckBox is checked, the Detail Template expands and the detail UserControl appears. Nice. When the CheckBox is unchecked again, the UserControl disappears (Visibility is set to Collapsed) but the Row doesn't collapse and the blank space remains (as it would be set to Hidden not Collapsed).
Do you have any ideas?
I hope it's ok I didn't post any code samples, the implementation is pretty easy and I believe that the problem doesn't actually lie in a coding mistake i made. You can setup a simple DataGrid quickly like in this perfect MSDN Example. Starting from here, it's easy to test both described behaviours!
Really big thanks in advance,
- Thomas