I'm looking to create a UI element in a WPF XAML UserControl with something that looks and works roughly like Google Suggest - a TextBox with a ListBox that appears beneath it showing suggestions that match the text entered in the TextBox. In simplified form, my XAML looks like this:
<StackPanel>
[...controls above...]
<TextBox ... />
<ListBox ItemsSource="{Binding SearchHints}"
Visibility="{Binding HasSearchHints}" MaxHeight="100" />
[...controls below...]
</StackPanel>
What I'm struggling to achieve is I want the ListBox to float above any content that may come below it, much like the dropdown part of a ComboBox does. Currently it pushes any controls below it downwards. I figure this must be possible because the ComboBox control essentially does exactly what I want to do. In CSS it would be a matter of setting the element to position:relative but there doesn't seem to be an immediately obvious equivalent in XAML. Any ideas?
Used Icepickle's comment - the element did exactly what I wanted.
Related
I have a very strange situation. I have ComboBox which is loaded with some items. When I click on it, the drop-down expands showing all items.
If I now open another application such as Notepad, the dropdown will not collapse which I would expect to happen. As a result, any overlapping application, such as opened Notepad, will appear as being located in between the WPF hosting the ComboBox and the ComboBox drop-down like on screenshot below. Probably the z-order is somehow totally wrong.
I believe the reason for this behavior is the fact that the dropdown did not collapse at the first place. My ComboBox is part of a Usercontrol and its xaml is like:
<ComboBox ItemsSource="{Binding ValueSet}"
SelectedItem="{Binding SelectedNode}"
DisplayMemberPath="Name"
BorderBrush="Green"
BorderThickness="1" SelectionChanged="ComboBox_SelectionChanged">
</ComboBox>
In my opinion there is no any problem with the z-order in your xaml. The actual problem is in the ComboBox template in your application. You should find the actual style(or control template) your Combo is based on and check the Popup(usually named "PART_Popup") control inside that control template. The IsOpen property of the Popup should be bound to the ComboBox IsDropDownOpened property, like that:
`IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}"`
Any way you should search the solution for your problem in incorrect control template of the Combo control. There is something that make it be opened(probably by making the IsOpen property of the inner Popup control to be always true). Let me know if it you need more suggestion.
Is it possible to store some data in every item of a TreeView control? I mean, something useful (e.g. a string) besides the header text?
Thanks.
Yes, WPF is "lookless", so your actual data can be anything you want it to be, and a TreeView is just a Template used to display the data to the user in a pre-determined way.
You can overwrite any part of that Template to be whatever you want, and/or have it bind to your data however you want.
Edit
I'm no expert on using the TreeView, but if you had a DataContext of List<Folder>, and each Folder object had a Name and a FullPath property, your TreeView could look something like this:
<TreeView ItemsSource="{Binding MyFolderList}">
<TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"
ToolTip="{Binding FullPath}" />
</DataTemplate>
</TreeView.ItemTemplate>
</TreeView>
If you haven't already, I'd highly recommend looking into the MVVM design pattern when working with WPF. Basically your application is your classes (ViewModels), and the Controls/XAML (Views) are just a pretty layer that sits on top of your classes to make them user-friendly.
This is an important concept when switching from a WinForms TreeView to a WPF TreeView
It depends on what you mean by store data...
If you're just talking UI customization Rachel's answer above works.
If you're talking about storing arbitrary object values, such as information about the TreeViewItem, or maybe a relation between two items, you can use the Tag property of TreeViewItem. For example, I had to write a mapping UI where two trees linked together where each TreeViewItem from the first tree, could connect to 1 TreeViewItems of the second tree. I used the Tag property of the first TreeViewItem to store the connecting TreeViewItem.
first of all I would like to thank you for the many good posts that i read in this forum. Unluckily I could not find anything of help for my current problem (either here or anywhere else).
What I'm trying to do sounds quite simple, but I have no clue how to get it to work ... perhaps I'm still to new to wpf or I don't thing wpfy enough :)
I'm designing a front end for a part in an automated manufacturing:
I have a quantity of places where pallets can be put (but it can be empty as well).
Each pallet has up to 3 places where parts can be mounted
Everything is created dynamically of a database and is reacting to changes.
The position of the parts on the pallet comes from the database as well and should be visualized
What I would like to have is:
An overview over the pallet-places with a preview of the pallet
When I select a place I want to see a detail view of the place
When I click on a part on the pallet of the detailed pallet I want to see details to the part
The first two points are quite simple and work nicely:
I have got a DataTemplate for every component (part, pallet, pallet-place). Actually those are UserControls that are imported as Datatemplates
the overview is a ListBox with the places as DataContext
for the detail-place-view I use the UserControl and bound it to the SelectedItem of the Listbox
I tried to bind the Text of a Textblock to the ID of the selected Part ... and fail.
Probably I could use some global variables in the code behind - but that sound very ugly.
Can anybody help?
I have got a solution ... it is not nice but works.
I created an event in the pallet, that triggers, when the selected part-place changes
I handle the event in the pallet-place and create a new one
And finally I handle it in the overview and change the detailview accordingly
Most likely there are much nicer solutions, but it will suffice.
Perhaps try an ElementName binding?
<TextBlock Text="{Binding ElementName=Name_of_your_Listbox, Path=SelectedItem.ID" />
Can you post a bit more code of your TextBlock and your Binding?
Context is important, if i use a ContentControl and bind its content to the SelectedItem like this:
<ContentControl Content="{Binding SelectedItem, ElementName=mylistbox}">
I can bind to the ID of the selected item in the DataTemplate like this:
<ContentControl.ContentTemplate>
<DataTemplate>
<TextBlock Text="{Binding ID}" />
</DataTemplate>
</ContentControl.ContentTemplate>
That is because setting the Content of the ContentControl automatically sets the DataContext as well, and this binding is relative to the DataContext since no source (ElementName, RelativeSource, Source) has been specified.
I do not know how your UserControl handles the context, if the DataContext is not affected such bindings will not work. You would need to bind directly then:
<uc:MyDetailsView Data="{Binding SelectedItem, ElementName=mylistbox}">
<!-- ... -->
<TextBlock Text="{Binding SelectedItem.ID, ElementName=mylistbox}" />
This of course defeats the purpose of having the binding on the UserControl itself in the first place. But unless you post some relevant code it's quite hard to tell what is wrong.
Also check the Output window in VisualStudio, binding errors will show up there and might provide valuable information as to what went wrong.
In the above image, child is a ContentPresenter. Its Content is a ViewModel. However, its ContentTemplate is null.
In my XAML, I have a TabControl with the following structure:
<local:SuperTabControlEx DataContext="{Binding WorkSpaceListViewModel}"
x:Name="superTabControl1" CloseButtonVisibility="Visible" TabStyle="OneNote2007" ClipToBounds="False" ContentInnerBorderBrush="Red" FontSize="24" >
<local:SuperTabControlEx.ItemsSource>
<Binding Path="WorkSpaceViewModels" />
</local:SuperTabControlEx.ItemsSource>
<TabControl.Template>
<ControlTemplate
TargetType="TabControl">
<DockPanel>
<TabPanel
DockPanel.Dock="Top"
IsItemsHost="True" />
<Grid
DockPanel.Dock="Bottom"
x:Name="PART_ItemsHolder" />
</DockPanel>
<!-- no content presenter -->
</ControlTemplate>
</TabControl.Template>
<TabControl.Resources>
<DataTemplate DataType="{x:Type vm:WorkSpaceViewModel}">
....
WorkSpaceViewModels is an ObservableCollection of WorkSpaceViewModel. This code uses the code and technique from Keeping the WPF Tab Control from destroying its children.
The correct DataTemplate - shown above in the TabControl.Resource - appears to be rendering my ViewModel for two Tabs.
However, my basic question is, how is my view getting hooked up to my WorkSpaceViewModel, yet, the ContentTemplate on the ContentPresenter is null? My requirement is to access a visual component from the ViewModel because a setting for the view is becoming unbound from its property in the ViewModel upon certain user actions, and I need to rebind it.
The DataTemplate is "implicitly" defined. The ContentPresenter will first use it's ContentTemplate/Selector, if any is defined. If not, then it will search for a DataTemplate resource without an explicit x:Key and whose DataType matches the type of it's Content.
This is discussed here and here.
The View Model shouldn't really know about it's associated View. It sounds like there is something wrong with your Bindings, as in general you should not have to "rebind" them. Either way, an attached behavior would be a good way to accomplish that.
I think the full answer to this question entails DrWPF's full series ItemsControl: A to Z. However, I believe the gist lies in where the visual elements get stored when a DataTemplate is "inflated" to display the data item it has been linked to by the framework.
In the section Introduction to Control Templates of "ItemsControl: 'L' is for Lookless", DrWPF explains that "We’ve already learned that a DataTemplate is used to declare the visual representation of a data item that appears within an application’s logical tree. In ‘P’ is for Panel, we learned that an ItemsPanelTemplate is used to declare the items host used within an ItemsControl."
For my issue, I still have not successfully navigated the visual tree in order to get a reference to my splitter item. This is my best attempt so far:
// w1 is a Window
SuperTabControlEx stc = w1.FindName("superTabControl1") as SuperTabControlEx;
//SuperTabItem sti = (SuperTabItem)(stc.ItemContainerGenerator.ContainerFromItem(stc.Items.CurrentItem));
ContentPresenter myContentPresenter = FindVisualChild<ContentPresenter>(stc);
//ContentPresenter myContentPresenter = FindVisualChild<ContentPresenter>(sti);
DataTemplate myDataTemplate = myContentPresenter.ContentTemplate;
The above code is an attempt to implement the techniques shown on the msdn web site. However, when I apply it to my code, everything looks good, except myDataTemplate comes back null. As you can see, I attempted the same technique on SuperTabControlEx and SuperTabItem, derived from TabControl and TabItem, respectively. As described in my original post, and evident in the XAML snippet, the SuperTabControlEx also implements code from Keeping the WPF Tab Control from destroying its children.
At this point, perhaps more than anything else, I think this is an exercise in navigating the Visual Tree. I am going to modify the title of the question to reflect my new conceptions of the issue.
What I'd like is a control that functions just like the tab control but instead of having the tabs along the top, the items would be displayed in a list box along the side. I imagine it's possible but haven't found any examples, I'm hoping there's someone here that's done something like this.
WPF controls are designed to enable exactly what you want. To reuse control functionality while completely replacing the visual representation. You will have to create your own ControlTemplate for the TabControl. You can find a TabControl ControlTemplate Example on MSDN. You will also have to study the Control Authoring Overview on MSDN.
I actually find the Silverlight 3 documentation somewhat easier to digest, and even though there are some differences when it comes to control styling the fundamental concepts are still the same. You can read Customizing the Appearance of an Existing Control by Using a ControlTemplate on MSDN to learn about control templates and then study TabControl Styles and Templates to discover what is required to create you own control template in Silverlight.
You can use Expression Blend to extract the the default TabControl template in WPF.
You don't need to use a TabControl at all. You could just bind your ListBox to a list of items, and put a ContentControl beside it, bound to the selected item :
<DockPanel>
<ListBox Name="listBox"
DockPanel.Dock="Left"
ItemsSource="{Binding Items}"
DisplayMemberPath="Name"/>
<ContentControl Content="{Binding SelectedItem, ElementName=listBox}"
ContentTemplate="{StaticResource theTemplate}"/>
</DockPanel>