Is it not possible to have multiple layers of UserControls containing ContentControl?
I am trying to create Views for different Models that are derived, so I'd like to eliminate the need to re-create the Views for each object type, and instead provide a ContentControl, or a ContentPresenter to inject the "rest of the view". However, I can only go one level deep with this method.
Here's a simplified example.(I've removed some of the xmlns). In my case, I'm working with significantly more complex Views, and trying to eliminate duplicate code in multiple places, concerned for changes later.
I have a Base UserControl, we'll call it UserControlLevel1
<UserControl x:Class="ContentControlNesting.UserControlLevel1"
x:Name="userControlLevel1"
xmlns:local="clr-namespace:ContentControlNesting">
<StackPanel>
<TextBlock Text="UserControlLevel1ContentTop"/>
<ContentControl Content="{Binding ElementName=userControlLevel1, Path=ChildContent}"/>
<TextBlock Text="UserControlLevel2ContentBottom"/>
</StackPanel>
</UserControl>
It has the following DependencyProperty on the UserControl
namespace ContentControlNesting
{
public partial class UserControlLevel1 : UserControl
{
public UserControlLevel1()
{
InitializeComponent();
}
public static readonly DependencyProperty ChildContentProperty = DependencyProperty.Register("ChildContent", typeof(UIElement), typeof(UserControlLevel1), new PropertyMetadata(null));
public UIElement ChildContent
{
get { return (UIElement)GetValue(ChildContentProperty); }
set { SetValue(ChildContentProperty, value); }
}
}
}
The ContentControl will be used in the following UserControl called UserControlLevel2. This UserControl works fine, just the way I would expect. Or rather UserControlLevel1 works properly within UserControlLevel2.
<UserControl x:Class="ContentControlNesting.UserControlLevel2"
x:Name="userControlLevel2"
xmlns:local="clr-namespace:ContentControlNesting">
<local:UserControlLevel1>
<local:UserControlLevel1.ChildContent>
<StackPanel>
<TextBlock Text="UserControlLevel2ContentTop"/>
<ContentControl Content="{Binding ElementName=userControlLevel2, Path=ChildContent}"/>
<TextBlock Text="UserControlLevel2ContentBottom"/>
</StackPanel>
</local:UserControlLevel1.ChildContent>
</local:UserControlLevel1>
</UserControl>
Likewise, it has a single DependencyProperty for the ContentControl on this UserControl like the first. I've also tried this with differently named DependencyProperties.
namespace ContentControlNesting
{
public partial class UserControlLevel1 : UserControl
{
public UserControlLevel1()
{
InitializeComponent();
}
public static readonly DependencyProperty ChildContentProperty = DependencyProperty.Register("ChildContent", typeof(UIElement), typeof(UserControlLevel1), new PropertyMetadata(null));
public UIElement ChildContent
{
get { return (UIElement)GetValue(ChildContentProperty); }
set { SetValue(ChildContentProperty, value); }
}
}
}
Okay, so at this point, everything seems to be working fine. I've added additional content inside of the ContentControl of UserControlLevel1, and I've added another ContentControl within my UserControlLevel2 UserControl.
The problem is when I try to introduce a 3rd Tier of either UserControl or my MainWindow. Anything I add to the ContentControl of UserControlLevel2 just does not appear.
<Window x:Class="ContentControlNesting.MainWindow"
xmlns:local="clr-namespace:ContentControlNesting"
Title="MainWindow" Height="200" Width="300">
<local:UserControlLevel2>
<local:UserControlLevel2.ChildContent>
<StackPanel>
<TextBlock Text="Main Window Content Text"/>
</StackPanel>
</local:UserControlLevel2.ChildContent>
</local:UserControlLevel2>
</Window>
Am I trying to do something that's not possible? Or am I doing something wrong with ContentControl and the DependencyProperties? Should I be looking at this with a different approach?
It is possible. The system cannot resolve the ElementName in the Binding. The solution is to use the relative binding. Just replace the following line in UserControlLevel2 and your are done:
<ContentControl Content="{Binding Path=ChildContent, RelativeSource={RelativeSource AncestorType={x:Type local:UserControlLevel2}}}"/>
Related
I'm totally lost with dependancy objects and binding. I often get things working without understanding why and how, this question is about knowing what should be happening.
I have a tiny user control with the following XAML
<Grid>
<Image Source="{Binding Icon}"></Image>
<TextBlock Text="{Binding Title}"></TextBlock>
</Grid>
My code behind has the following
public static readonly DependencyProperty IconProperty =
DependencyProperty.Register("Icon", typeof(Image), typeof(MenuItem));
public Image Icon
{
get { return (Image)GetValue(IconProperty); }
set { SetValue(IconProperty, value); }
}
public static readonly DependencyProperty TitleProperty =
DependencyProperty.Register("Title", typeof(String), typeof(MenuItem));
public string Title
{
get { return (string)GetValue(IconProperty); }
set { SetValue(IconProperty, value); }
}
My MainWindow is empty, other than a reference to this control and to the ResourceDictionary. In the MainWindow code behind, I set the DataContext in the constructor.
<Window x:Class="AppUi.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:loc="clr-namespace:AppUi.Control"
Title="">
//set up to Resource Dictionary - all binding and styling works fine :)
<loc:MenuItem Icon="{Binding MailIcon}" Title="{Binding MailTitle}"></loc:MenuItem>
In the ModelView for the MainWindow, I have the following 2 properties
private Image_mailIcon;
public Image MailIcon{
//inotifyproperty implementation
}
private string _mailTitle;
public string MailTitle{
//inotifyproperty implementation
}
My question is, in the UserControl, how do I do the binding? Since it's a user control within a MainWindow, and the MainWindow already has a datacontext, I think the UserControl will inherit the DataContext from the parent (From what I have read).
So, in my UserControl XAML, should I be binding to the MainWindow's Code Behind properties OR to the ViewModel properties?
In other words, should my UserControl be
<Grid>
<Image Source="{Binding MailIcon}"></Image>
<TextBlock Text="{Binding MailTitle}"></TextBlock>
</Grid>
OR
<Grid>
<Image Source="{Binding Icon}"></Image>
<TextBlock Text="{Binding Title}"></TextBlock>
</Grid>
Or, because I'm using a DataContext and the UserControl inherits, do I even need the Dependancy Properties at all?
You normally don't want to overwrite DataContext passed through visual tree so you can use either ElementName or RelativeSource binding inside UserControl to change binding context. The easiest way to achive this is give UserControl some name and use it ElementName binding
<UserControl ... x:Name="myUserControl">
<!-- ... -->
<Grid>
<Image Source="{Binding Icon, ElementName=myUserControl}"/>
<TextBlock Text="{Binding Title, ElementName=myUserControl}"/>
</Grid>
<!-- ... -->
</UserControl>
This way binding is DataContext independent. You can also create UserControl with assumption it will always work with only specific type of DataContext and then you just use Path from that view model type but then DataContext of that UserControl must always be of the view model it's designed for (mostly inherited through visual tree)
<UserControl ...>
<!-- ... -->
<Grid>
<Image Source="{Binding MailIcon}"/>
<TextBlock Text="{Binding MailTitle}"/>
</Grid>
<!-- ... -->
</UserControl>
I would also change type of Icon property from Image to ImageSource for example. You already have Image control inside your UserControl and you just want to bind its Source
in the UserControl, how do I do the binding? ... the UserControl will inherit the DataContext from the parent
That is correct, the UserControl will inherit the DataContext from the parent Window. Therefore you can data bind from the UserControl directly to the parent Window.DataContext. Please note that you would bind to whatever object has been set as the DataContext, regardless of whether that was the code behind or a separate view model class.
However, you don't have to data bind to the parent's DataContext object in this situation... you have other options. You could data bind to your own UserControl DependencyPropertys using a RelativeSource Binding like this:
<TextBlock Text="{Binding Title, RelativeSource={RelativeSource
AncestorType={x:Type YourPrefix:YourUserControl}}}" />
You could also name your UserControl and reference its properties like this:
<TextBlock Text="{Binding Title, ElementName=YourUserControlName}" />
While this example seems to be more concise, don't overlook the first example, as RelativeSource is a useful and powerful friend to have.
should I be binding to the MainWindow's Code Behind properties OR to the ViewModel properties?
That's your choice... what do you want or need to data bind to? you just need to know that a direct data binding will use the auto set DataContext value, so if you don't want to use that, then you can just specify a different data source for the Binding as shown above.
Finally, regarding the need to use DependencyPropertys... you only need to declare them if you are developing a UserControl that needs to provide data binding abilities.
I'm having some issues with binding some custom controls in a Windows Phone app right now. Usually this is never an issue but apparently my mind can't comprehend this today.
So I'm doing an MVVM style setup which is good. I have my page with a view and also a viewmodel. Now on a WebClient callback I assign the dataContext of my view to the list of models in my ViewModel, nice and simple thus far...now in my view I created a ListBox with a custom control in the datatemplate which is basically a cell in the list. I once again set my user controls dataContext to binding, and binding all the models values to the regular UI elements works no problem.
Here's a sample:
<Grid Grid.Column="0">
<Image Source="{Binding SmallPath}" VerticalAlignment="Top"/>
</Grid>
<Grid Grid.Column="1">
<StackPanel Margin="12,0,0,0">
<TextBlock x:Name="MemberId_TextBlock" Text="{Binding MemberId}" FontSize="28"
Margin="0,-8,0,0"
Foreground="{StaticResource PhoneForegroundBrush}"/>
<StackPanel Orientation="Horizontal" Margin="0,-11,0,0">
<TextBlock Text="{Binding DaysReported}" FontSize="42"
Margin="0,0,0,0"
Foreground="{StaticResource PhoneAccentBrush}"/>
<TextBlock Text="days" FontSize="24"
Margin="3,19,0,0"
Foreground="{StaticResource PhoneSubtleBrush}"/>
</StackPanel>
</StackPanel>
</Grid>
That's in my user control, and here's the the view where the usercontrol is housed:
<Grid x:Name="LayoutRoot" Background="Transparent">
<ListBox Name="TopSpotter_ListBox" ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<!--<TextBlock Text="{Binding MemberId}"/>-->
<controls:TopSpotterItemControl DataContext="{Binding}"/>
<Grid Height="18"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
Now this is good enough but what I want to do in my view is set data from my model like Booleans that determine whether or not I should show certain Grids etc. So if I try to set a dependency property explicitly in my control it fires and will run logic in the Getter/Setters for instance. HOWEVER if I try to set these custom objects from a binding source it won't actually set.
Here's what works:
<controls:TopSpotterItemControl ChampVisibility="True">
This way will trigger the ChampVisibility property and then in the code behind of the user control I can set visibilities.
Here's what fails but I want to work:
<controls:TopSpotterItemControl ChampVisibility="{Binding IsChamp">
In addition I can still set the DataContext to {Binding} and the result will be unchanged.
In this scenario IsChamp is part of my model that I would like to bind to this user control which I guess comes from the dataContext being set on the view from the viewModel. I'm not sure what I can do to get this so the bindings work etc. without having to set custom properties.
Finally, here's my user control:
public partial class TopSpotterItemControl : UserControl
{
public string MemberId
{
get
{
return this.MemberId_TextBlock.Text;
}
set
{
this.MemberId_TextBlock.Text = value;
}
}
public bool ChampVisibility {
set
{
if (value)
{
this.Champ_Grid.Visibility = System.Windows.Visibility.Visible;
}
}
}
public static readonly DependencyProperty MemberNameProperty =
DependencyProperty.Register("MemberId", typeof(string), typeof(TopSpotterItemControl), new PropertyMetadata(null));
public static readonly DependencyProperty ChampVisibilityProperty =
DependencyProperty.Register("ChampVisibility", typeof(bool), typeof(TopSpotterItemControl), new PropertyMetadata(null));
public TopSpotterItemControl()
{
InitializeComponent();
}
}
Bit long winded and I hope I made things on the issue clear. My one major hang up so far, and I'd like to abstract as much control as I can to the user control via dependency properties explicitly set in xaml, rather than setting up binding in its xaml that depend on the knowledge of a model. Thanks!
Your DependencyProperty is badly formed. (I also don't see Champ_Grid defined in your class or XAML, but I assume that is an ommission)
Setting ChampVisibility = true in code works because it is unrelated to the DependencyProperty.
You can tell easily because the default value for your DP is invalid. It will compile, but the instance constructor will through an exception if it is ever invoked.
new PropertyMetadata(null)
bool = null = exception
If you call GetValue(TopSpotterItemControl.ChampVisibilityProperty) from somewhere you can confirm all of the above.
You should make changes to instance fields in the property changed handler and declare the property like the following, it will work:
Note that the property has to change (not just be set) for the event to be raised.
public bool ChampVisibility
{
get { return (bool)GetValue(ChampVisibilityProperty); }
set { SetValue(ChampVisibilityProperty, value); }
}
public static readonly DependencyProperty ChampVisibilityProperty =
DependencyProperty.Register("ChampVisibility ", typeof(bool), typeof(TopSpotterItemControl), new PropertyMetadata(true, (s, e) =>
{
TopSpotterItemControl instance = s as TopSpotterItemControl;
instance.Champ_Grid.Visibility = instance.ChampVisibility ? System.Windows.Visibility.Visible : System.Windows.Visibility.Collapsed;
}));
Incidentally, your MemberId DependencyProperty is also completely wrong and cannot work.
Note:
The Binding on your TextBox works, because it is binding to the DataContext (your model), so it probably shows the right value.
The Dependency property in your UserControl will never be set though.
Use the propdp code-snippet in Visual Studio so you dont have to concern yourself with the complexities of Dependency Property declaration.
Also check this out for more info about Dependency Properties
in my Silverlight 4 app, I try to create a simple UserControl, which will be consumed by my Application. To keep things simple, it shall have a "header" and a placeholder, where I want to place any kind of control.
<User Control ...>
<Grid x:Name="LayoutRoot">
<TextBlock x:Name="TextBlockHeader" Text="{Binding Title}" />
<ContentPresenter x:Name="ContentPresenterObject" />
</Grid>
</UserControl>
In the code behind, I have created a property for the text of the TextBlock
public string Title
{
get { return (string)GetValue(TitleProperty); }
set { SetValue(TitleProperty, value); }
}
public static readonly DependencyProperty TitleProperty = DependencyProperty.Register("Title", typeof(string), typeof(MyAccordion), null);
This way, I can set the Title property, when I use the Control in my application.
<local:MyAccordion Title="Test"/>
But it seems, that the binding at the textblock Text="{Binding Title}" doesn't make the text "Test" to be displayed as the textblocks text.
My question is: How can I make the Property Title to be displayed as the textboxes text and how do I do this for the - any type of user control containable - contencontrol?
Thanks in advance,
Frank
Maybe DataContext of control or page was not set. - First of all you should read more about a Binding ("http://www.silverlight.net/learn/data-networking/binding/data-binding-to-controls-(silverlight-quickstart)"). If you are working on real project and will design a some arhitecture, you should read about MVVM pattern.
The answer is ElementPropertyBinding. I need to reference the User Control in the Binding or add the binding in the constructor.
Create the binding in XAML:
<User Control ... x:Name="userControl">
...
<TextBlock x:Name="TextBlockHeader" Text="{Binding Title, ElementName=userControl}" />
</UserControl>
Create the binding in the constructor (Code behind)
public MyUserControl()
{
// Required to initialize variables
InitializeComponent();
TextBlockHeader.SetBinding(TextBlock.TextProperty, new System.Windows.Data.Binding() { Source = this, Path = new PropertyPath("Title") });
}
I still need to find out how to add a child control, but that's another question.
I have created a user control that consists of a expander, listbox and checkboxes. I am not able to access the checkboxes (child control) and I want to generate the number of expanders based on the number of rows in a table dynamically. Can anyone suggest the possible solutions to
This is extremely vague. In most cases you would just expose some of the internal control's properties, e.g. if you want to create dynamic content you would expose the ItemsSource and ItemTemplate of an internal ListBox of whatever you use so it can be set from outside, e.g.
<UserControl x:Class="Test.UserControls.Bogus" 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" Name="control">
<StackPanel>
<TextBlock Text="Lorem Ipsum:" />
<ItemsControl ItemsSource="{Binding ElementName=control, Path=ItemsSource}"
ItemTemplate="{Binding ElementName=control, Path=ItemTemplate}" />
</StackPanel>
</UserControl>
public partial class Bogus : UserControl
{
public static readonly DependencyProperty ItemsSourceProperty = ItemsControl.ItemsSourceProperty.AddOwner(typeof(Bogus));
public IEnumerable ItemsSource
{
get { return (IEnumerable)GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
public static readonly DependencyProperty ItemTemplateProperty = ItemsControl.ItemTemplateProperty.AddOwner(typeof(Bogus));
public DataTemplate ItemTemplate
{
get { return (DataTemplate)GetValue(ItemTemplateProperty); }
set { SetValue(ItemTemplateProperty, value); }
}
public Bogus()
{
InitializeComponent();
}
}
Usage:
<uc:Bogus ItemsSource="{Binding Data}">
<uc:Bogus.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" Foreground="Red" />
</DataTemplate>
</uc:Bogus.ItemTemplate>
</uc:Bogus>
You can of course also encapsulate a lot of logic which you do not need exposed.
Since you want a varying amount of expanders you might have an ItemsControl (unlike a ListBox it has no selection) which already defines an ItemTemplate which contains an expander. You probably can also create a partial template as shown in this answer of mine.
Sounds like you need to navigate the visual tree. The simplest way of doing this is via Linq-to-VisualTree. To find all the CheckBoxes that are a child of 'this', use the following query:
IEnumerable<CheckBox> checks = this.Descendants<CheckBox>().Cast<CheckBox>();
Your application is running in an Application instance. Access the usercontrol components with Application.usercontrol.ComponentName if it is not a UI update. If you make UI updates, you have to run the access in a separate dispatcher thread. In that case, use BackgroundWorker.
For example, I am running my main application class MainWindow and accessing it as,
MainWindow rootWindow = Application.Current.MainWindow as MainWindow;
Now access the usercontrol and properties of components as:
rootWindow.usercontrolX.ComponentY.PropertyZ
Define properties in the child's class for each of those controls. You will be able to access them from the Parent User Control, assuming you have added the Child User Control within the Parent User Control.
Parent User Control.. SingalData is the child User Contol
<my:C1TabItem Header="Signal">
<local:SignalData Width="1036" OnSignalNameChange="SignalInputTab_OnSignalNameChange" Loaded="SignalInputTab_Loaded" Height="353" VerticalAlignment="Top" MinHeight="353" HorizontalAlignment="Left"></local:SignalData>
In the Child User Contorl class, if you have a component named tabProductList you add a property -
public C1.WPF.C1TabControl TabProductList
{
get { return this.tabProductList; }
}
And finally, from your parent class you can reference it as -
C1TabItem tbItem = (C1TabItem)c1TabControl1.SelectedItem;
SignalData sigInp = (SignalData)tbItem.Content;
if (sigInp.TabProductList.SelectedIndex == 0)
{
....
I am exploring the Silverlight attached behaviors mechanism in order to use the Model-View-ViewModel pattern within my Silverlight applications. To start with, I am trying to get a simple Hello World working, but I am completely stuck in an error for which I'm not able to find a solution.
What I have right now is a page that just contains a button which should display a message when clicked. The click event is handled by using a class derived from Behavior, and the message is specified as a dependency property of the behavior itself. The problem comes when trying to bind the message property to a property on a viewmodel class used as the data context: I get an exeption in the call to InitializeComponent in the view.
Here is all the code I'm using, as you can see it is rather simple. First the markup of the main page and the view it contains:
MyPage
<UserControl x:Class="MyExample.MyPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:MyExample"
>
<Grid x:Name="LayoutRoot">
<local:MyView/>
</Grid>
</UserControl>
MyView (the TextBlock is there just to check that the binding syntax is correct)
<UserControl x:Class="MyExample.MyView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:local="clr-namespace:MyExample"
Width="400" Height="300">
<StackPanel Orientation="Vertical" x:Name="LayoutRoot" Background="White">
<StackPanel.Resources>
<local:MyViewmodel x:Key="MyResource"/>
</StackPanel.Resources>
<TextBlock Text="This button will display the following message:"/>
<TextBlock Text="{Binding MyMessage, Source={StaticResource MyResource}}" FontStyle="Italic"/>
<Button x:Name="MyButton" Content="Click me!">
<i:Interaction.Behaviors>
<local:MyBehavior Message="{Binding MyMessage, Source={StaticResource MyResource}}"/>
</i:Interaction.Behaviors>
</Button>
</StackPanel>
</UserControl>
Now the code, there are two classes: one for the behavior and another one for the viewmodel:
MyViewmodel
public class MyViewmodel
{
public string MyMessage
{
get { return "Hello, world!"; }
}
}
MyBehavior
public class MyBehavior : Behavior<Button>
{
public static readonly DependencyProperty MessageProperty =
DependencyProperty.Register("Message",
typeof(string), typeof(MyBehavior),
new PropertyMetadata("(no message)"));
public string Message
{
get { return (string)GetValue(MessageProperty); }
set { SetValue(MessageProperty, value); }
}
protected override void OnAttached()
{
base.OnAttached();
AssociatedObject.Click += new RoutedEventHandler(AssociatedObject_Click);
}
protected override void OnDetaching()
{
base.OnDetaching();
AssociatedObject.Click -= new RoutedEventHandler(AssociatedObject_Click);
}
void AssociatedObject_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show(Message);
}
}
Simple enough, but this code throws an AG_E_PARSER_BAD_PROPERTY_VALUE [Line: 15 Position: 43] (right at the start of the value being set for the Message property) exception when ran. I'm sure that I'm missing something, but what?
Additional information: if I remove the binding from the Message property on MyBehavior (that is, if I set its value to any static string), it works fine. Also, I'm targeting silverlight 3 RTW.
Thanks a lot!
UPDATE
It seems that unlike WPF, Silverlight does not support data binding on any object deriving from DependencyObject, but only on objects deriving from FrameworkElement. This is no the case for Behavior, hence binding does not work.
I have found a workaround here, in the form of something named surrogate binders. Basically you specify the element and property to be binded, as well as the value, as attributes of the FrameworkElement containing the non-FrameworkElement object.
UPDATE 2
The surrogate binder does not work when the FrameworkElement contains an Interaction.Behaviors sub-element.
I have found another solution here, and this one seems to work. This time, the trick used is a DeepSetter. You define one of such setters as a static resource on the containing StackPanel, and then reference the resource from the behavior. So in my example, we should expand the StackPanel resources section as follows:
<StackPanel.Resources>
<local:MyViewmodel x:Key="MyResource"/>
<local:DeepSetter
x:Key="MyBehaviorSetter"
TargetProperty="Message"
BindingExport="{Binding MyMessage, Source={StaticResource MyResource}}"/>
</StackPanel.Resources>
...and modify the button's behavior declaration as follows:
<local:MyBehavior local:DeepSetter.BindingImport="{StaticResource MyBehaviorSetter}"/>
UPDATE 3
Good news: data binding for any DependecyObject will be available on Silverlight 4: http://timheuer.com/blog/archive/2009/11/18/whats-new-in-silverlight-4-complete-guide-new-features.aspx#dobind
To get the DataBinding support the class should inherit from FrameworkElement.Hoping MSFT will give support in Silverlight 4