I've created a custom control that I insert into my window with the following code
<controls:ListExpander Text="Class Diagrams"></controls:ListExpander>
The control in question contains several subcontrols, among others, a list. How can create the setup, so I can specify items that should be added to the list? Eventually I'm looking for the following architecture
<controls:ListExpander Text="Class Diagrams">
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
</controls:ListExpander>
in which case the SomeItem objects should be added to the list in the ListExpander:
<ListBox Name="lstItems" Background="LightGray">
<ListBox.Items>
// Items should go here
</ListBox.Items>
</ListBox>
I'm quite new to WPF, but I suppose it's something along the lines of creating a dependency collection on ListExpander that takes object of the type SomeItem?
Edit: Let me clarify a bit. I simply want to be able to give the control a few arguments which it can translate into items in the listbox contained within the the control.
Have you created your class for ListExpander? You can inherit all functionality of an ItemsControl very simply. Here is a sample class I created for you to model it after.
CLASS
using System.Windows.Controls;
namespace ListExpanderSample
{
public class ListExpander : ItemsControl
{
static ListExpander()
{
/* Required logic goes here */
}
}
}
IMPLEMENTATION
<Grid>
<Grid.Resources>
<Style x:Key="{x:Type local:ListExpander}" TargetType="{x:Type local:ListExpander}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ListExpander}">
<Border Background="Transparent" >
<ScrollViewer Focusable="False" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto">
<ItemsPresenter />
</ScrollViewer>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
<local:ListExpander>
<local:ListExpander.Items>
<Button Content="Button 1"/>
<TextBox Text="TextBox 1"/>
<Button Content="Button 2"/>
<TextBox Text="TextBox 2"/>
</local:ListExpander.Items>
</local:ListExpander>
</Grid>
SCREENSHOT
Sample ListExpander http://lh4.ggpht.com/_jvamiP47SsA/SsWM6xN_3BI/AAAAAAAAAkg/tZUWxzi9wVI/s800/Window1.jpg
I hope this helped you out, Qua.
I assume your control contains more than just these children you are looking to add, right? So I would go by adding a property to your control class like this:
private ObservableCollection<UIElement> _items = new ObservableCollection<UIElement>();
public ObservableCollection<UIElement> Items
{
get { return this._items; }
}
Then in your controls template you just bind your listbox to this collection
<ListBox Name="lstItems" Background="LightGray" ItemsSource="{Binding Items}">
</ListBox>
This way you'll be able to use it like this:
<controls:ListExpander Text="Class Diagrams">
<controls:ListExpander.Items>
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
<SomeItem>data<SomeItem>
</controls:ListExpander.Items>
</controls:ListExpander>
To be able to use it without the <controls:ListExpander.Items> decorate your class with [ContentProperty("Items")] attribute.
There's a simple way to do it. Add a property of type ItemCollection to your control class like this:
public ItemCollection Items{
get{
return innerItems.Items;
}set{
innerItems.Items.Clear();
foreach (var item in value){
innerItems.Items.Add(item);
}
}
}
where innerItems is just an ItemsControl in your XAML (like this):
<UserControl x:Class="TestApp.ItemsExtender"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="300" Width="300">
<StackPanel>
<Label Content="Control Label" />
<ItemsControl x:Name="innerItems" />
</StackPanel>
</UserControl>
then add an attribute to your control class like this:
[ContentProperty("Items")]
public partial class ItemsExtender : UserControl
{...}
this will tell XAML that default items should be assigned to your Items property, and your Items property will use them to populate your inner list collection. You can then consume it like this:
<this:ItemsExtender>
<Label Content="item1" />
<Label Content="item2" />
<Label Content="item3" />
</this:ItemsExtender>
You can extend this sample with type converters to support adding arbitrary things to the collection and dependency properties to support binding, but this should get you started.
Hope it helps!
Related
For example I have a UserControl like this:
<UserControl x:Class="SMPlayer.ScrollingTextBlock">
<ScrollViewer
x:Name="TextScrollViewer"
HorizontalScrollBarVisibility="Hidden"
PointerEntered="TextScrollViewer_PointerEntered"
VerticalScrollBarVisibility="Disabled">
<StackPanel>
<TextBlock x:Name="NormalTextBlock" />
<TextBlock x:Name="PointerOverTextBlock" Visibility="Collapsed" />
</StackPanel>
</ScrollViewer>
</UserControl>
I want this UserControl still to be treated as a normal TextBlock. For example <ScrollingTextBlock Text="Something"/>. It is just a TextBlock with more functionalities, or in other words, another control that inherits from TextBlock. Because there are a lot of properties, I don't want to do this manually by adding DependencyProperty and do things like public string Text { get; set; }. It is just too much work.
How can I achieve that? I think this question might have been asked but I am not sure how to properly paraphrase it.
If you want to implement <ScrollingTextBlock Text="Something"/> in UserControl, you still need to add DependencyProperty to achieve it.
If you want your control to "be treated as a normal TextBlock", then you don't have any other choice than inheriting from TextBlock. This is what inheritance is for.
Otherwise you indeed have to add properties to your UserControl and bind them by yourself, even though this is a lot of work this is due to the poor flexibility of the UserControl. You cannot have a Text property on an object unless it inherits from a TextBlock or you add it yourself.
Alternatively you can use templating to re-template a ContentControl like this:
public class ScrollingContent : ContentControl { }
<Window.Resources>
<Style TargetType="local:ScrollingContent">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:ScrollingContent">
<ScrollViewer
x:Name="TextScrollViewer"
HorizontalScrollBarVisibility="Hidden"
VerticalScrollBarVisibility="Disabled">
<StackPanel>
<TextBlock x:Name="NormalTextBlock" />
<ContentPresenter></ContentPresenter>
</StackPanel>
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<Grid>
<local:ScrollingContent>
<TextBlock Text="Whatever control I want" Foreground="Red"></TextBlock>
</local:ScrollingContent>
</Grid>
But then again, your control is not really a TextBlock.
I have a ListBox that presents a databound list of objects via its ItemSource. Because each object has special display needs I’m defining an ItemTemplateSelector that returns the appropriate DataTemplate depending on the object. That all works without a hitch.
The DataTemplates for each object follow a common formula, but contains custom elements in the middle. For example:
<DataTemplate x:Key="collectibleTemplate">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Border BorderBrush="LightGray" BorderThickness="1">
<Expander IsExpanded="True" Header="{Binding ComponentName}" Background="WhiteSmoke">
<StackPanel>
<TextBlock Margin="5,5,5,0" Text="{Binding EditDescription}" TextWrapping="Wrap" />
<!-- This is the only custom part of each template -->
<StackPanel Margin="0,10,5,0" Orientation="Horizontal">
<Label Content="Type:" />
<ComboBox Height="22" HorizontalAlignment="Left" SelectedItem="{Binding Path=CollectibleType, Mode=TwoWay}"
ItemsSource="{Binding Source={StaticResource collectibleTypeFromEnum}}" />
</StackPanel>
<!-- End custom part -->
<StackPanel Margin="0,0,0,5">
<Label Content="Available Actions:" >
<Label.Style>
<Style TargetType="Label">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding EditActions.Count}" Value="0">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>
</Label>
<ItemsControl ItemsSource="{Binding EditActions}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Command="{Binding}" Content="{Binding Title}" ToolTip="{Binding ToolTip}" Margin="5,0,5,0"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</StackPanel>
</StackPanel>
</Expander>
</Border>
</Grid>
</DataTemplate>
As you can see there’s lots of shared XAML, wrapping a small custom section in the middle.
Additional data templates will be written by other engineers (they’ll want to create one for each new object type that they add), so I’m interested in making the creation of a new DataTemplate as fool-proof and painless as possible. No copying of the entire DataTemplate with the custom “stuff” added in the middle, of course – but I’m also not partial to extracting parts of the template as reusable parts and referencing them in because it still leads to lots of duplicate code in each new DataTemplate, and that means possible errors and hard maintainability. I.e., this right here is a more maintainable approach but still feels suboptimal:
<DataTemplate x:Key="collectibleTemplate">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Border BorderBrush="LightGray" BorderThickness="1">
<Expander IsExpanded="True" Header="{Binding ComponentName}" Background="WhiteSmoke">
<StackPanel>
<TextBlock Margin="5,5,5,0" Text="{Binding EditDescription}" TextWrapping="Wrap" />
<!-- This is the only custom part of each template -->
[...]
<!-- End custom part -->
<ContentPresenter Content="{StaticResource AvailableActions}" />
</StackPanel>
</Expander>
</Border>
</Grid>
</DataTemplate>
<StackPanel Margin="0,0,0,5" x:Key="AvailableActions" x:Shared="false">
<Label Content="Available Actions:" >
<Label.Style>
<!--
[Bottom half of shared XAML from the first example, offloaded here]
-->
</StackPanel>
So: what is my best strategy to solve this? AFAIK I’m stuck with using DataTemplates because that’s the only element that a ListBox ItemTemplateSelector accepts. Is there a way to create a compound DataTemplate in the DataTemplateSelector? I'd provide the stock DataTemplate that is shared by all objects, and the DataTemplateSelector references in the bit of custom XAML needed for each object type. Other engineers would hook into that generalized code behavior.
Not sure, fumbling a bit in the dark here as whether there is a pattern that allows me to solve this elegantly.
And, just for reference: my current DataTemplateSelector is super straightforward. This is where I would expect to construct the final DataTemplate, rather than simply returning one that's hardcoded in XAML.
public class NodeComponentDataTemplateSelector : DataTemplateSelector
{
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
FrameworkElement element = container as FrameworkElement;
if (element != null && item != null)
{
if (item is CollectibleComponent)
return element.FindResource("collectibleTemplate") as DataTemplate;
// [...]
}
}
}
You could create the DataTemplate dynamically using the XamlReader.Parse or XamlReader.Load method, e.g.:
string template = "<DataTemplate xmlns =\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\" xmlns:x =\"http://schemas.microsoft.com/winfx/2006/xaml\"><StackPanel>[PLACEHOLDER]</StackPanel></DataTemplate>".Replace("[PLACEHOLDER]", "...custom code...");
return System.Windows.Markup.XamlReader.Parse(template) as DataTemplate;
The custom parts could be defined as UserControls.
I am afraid there is no way to base a DataTemplate on another one in pure XAML though.
You could create a new CustomControl that fits your needs. It will apply the style by itself and you can give additional DepdendencyProperties to make it more convinient. In the end you can still put it in a DataTemplate to use it with your DataTemplateSelector.
i want to have a user UserControl derived class with a List of objects of another UserControl derived class which i can use in xaml.
<UserControlA>
<UserControlA.Items>
<UserControlB Width=10 Height=10 />
<UserControlB Width=10 Height=10 />
<UserControlB Width=10 Height=10 />
<UserControlA.Items>
<UserControlA>
I don't know how to implement the Items Property of UserControlA to allow this. I already tried to implemet it as a dependency property of type Items : List<UserControlB> but this does copy the whole xaml from USerControlB into the UserControlA.Items section.
Thanks for any Help
It really looks like you are "over-doing" it. You may just want to Style or Template an ItemsControl or ListBox and DataTemplate the Items within.
Here's some code:
<ListBox>
<ListBox.Template>
<ControlTemplate>
<!--The control functionality of UserControlA-->
<ItemsPresenter/>
</ControlTemplate>
</ListBox.Template>
<ListBox.ItemTemplate>
<DataTemplate>
<ContentControl/> <!--UserControlB-->
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Is there some way to apply styles to the first (or last or nth) child of a container (anything that contains children)? I am trying to customize the look of tab items so that the first one has different border radius than the others.
This is what I have now:
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid>
<Border Name="Border" BorderBrush="#666" BorderThickness="1,1,1,0" CornerRadius="8,8,0,0" Margin="0,0,0,-1">
<TextBlock x:Name="TabItemText" Foreground="#444" Padding="6 2" TextOptions.TextFormattingMode="Display">
<ContentPresenter x:Name="ContentSite" VerticalAlignment="Center" HorizontalAlignment="Center" ContentSource="Header" Margin="12,2,12,2"/>
</TextBlock>
</Border>
</Grid>
</ControlTemplate>
For ItemsControl derived classes (such as TabControl), you can use the ItemContainerStyleSelector dependency property. When this dependency property is set, ItemsControl will call StyleSelector.SelectStyle() for each item in the control. This will allow you to use different styles for different items.
The following example changes the last tab item in a TabControl so its text is bold and a bit larger than the other tabs.
First, the new StyleSelector class:
class LastItemStyleSelector : StyleSelector
{
public override Style SelectStyle(object item, DependencyObject container)
{
var itemsControl = ItemsControl.ItemsControlFromItemContainer(container);
var index = itemsControl.ItemContainerGenerator.IndexFromContainer(container);
if (index == itemsControl.Items.Count - 1)
{
return (Style)itemsControl.FindResource("LastItemStyle");
}
return base.SelectStyle(item, container);
}
}
This style selector will return the style with the key "LastItemStyle" but only for the last item in the control. The other items will use the default style. (Note, that this function only uses members from ItemsControl. It could also be used for other ItemsControl derived classes.) Next, in your XAML, you first need to create two resources. The first resource will be to this LastItemStyleSelector and the second resource is the style.
<Window.Resources>
<local:LastItemStyleSelector x:Key="LastItemStyleSelector" />
<Style x:Key="LastItemStyle" TargetType="TabItem">
<Setter Property="FontWeight" Value="Bold" />
<Setter Property="FontSize" Value="16" />
</Style>
</Window.Resources>
Then finally your TabControl:
<TabControl ItemContainerStyleSelector="{StaticResource LastItemStyleSelector}">
<TabItem Header="First" />
<TabItem Header="Second" />
<TabItem Header="Third" />
</TabControl>
For more information see the MSDN documentation:
ItemsControl.ItemContainerStyleSelector Property
StyleSelector Class
Unlike HTML and CSS, there's not a simple way to determine and trigger that type of change.
You could potentially write a trigger and use a value converter to do something like that using this forum post as inspiration potentially.
Much simpler would be to apply a custom style to the tabitem that you want to look different. Have you tried that?
<TabItem Header="TabItem" Style="{DynamicResource FirstTabStyle}">
<Grid Background="#FFE5E5E5"/>
</TabItem>
I have a general question about data templates in WPF. Let's say I have an abstract class called "Question," and various subclasses like "MathQuestion," "GeographyQuestion," etc. In some contexts, rendering the questions as a "Question" using the "Question" data template is good enough, but let's say that I have a list of random Question objects of varying subclasses that I want to display in-turn. I want to display them to the user using their specific data templates rather than their generic Question data template, but since I don't know that at design time, is there anyway to tell WPF, "hey, here's a list of Quesitons, but use reflection to figure out their specific types and use THAT data template?"
What I've thought of so far: I thought that in addition to having my question collection, I could create another collection of the specific types using reflection and somehow bind that to "blah," then I'd get the desired affect, but you can only bind to DependencyProperties in WPF, so I'm not sure what I'd bind to. I really don't like this idea, and my gut tells me there's a more elegant way to approach this problem.
I'm not looking for specific code here, just a general strategy to accomplish what I'm trying to do. Also, I'm using MVVM for the most part if that helps.
Thanks
I'm thinking something like this should work right out of the box:
<UserControl.Resources>
<DataTemplate DataType="{x:Type vm:GenericQuestionViewModel}">
<v:GenericQuestion/>
</DataTemplate>
<DataTemplate DataType="{x:Type tvm:GeographyQuestionViewModel}">
<tv:GeographyQuestion/>
</DataTemplate>
<DataTemplate DataType="{x:Type tvm:BiologyQuestionViewModel}">
<tv:BiologyQuestion/>
</DataTemplate>
</UserControl.Resources>
<ContentControl Content="{Binding QuestionViewModel}">
Edit:
Yes, this definitely should work. Here's a more complete example:
Main View Model
public class MainWindowViewModel : ViewModelBase
{
public ObservableCollection<QuestionViewModel> QuestionViewModels { get; set; }
public MainWindowViewModel()
{
QuestionViewModels = new ObservableCollection<QuestionViewModel>
{
new GenericQuestionViewModel(),
new GeographyQuestionViewModel(),
new BiologyQuestionViewModel()
};
}
}
Question View Models
public abstract class QuestionViewModel : ViewModelBase
{
}
public class GenericQuestionViewModel : QuestionViewModel
{
}
public class GeographyQuestionViewModel : QuestionViewModel
{
}
public class BiologyQuestionViewModel : QuestionViewModel
{
}
Question User Controls
<UserControl x:Class="WpfApplication1.GenericQuestion" ...>
<Grid>
<TextBlock Text="Generic Question" />
</Grid>
</UserControl>
<UserControl x:Class="WpfApplication1.GeographyQuestion" ...>
<Grid>
<TextBlock Text="Geography Question" />
</Grid>
</UserControl>
<UserControl x:Class="WpfApplication1.BiologyQuestion" ...>
<Grid>
<TextBlock Text="Biology Question" />
</Grid>
</UserControl>
Main Window
<Window x:Class="WpfApplication1.MainWindow" ...
Title="MainWindow"
Height="900"
Width="525">
<Window.DataContext>
<local:MainWindowViewModel />
</Window.DataContext>
<Window.Resources>
<DataTemplate DataType="{x:Type local:GenericQuestionViewModel}">
<local:GenericQuestion />
</DataTemplate>
<DataTemplate DataType="{x:Type local:GeographyQuestionViewModel}">
<local:GeographyQuestion />
</DataTemplate>
<DataTemplate DataType="{x:Type local:BiologyQuestionViewModel}">
<local:BiologyQuestion />
</DataTemplate>
</Window.Resources>
<ItemsControl ItemsSource="{Binding QuestionViewModels}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ContentControl Content="{Binding}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Window>
Update
Kyle Tolle pointed out a nice simplification for setting ItemsControl.ItemTemplate. Here is the resulting code:
<ItemsControl ItemsSource="{Binding QuestionViewModels}"
ItemTemplate="{Binding}" />
Generally, if you need to dynamically change the DataTemplate based on some non-static logic, you'd use a DataTemplateSelector. Another option it to use DataTriggers in your DataTemplate to modify the look appropriately.