could someone please explain to me what is the difference if I use
DataTemplate inside the ListView in XAML?
I have used ListView to display the content from my ObservableCollection without using DataTemplate and with DataTemplate it seems to look exactly the same?
Why then would I want to use Data Template? I would like to see a simple explanation/example.
DataTemplate is used to show data in ways beyond a simple text block. Sure doing this:
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ListView.ItemTemplate>
Doesn't buy you much. But it allows you to do stuff like this:
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel>
<Image Source="{Binding ImagePath}"/>
<TextBlock Text="{Caption}"/>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
Which is pretty cool! You can put anything inside the template, so it makes ItemsControl (and its derivatives) some of the most powerful classes in WPF.
Please take a look at #HighCore's answer here WPF MVVM Why use ContentControl + DataTemplate Views rather than straight XAML Window Views?.
<Window x:Class="MyViews.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml
xmlns:viewmodel="clr-namespace:Project.ViewModel"
DataContext="{Binding Main, Source={StaticResource Locator}}"
Title="{Binding Title, Mode=TwoWay}" Height="{Binding Height, Mode=TwoWay}" Width="{Binding Width, Mode=TwoWay}" Left="{Binding Left, Mode=TwoWay}" Top="{Binding Top, Mode=TwoWay}" WindowStartupLocation="CenterScreen">
<Window.Resources>
<HierarchicalDataTemplate DataType="{x:Type viewmodel:OtherViewModel1}">
<ContentPresenter Content="{Binding Path=Text}" />
</HierarchicalDataTemplate>
<DataTemplate DataType="{x:Type viewmodel:OtherViewModel2}">
<view:ConnectivityLED />
</DataTemplate>
</Window.Resources>
So you can see Mainwindow is talking to more than 1 viewmodel, Main is its own view model which is its datacontext and it also has reference to otherviewmodel1 and otherviewmodel2. Hope this helps, Cheers!
Related
I have a TabControl which defines some data templates to show content based on the selected tab.
<TabControl
Grid.Row="1"
ItemsSource="{Binding ExerciseViewModels}"
SelectedItem="{Binding SelectedExercise}">
<TabControl.Resources>
<DataTemplate DataType="local:SubtractExerciseViewModel">
<local:SubtractUserControl/>
</DataTemplate>
<DataTemplate DataType="local:SumExerciseViewModel">
<local:SubtractUserControl/>
</DataTemplate>
</TabControl.Resources>
<TabControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</TabControl.ItemTemplate>
</TabControl>
But when I run, the selected tab shows the name of the ViewModel (thus the DataTemplate for the specific type is not used).
What am I missing?
PS: Using MvvmLight but not really of any relevance. All the view models obviously exist (see screenshot, it has the reference to an object of type SuusRekenWonder.SumExerciseViewModel). So I am doing something wrong in XAML. But what?
In your TabControl-Resources you have to use x:Type for your DataType. Then your Resources look like:
<TabControl.Resources>
<DataTemplate DataType="{x:Type local:SubtractExerciseViewModel}">
<local:SubtractUserControl/>
</DataTemplate>
<DataTemplate DataType="{x:Type local:SumExerciseViewModel}">
<local:SubtractUserControl/>
</DataTemplate>
</TabControl.Resources>
on uwp, I want to make a hamburger menu with custom icon in xaml. from the lunch scheduler sample from MS, I try to bind a viewmodel property to a content element in a view like :
<ListBox ItemsSource="{Binding Items}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
<ListBox.ItemTemplate>
<DataTemplate x:DataType="viewmodels:MenuItem">
<StackPanel Orientation="Horizontal">
<ContentControl Content="{x:Bind Icon2}" />
where Icon is a property like
Icon2 = Application.Current.Resources["BookIcon"],
which works and retreive a viewbox containing a canvas
but I got an exception "Value does not fall within the expected range."
Did some know if it's possible like in WPF ??
nb : if i put the canvas directly in the contentcontrol, it works. perhaps the binding does not accept anything else than string
i found a solution, convert the viewbox to DataTemplate and bind to ContentTemplate
<DataTemplate x:Key="BookIcon">
<Viewbox Width="48" Height="48">
<Canvas Width="24" Height="24">
<Path Data/>
</Canvas>
</Viewbox>
</DataTemplate>
and
<ContentControl ContentTemplate="{x:Bind Icon2}"/>
any other solution is welcome
So I have a few ListViews. The first is binded to ObservaleCollection<ComPort>. All properties of ComPort may take some predefined values. Other ListViews are responsible for that properties: they show all that possible (predefined) values and SelectedItem should be the current value of that property of ComPort from the first ObservaleCollection.
I can't attach images so here is an external picture, it would make the situation clean: http://i.stack.imgur.com/ZBRRx.png
<Window.Resources>
<ResourceDictionary x:Name="rd">
<l:ComPorts x:Key="vComPorts"/>
<l:SystemPorts x:Key="vSystemPorts"/>
<l:BaudRates x:Key="vBaudRate"/>
<l:Parities x:Key="vParities"/>
<l:DataBits x:Key="vDataBits"/>
<l:StopBits x:Key="vStopBits"/>
<l:Timeouts x:Key="vTimeouts"/>
<l:ComPort x:Key="vSelectedPort"/>
</ResourceDictionary>
</Window.Resources>
...
<ListView
Name="PortsList"
Grid.Row="1"
Grid.Column="0"
Margin="5"
VerticalAlignment="Stretch"
ItemsSource="{StaticResource vComPorts}"
DataContext="{StaticResource vComPorts}"
SelectedValuePath="PortName"
SelectedValue="{Binding ElementName=SystemPortsList, Path=SelectedItem.Value}"
SelectionChanged="PortsList_SelectionChanged"
MouseDoubleClick="PortsList_MouseDoubleClick">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox />
<TextBlock Margin="5,0,0,0" Text="{Binding Path=Name}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<ListView
x:Name="SystemPortsList"
Margin="5"
VerticalAlignment="Stretch"
DataContext="{Binding Source={StaticResource vSelectedPort}}"
ItemsSource="{Binding Source={StaticResource vSystemPortsView}}"
SelectedItem="{Binding Source={StaticResource vSelectedPort}, Path=PortName}"
MouseEnter="SystemPortsList_Refresh"
MouseLeave="SystemPortsList_Refresh"
Grid.Row="1"
Grid.Column="1" SelectionChanged="SystemPortsList_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Name="tb" Margin="5,0,0,0" Text="{Binding Path=Name}" />
</StackPanel>
</ListView.ItemTemplate>
</ListView>
I've tried to make an instance of class ComPort for saving current value of selected item from the first ListView, but anyway I can't cope with it without help. How this task should be solved?
1) Instead of handling SelectionChanged on the PortsList ListView, bind your checkbox to the ListViewItemsPanel like so:
<CheckBox IsChecked={Binding IsSelected, RelativeSource=Parent/>
2) Add an x:Name to your first ListBox, say x:Name="ComPortLB";
3) Remove DataContext on SystemPortsList;
4) Fix SelectedItem on SystemPortsList like so:
SelectedValue="{Binding ElementName=ComPortLB, Path=SelectedValue.PortName}"
I haven't tested any of this code and I haven't done this kind of stuff for a while, so I apologize for errors, but it should get you closer. I've also had to make some assumptions about your classes since you don't provide enough information.
I have searched extensively on Google and am struggling to find an easy example to follow for an ItemsControl which I think I need to be able to do the following.
I currently have a Grid with a scrollable Listbox containing Checkboxes which works as expected using the following XAML layout
<Grid>
<ListBox ScrollViewer.VerticalScrollBarVisibility="Auto"
ItemsSource="{Binding Selections}" Margin="12,22,12,94">
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsChecked}"
Content="{Binding Path=Item.SelectionName}">
</CheckBox>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
I now want to add a TextBox to the right of each Checkbox so it's aligned horizontally with 1 Checkbox and 1 Textbox per row. I thought I would have to use an ItemsControl to allow two controls but using the ItemsControl as below I lose the ability to scroll
<Grid>
<ItemsControl ScrollViewer.VerticalScrollBarVisibility="Auto"
ItemsSource="{Binding Selections}" Margin="12,22,12,94">
<ItemsControl.ItemTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsChecked}"
Content="{Binding Path=Item.SelectionName}">
</CheckBox>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
Also, if I try and add a textbox similar to
<DataTemplate>
<CheckBox IsChecked="{Binding sChecked}" Content="{Binding Path=Item.BookieName}" />
<TextBox />
</DataTemplate>
I get an error The object 'DataTemplate' already has a child and cannot add 'TextBox'
Essentially, I want it to look like this
Can anyone give me a few pointers on how to structure the controls in XAML to get my desired layout?
Just use a StackPanel in your DataTemplate and set the orientation to horizontal.
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox IsChecked="{Binding sChecked}" Content="{Binding Path=Item.BookieName}" />
<TextBox />
</StackPanel>
</DataTemplate>
I have a listBox and add data to it like so:
for (int x = 0; x < Orchestrator.Instance.getTopicCount(); x++)
{
listTopics.Items.Add(Orchestrator.Instance.getTopic(x));
}
But I need to be able to do things like have text wrapping and divider lines, so I would like to do it the XAML.
Microsoft shows this:
<TextBlock Width="248" Height="24"
Text="{Binding ElementName=lbColor, Path=SelectedItem.Content,
Mode=OneWay}"
x:Name="tbSelectedColor"
Background="{Binding ElementName=lbColor, Path=SelectedItem.Content,
Mode=OneWay}"/>
But I don't really understand it. Here is my XAML:
<ListBox Height="261" HorizontalAlignment="Left" Margin="352,38,0,0" Name="listContent" VerticalAlignment="Top" Width="391" Grid.Column="1" HorizontalContentAlignment="Left" VerticalContentAlignment="Center" MaxWidth="391" ScrollViewer.HorizontalScrollBarVisibility="Disabled"/>
How am I able to achieve what I want? (Divider lines, text wrapping so I don't have to scroll horizontally, and data binding)
To specify the layout of each item, there are two different things you can change: the ItemContainerStyle, which provides the ControlTemplate used for each ListBoxItem, or the ItemTemplate, which provides the DataTemplate that is used to render each data item. The ItemTemplate is simpler to use if you're just getting started and haven't gotten the hang of ControlTemplates yet.
To get your text to wrap, there are two key things to do. Turn off the default horizontal scrolling of ListBox (which you got already), and set the TextWrapping property of your TextBlock to Wrap. To get to the TextBlock you need to define it in your ItemTemplate. Here's a simple example of the template declared inline, though you could also pull it out as a Resource. For the dividing line I used the simplest approach of a Border with only a bottom black line.
<ListBox x:Name="listContent" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderThickness="0,0,0,1" BorderBrush="Black">
<TextBlock Text="{Binding}" TextWrapping="Wrap"/>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
It seems that you will have to ascend the rather steep learning curve for how to use databinding in WPF first. Thereafter you should learn about DataTemplates and ItemTemplates to get the dividers and so forth.
Try this to get you started
A book I can heartily recommend is WPF in Action from Manning.
You need to define the ItemTemplate of your ListBox.
In your resources, add this:
<DataTemplate x:Key="myItemTemplate" TargetType="ListBoxItem">
<TextBlock Text="{Binding}"/>
</DataTemplate>
Supposing that your getTopic method returns a string, otherwise use {Binding MyTopicProperty} where MyTopicProperty is a property in your Topic class. Customize the TextBlock as you need.
Then use your ListBox like this:
<ListBox ItemTemplate="{StaticResource myItemTemplate"/>
here is an example how to bind listbox with RSS feed with DataTemplate:
<UserControl.Resources>
<XmlDataProvider x:Key ="DataRSS" XPath="//item" Source="http://rss.feedsportal.com/c/629/f/502199/index.rss">< /XmlDataProvider>
</UserControl.Resources>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
<ListBox ItemsSource="{Binding Source={StaticResource DataRSS}}" Height="516" Margin="0,0,32,0" Background="{x:Null}" BorderBrush="#FF627DAE">
<ListBox.ItemTemplate >
<DataTemplate >
<Grid Width="400" Height="100" >
<Image Source="{Binding XPath=enclosure/#url}" Grid.Column="0" HorizontalAlignment="Left" VerticalAlignment="Top" />
<TextBlock TextWrapping="Wrap" Text="{Binding XPath=title}" FontWeight="Bold" Grid.Column="2"/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</grid>