In my window I have several generic DataTemplates which use DataTriggers to determine data sources and such. This cuts down heavily on xaml duplication in a window with a lot of similar pages. There are TabControls for navigation, with each TabItem housing a ContentControl using one of said templates.
The exception I'm getting is happening while two TabItems on the same TabControl have the same content. I've isolated the problem at the style for a DevExpress GridControl inside the template. The style has DataTriggers which use the tag of the currently selected TabItem to determine both the ItemsSource and ColumnsSource.
The exception: Name:ChangeLogicalParent MSG:Specified element is already the logical child of another element. Disconnect it first. STACK: at System.Windows.FrameworkContentElement.ChangeLogicalParent(DependencyObject newParent)
Below is an abbreviated version of the xaml:
<DataTemplate x:Key="GridControlTemplate">
...
<dxg:GridControl>
<dxg:GridControl.Style>
<Style TargetType="{x:Type dxg:GridControl}">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TabControl}}, Path=SelectedItem.Tag}"
Value="{StaticResource FirstTag}">
<Setter Property="ColumnsSource" Value="{StaticResource FirstColumns}" />
<Setter Property="ItemsSource" Value="{Binding FirstDataSource}" />
</DataTrigger>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TabControl}}, Path=SelectedItem.Tag}"
Value="{StaticResource SecondTag}">
<Setter Property="ColumnsSource" Value="{StaticResource SecondColumns}" />
<Setter Property="ItemsSource" Value="{Binding SecondDataSource}" />
</DataTrigger>
...
<TabControl>
<TabItem Header="header 1" Tag="{StaticResource FirstTag}">
<ContentControl ContentTemplate="{StaticResource GridControlTemplate}" Content="{Binding}" />
</TabItem>
<TabItem Header="header 2" Tag="{StaticResource SecondTag}">
<ContentControl ContentTemplate="{StaticResource GridControlTemplate}" Content="{Binding}" />
</TabItem>
</TabControl>
Mind you, this works fine for other groups of TabItems sharing identical ContentTemplates. This TabControl scheme works fine when the GridControl's style doesn't have these DataTriggers. With that in mind, might this be a DevExpress-specific issue?
Your GridControl is part of a style held as a static resource. By default resources are shared, that is, the same instance is used by anything that uses the resource. Since both your tabs are using it as their control template, the same GridControl is trying to be made a child of each tab.
You can tell WPF to provide different instances via the x:Shared attribute:
<DataTemplate x:Key="GridControlTemplate" x:Shared="false">
Related
I'm working on a WPF application and i have a little problem.
I have 1 ToggleButton and 1 TextBox. When i click on the ToggleButton, the TextBox apears and gets focus. This is good. But now i want that when i click on another textbox or just somewhere else, that the textbox loses his focus and disapears. I tried this with Differnet triggers and setters, but can't get it to work.
My code now:
<ToggleButton x:Name="SearchButton" Width="100" Height="100" BorderThickness="0" Margin="580,0,0,0" Template="{DynamicResource ButtonBaseControlTemplate1}" Panel.ZIndex="1">
<ToggleButton.Style>
<Style TargetType="ToggleButton">
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsChecked, ElementName=SearchButton}" Value="True" />
<Condition Binding="{Binding Visibility, ElementName=SearchBox}" Value="Visible"/>
</MultiDataTrigger.Conditions>
<Setter Property="FocusManager.FocusedElement" Value="{Binding ElementName=SearchBox}" />
</MultiDataTrigger>
</Style.Triggers>
</Style>
</ToggleButton.Style>
</ToggleButton><TextBox x:Name="SearchBox" Margin="100,33,0,34" Visibility="{Binding IsChecked, ElementName=SearchButton, Converter={StaticResource BoolVisibilityConverter}}" Opacity="0" FontSize="24" FontFamily="Arial" Background="{x:Null}" Foreground="#FF7F7F7F" BorderThickness="0">
<TextBox.Style>
<Style TargetType="TextBox">
<Style.Triggers>
<Trigger Property="TextBox.IsFocused" Value="False">
<Setter Property="ToggleButton.IsChecked" Value="False" TargetName="SearchButton" />
</Trigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
The fact, that the styles in the WPF separated from each other, it's just a bunch of settings setters. We can say, that two different styles for controls, with two different visual trees. So when you're trying to style TextBox to access ToggleButton it does not work, because of its visual tree no ToggleButtons.
In WPF for editing elements in the visual tree, and control in particular, uses a template control or controls placed within view of one Style (but this is usually done with the help of templates, such as DataTemplate, or with ControlTemplate).
I think it will suit you to control the Expander. It already has ToggleButton and content. Example:
XAML
<Expander Header="SearchButton">
<TextBox Text="SearchBox: Opened" Background="Gainsboro" />
</Expander>
Output
To change the view of Expander, you need to change his Style. With it, you can set any form and view of control.
For more information see:
Expander in MSDN
Styling and Templating in MSDN
Customizing the Appearance of an Existing Control by Using a ControlTemplate
Data Templating Overview
I am trying to switch the content of a contentpresenter based on a datatrigger.I want to display a usercontrol in the contentpresenter.content, if i have a value set or else i need to display an error message.But the binding on my datatrigger fails stating that the property is not found.I cant get the datacontext to inherit for the datatrigger checking.I can make it work by using the commented out code.But i am confused why it doesn't work the normal way.
<ContentPresenter.Style>
<Style TargetType="{x:Type ContentPresenter}">
<Setter Property="Content" Value="{Binding UC}"/>
<Style.Triggers>
<!--<DataTrigger Binding="{Binding DataContext.HasValue,RelativeSource={RelativeSource AncestorType={x:Type ContentPresenter}}}" Value="false">
<Setter Property="Content" Value="No preview"/>
</DataTrigger>-->
<DataTrigger Binding="{Binding HasValue}" Value="false">
<Setter Property="Content" Value="No value"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ContentPresenter.Style>
</ContentPresenter>
If you want to use triggers to display UserControl, you should use ContentControl not ContentPresenter.
I prefer to use ContentPresenter for CustomControls and When I am using the UserControl for views of Custom Data Types in my system and Allow to give dynamic behavior.
Example: To switch templates for ContentPresenter you need to set ContentTemplateSelector like this
<ContentPresenter Content="{Binding MyContent}"
ContentTemplate="{Binding MyContentTemplate}"
ContentTemplateSelector="{Binding MyContentTemplateSelector}"/>
MyContent, MyContentTemplate & MyContentTemplateSelector are Dependency Properties and can be binded wherever you are using its instance.
READ :
Usage of ContentPresenter
What is the difference between ContentControl and ContentPresenter
The binding mentioned in the question won't work as
ContentPresenter’s DataContext is automatically set to the value of
its Content property, while ContentControl’s DataContext is not.
Bindings are resolved relatively to the value of the DataContext property. If you declare a binding on the ContentPresenter, the moment its content is set, the binding would be re-evaluated.
ContentControl.Content Property can be changed on any trigger based on your requirement. If you want to use it to change on PropertyChanged Event of a property of ViewModel, DataTrigger can be used by binding it with a DataTemplate with UserControl instance in it or using static resource of that UserControl.
<ContentControl>
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Setter Value="{StaticResource UnSelectedDataTemplate}" Property="ContentTemplate" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsSelected}" Value="True">
<Setter Value="{StaticResource SelectedDataTemplate}" Property="ContentTemplate" />
</DataTrigger>
</Style.Triggers>
</Style>
</ContentContro.Style>
</ContentControl>
READ How to use triggers for content template, more details here
Difference in DataTemplate and StaticResource scope is DataTemplate creates a new instance of the template every time its applied.
Whereas, StaticResource is using the same instance of UserControl again (Static Instance).
You can also use EventTriggers to change content base don Control Events like MouseOver etc.
Alternate approach
Very similar to the above with slight difference. Defining as a data template in resources. Triggering for the content change is essentially identical.
...in <x.Resources /> tag:
<DataTemplate x:Key="DesignerTemplate" DataType="{x:Type vm:SolutionViewModel}">
<vw:SolutionDesignerView />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:SolutionViewModel}">
<ContentControl Content="{Binding }">
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Style.Triggers>
<DataTrigger Binding="{Binding IsLoaded}" Value="True">
<Setter Property="ContentTemplate" Value="{StaticResource DesignerTemplate}" />
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
</DataTemplate>
...then:
<ContentControl Content="{Binding Solution}" />
I usually use trigger Like this...
<UserControl>
<UserControl.Resources>
<DataTemplate x:Key="normalTemplate" >
<!-Fav UserControl->
</DataTemplate >
<DataTemplate x:Key="overWriteTempalte">
<!-Fav UserControl-> </DataTemplate>
</UserControl.Resources>
<ContentPresenter x:Name="ContentField"
Content="{Binding}"
ContentTemplate="{StaticResource ResourceKey=normalTemplate}" />
<UserControl.Triggers>
<DataTrigger Binding="{Binding Path=MyProperty}" Value="True">
<Setter TargetName="ContentField" Property="ContentTemplate" Value="{StaticResource ResourceKey=overWriteTempalte}" />
</DataTrigger>
</UserControl.Triggers>
</UserControl>
If Bindings are a problem Use Snoop to Detect binding errors
I have several StackPanels that change visibility based on ToggleButtons. The code below works if I replace Tag with btn1 on the DataTrigger-lines.
How do I use the value of the Tag property?
<Window x:Class="MyTestApp.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="TestApp">
<Window.Resources>
<Style x:Key="panelStyle" TargetType="{x:Type StackPanel}">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=Tag, Path=IsChecked}" Value="False">
<Setter Property="StackPanel.Visibility" Value="Collapsed" />
</DataTrigger>
<DataTrigger Binding="{Binding ElementName=Tag, Path=IsChecked}" Value="True">
<Setter Property="StackPanel.Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<WrapPanel>
<ToggleButton Content="One" Name="btn1" />
<ToggleButton Content="Two" Name="btn2" />
<StackPanel Style="{StaticResource panelStyle}" Tag="{Binding btn1}">
<Label Content="Data to panel 1" />
</StackPanel>
<StackPanel Style="{StaticResource panelStyle}" Tag="{Binding btn2}">
<Label Content="Data to panel 2" />
</StackPanel>
</WrapPanel>
</Window>
This question is very similar, but I'm missing details on how to pass an element name.
XAML - Generic textbox stylewith triggers / parameters?
Your bindings are incorrect.
In your DataTemplate the bindings should be:
<DataTrigger Binding="{Binding Path=Tag.IsChecked, RelativeSource={RelativeSource Self}}" Value="False">
<Setter Property="StackPanel.Visibility" Value="Collapsed" />
</DataTrigger>
Here the RelativeSource with a mode of Self tells the binding engine that the object to bind against is object to which the style is being applied (e.g. your StackPanel). The PropertyPath of Tag.IsChecked tells the binding engine to look for a property called IsChecked from the object stored in Tag.
Finally the bindings in your StackPanel should be:
<StackPanel Style="{StaticResource panelStyle}" Tag="{Binding ElementName=btn1}">
<Label Content="Data to panel 1" />
</StackPanel>
Here ElementName creates a binding to another element in the logical tree. If you do not explicitly assign to any properties in a Binding as in your original example:
Tag="{Binding btn1}"
The value specified is assigned to the Path property. So this would be the same as:
Tag="{Binding Path=btn1}"
Also note, that using Tag is not considered best practice since it's type is of object and its use is unrestricted, and hence can take on any number of different meanings throughout your project (which often makes it difficult to understand, especially when used in Templates that are located far away from their actual use).
Hope this helps!
Use Converter: set the visibility of StackPanel:
<StackPanel Visivility="{Binding IsChecked, ElementName=btn1, Converter={StaticResource BooleanToVisibilityConverter}}">
...
</StackPanel>
I have 3 different layouts (similar to I guess what you would call Skins but the layouts are hugely different, not just changes to colors and fonts) which I have developed for my application. The layouts are used for displaying the same data, but in a completely different format. Each of these layouts have been constructed within their own Grid.
I want my application to decide which layout to display dynamically based on a string value available at runtime.
What's the best way to get a parent Grid to display a Child Grid dynamically?
I'm trying to find some sort of magical DataTemplate / DataBinding / Templating method but just can't seem to find the best way. Alternatively, should I be looking at a different method of displaying these different layouts? Like an ItemsControl or similar?
Ben
I usually use a ContentControl and DataTrigger to determine what ContentTemplate to use.
For example,
<ContentControl Content="{Binding MyViewModel}">
<ContentControl.Resources>
<DataTemplate x:Key="DefaultTemplate">
<TextBlock Text="DefaultTemplate" />
</DataTemplate>
<DataTemplate x:Key="TemplateA">
<TextBlock Text="Template A" />
</DataTemplate>
<DataTemplate x:Key="TemplateB">
<TextBlock Text="Template B" />
</DataTemplate>
</ContentControl.Resources>
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Setter Property="ContentTemplate" Value="{StaticResource DefaultTemplate}" />
<Style.Triggers>
<DataTrigger Binding="{Binding SelectedView}" Value="ViewA">
<Setter Property="ContentTemplate" Value="{StaticResource TemplateA}" />
</DataTrigger>
<DataTrigger Binding="{Binding SelectedView}" Value="ViewB">
<Setter Property="ContentTemplate" Value="{StaticResource TemplateB}" />
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
In my Silverlight 3 user control I am showing a basic DataGrid control. I need to generate the columns programmatically as follows:
Style headerStyle = (Style)Resources["ColumnHeaderStyle"];
DataGridTextColumn col = new DataGridTextColumn();
col.HeaderStyle = headerStyle;
dataGrid.Columns.Add(col);
The style is defined as follows:
<Style x:Name="ColumnStyle" x:Key="ColumnHeaderStyle"
TargetType="prim:DataGridColumnHeader">
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Loaded="StackPanel_Loaded">
<TextBlock Text="{Binding Name}" />
<TextBlock Text="{Binding Data}" />
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
I want to set the data context of the header to a "header" object (with "Name" and "Data" properties which are referenced in the DataTemplate). Unfortunately, I cannot use the StackPanel_Loaded event as suggested elsewhere, because the event handler is also called when the user starts a column drag&drop operation.
What is the correct way of setting the DataContext of a DataGrid column header?
Here's how you would do it in XAML (this works in WPF; not sure if it works in SL)
<DataGridTextColumn Binding="{Binding Path=Discount}">
<DataGridTextColumn.HeaderStyle>
<Style TargetType="DataGridColumnHeader">
<Setter Property="Content" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=DataContext.DiscountHeader}" />
</Style>
</DataGridTextColumn.HeaderStyle>
</DataGridTextColumn>
Turns out that one can use the Header property (which is of type Object) as the DataContext for the DataTemplate (set as shown above):
Style headerStyle = (Style)Resources["ColumnHeaderStyle"];
DataGridTextColumn col = new DataGridTextColumn();
col.HeaderStyle = headerStyle;
col.Header = myHeaderDataContext; // DataContext for ColumnHeaderStyle
dataGrid.Columns.Add(col);
Based on Matt's answer, I came up with the solution of binding the header on the DataGridCellsPanel which in Snoop appeared to have the correct data context :
<DataGridTemplateColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}" BasedOn="{StaticResource CenterAlignedColumnHeaderStyle}">
<Setter Property="Content" Value="{Binding Path=DataContext.Location, RelativeSource={RelativeSource AncestorType={x:Type DataGridCellsPanel}}}" />
</Style>
</DataGridTemplateColumn.HeaderStyle>
And this is non intrusive in the way that you can still inherits from custom styled headers (see exemple above) or event the base column header style:
<DataGridTemplateColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}" BasedOn="{StaticResource {x:Type DataGridColumnHeader}}">
<Setter Property="Content" Value="{Binding Path=DataContext.Location, RelativeSource={RelativeSource AncestorType={x:Type DataGridCellsPanel}}}" />
</Style>
</DataGridTemplateColumn.HeaderStyle>
This solution has the advantage of being pure and clean XAML and to refer to the closest ancestor holding the correct datacontext rather than trying to reach datacontext of top hierarchy elements like UserControl.