I have a user control with ContentObject property and I use it to specify custom content. On my main window I created a nested label bound to a dependency property. It works fine if I bind it with RelativeSource, but for some reason it doesn't work if I reference element by name:
MainWindow.xaml:
<Window x:Class="TestContentPresenter.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TestContentPresenter"
Title="MainWindow" Height="350" Width="525" Name="MyWindow">
<Grid>
<local:MyUserControl>
<local:MyUserControl.ContentObject>
<!--<TextBlock Text="{Binding MyText, ElementName=MyWindow}"/>-->
<TextBlock Text="{Binding MyText, RelativeSource={RelativeSource AncestorType=Window}}"/>
</local:MyUserControl.ContentObject>
</local:MyUserControl>
</Grid>
</Window>
UserControl.xaml:
<UserControl x:Class="TestContentPresenter.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TestContentPresenter"
Height="300" Width="300" Name="MainControl">
<StackPanel>
<ContentPresenter Content="{Binding ContentObject, ElementName=MainControl}"/>
</StackPanel>
</UserControl>
Main window has MyText dependency property and the commented line is what doesn't work. I suspect that this has something to do with name scopes, but is there anything I'm doing wrong?
No, you are not really doing anything wrong, it's just that the by the time the binding to the TextBlock's Text property gets resolved there is no element named "MyWindow" in scope. You set the ContentObject property of the UserControl to a TextBlock but when the UserControl eventually renders it doesn't know anything about any "MyWindow" name.
You could solve this by simply replacing the ElementName with a RelativeSource - as you have already discovered - since the TextBlock will always have a parent window. ElementName won't work.
Related
I'm using a ContentControl to render various UserControl derivations dynamically. I can't for the life of me figure out how to get the content to stretch when I resize the parent Window. I've found many references like this, but it's still not working for me. Here is a simple example:
This is the Window XAML:
<Window x:Class="WpfApplication3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<ResourceDictionary Source="Dictionary1.xaml"/>
</Window.Resources>
<Grid>
<ContentControl VerticalAlignment="Top"
HorizontalAlignment="Left"
VerticalContentAlignment="Stretch"
HorizontalContentAlignment="Stretch"
Content="{Binding Path=ChildView}"
Margin="10"/>
</Grid>
</Window>
This uses the resource file Dictionary1.XAML:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:viewModels ="clr-namespace:WpfApplication3"
xmlns:views ="clr-namespace:WpfApplication3">
<DataTemplate DataType="{x:Type viewModels:UserControlViewModel}">
<views:UserControl1/>
</DataTemplate>
</ResourceDictionary>
Here is the code behind for the main Window as well as the view model classes:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainViewModel();
}
}
public class MainViewModel
{
public UserControlViewModel ChildView { get; set; }
public MainViewModel()
{
ChildView = new UserControlViewModel();
}
}
public class UserControlViewModel
{
}
and finally the user control:
<UserControl x:Class="WpfApplication3.UserControl1"
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"
mc:Ignorable="d"
Background="Blue"
Height="141" Width="278"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch">
<Grid>
</Grid>
</UserControl>
Here's what it looks like at run time:
What am I missing here? How can I get the child content to behave such that it remains anchored to the top/left of the parent and the bottom/right stretches as the parent is resized?
Two things:
First, you want to remove the VerticalAlignment and HorizontalAlignment on your ContentControl. Setting these will prevent the content control from stretching within its container, so Width and Height are respected, which are both zero by default (so the container has no size on its own).
Setting VerticalAlignment and HorizontalAlignment to Stretch, or leaving it out since it’s the default, will make the container fill the grid, which is what you want.
<ContentControl Content="{Binding Path=ChildView}" Margin="10" />
Second, setting Width and Height within the UserControl will set its size to that fixed size, so it will not adjust itself. Remove those attributes and the user control will default to stretch too, making it fill the content control.
If you want to have a certain size for design purposes, then set the design size instead of the actual control size. For that, you have the d XAML namespace which contains DesignWidth and DesignHeight properties. Setting these will affect the designer but they are ignored later when the view is rendered.
<UserControl x:Class="WpfApplication3.UserControl1"
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" mc:Ignorable="d"
d:DesignWidth="400" d:DesignHeight="250"
Background="Blue">
…
</UserControl>
You set the Height and Width property of the UserControl. This removes any leeway the WPF layouting has. So it does the best thing it can, which is centering the UserControl. If you remove the width and height, it should stretch as you expect.
<UserControl x:Class="WpfApplication3.UserControl1"
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"
mc:Ignorable="d"
Background="Blue"
Height="141" Width="278" //<-- remove
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch">
<Grid>
</Grid>
</UserControl>
As poke kindly reminded me, you also have to remove VerticalAlignment="Top" and HorizontalAlignment="Left"
<ContentControl VerticalAlignment="Top" //<--remove
HorizontalAlignment="Left" //<--remove
VerticalContentAlignment="Stretch"
HorizontalContentAlignment="Stretch"
Content="{Binding Path=ChildView}"
Margin="10"/>
I made a user control
<UserControl x:Class="MyApp.MyControl"
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"
mc:Ignorable="d" x:Name="uc">
<Grid Width="Auto" Height="Auto">
<TextBlock Text="{Binding Path=DataContext.TextContent, ElementName=uc}"/>
<TextBlock Text="{Binding Path=DataContext.TextContent2, ElementName=uc}"/>
</Grid>
I want the sub-controls in the defined control(uc) will bind to the properties of uc.DataContext. I used the defined control as follows:
<Window x:Class="Tms.TMSClient.Views.MainWindow" Name="window"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:control="clr-namespace:MyApp"
xmlns:ribbon="clr-namespace:Microsoft.Windows.Controls.Ribbon;assembly=RibbonControlsLibrary">
<control:MyControl DataContext="{Binding Path=MyControlVM}"/>
The DataContext which is assigned to the window has this structure: WindowVM.MyControlVM.TextContent.
The given code does not work because the textbox's DataContext is bound to WindowVM instead. I think the problem may be because the inner textbox is bound before the defined control (uc) is, thus the bounded DataContext for uc does not take effect yet.
What I want is: the custom control (MyControl) will be bound to its corresponding viewmodel (MyControlVM), and the inner elements of MyControl will be bound to the properties of MyControlVM.
Do you have any solutions for this problem?
If I understand you correctly, you want to data bind a property from your MyControl view model to a TextBox.Text property inside the MyControl UserControl. If that is correct, then you can use a RelativeSource Binding, or the ElementName syntax that you are already using.
First, make sure that your view model is set as the DataContext for the UserControl:
public MyControl()
{
DataContext = new YourControlViewModel();
}
As child controls automatically inherit their parent's DataContext objects, you can now reference this view model from the TextBox through the MyControl.DataContext property from the UserControl's XAML:
<TextBlock Text="{Binding DataContext.TextContent,
RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
That's all you need.
<TextBlock Text="{Binding Path=TextContent}"/>
works for me in my test-application.
MainWindow.xaml
<Window x:Class="DataContextTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="clr-namespace:DataContextTest"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<my:MyOuterDataContext />
</Window.DataContext>
<Grid>
<my:MyControl DataContext="{Binding Path=MyInnerDataContext}" />
</Grid>
MyControl.xaml
<UserControl x:Class="DataContextTest.MyControl"
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"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<TextBlock Text="{Binding Path=TextContent}" />
</Grid>
DataContexts:
public class MyOuterDataContext
{
public MyInnerDataContext MyInnerDataContext { get; set; }
public MyOuterDataContext()
{
MyInnerDataContext = new MyInnerDataContext();
}
}
public class MyInnerDataContext
{
public string TextContent { get { return "foo"; } }
}
By default every control inherits its DataContext from its parent control. Thus there is no need to explicitly bind to it.
Indeed, when you want to bind a control's DataContext to a nested property then you have to specifiy this:
<control:MyControl DataContext="{Binding Path=TextContent}"/>
Why doesn't this binding update?
code:
MainWindow.xaml
<Window x:Class="WpfApplication12.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication12"
Height="350" Width="525">
<StackPanel>
<local:UserControl1 x:Name="usr" />
<TextBlock Text="{Binding ElementName=usr, Path=txt.Text}" />
</StackPanel>
</Window>
UserControl1.xaml
<UserControl x:Class="WpfApplication12.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<TextBox Text="qwe" x:Name="txt" />
</UserControl>
The TextBox inside the UserControl is inaccessible due to its protection level, also it is a field, you can never bind to those. You would need to expose it in the code behind of the UserControl as public property.
public TextBox Txt
{
get { return txt; }
}
Edit: As Henk Holterman pointed out you might not want to expose the whole TextBox, so you could define a dependency property to which the TextBox internally binds for example.
I'm in the process of creating a simple user control; just an ImageButton.
I've already successfully bound the Image to the button and so I've decided to add a tooltip. Now I'm having troubles. It seems that I can hard-code the text for the tooltip in the XAML for the control, but when it's bound it's returning an empty string.
Here's the XAML for my control:
<Button x:Class="BCOCB.DACMS.Controls.ImageButton"
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"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
Name="this"
Style="{StaticResource DisabledButton}">
<Image Source="{Binding ElementName=this, Path=Source}" />
<Button.ToolTip>
<TextBlock Text="{Binding ElementName=this, Path=ToolTipText}" />
</Button.ToolTip>
</Button>
And here's the dependency property info for the tooltip text:
public static readonly DependencyProperty ToolTipTextProperty = DependencyProperty.Register("ToolTipText", typeof(string), typeof(ImageButton));
public string ToolTipText
{
get
{
return this.GetValue(ToolTipTextProperty) as string;
}
set
{
this.SetValue(ToolTipTextProperty, value);
}
}
And, finally, the declaration of the control in my Window:
<controls:ImageButton x:Name="btnAdd" Source="/DACMS;component/Resources/plus.png" ToolTipText="Add New Item" Click="btnAdd_Click" />
As I mentioned before, the image binds just fine and I've done it in exactly the same manner.
Any ideas?
Thanks,
Sonny
EDIT: I have it working now. I've removed the ElementName from the binding and set the TextBlock's DataContext = this in the code behind on instanciation. Still, I'd like to know how to fix this in the XAML, instead.
I'm unable to test this right now, but you can try:
<Button.ToolTip
DataContext=”{Binding Path=PlacementTarget.Parent.Parent,
RelativeSource={x:Static RelativeSource.Self}}"
>
<TextBlock Text="{Binding Path=ToolTipText}" />
</Button.ToolTip>
You may have to experiment a little with the number of "Parent" in PlacementTarget.
Hopefully this works. I don't like giving answers that I haven't tested, but I don't have VS on this computer. :)
I've had this same problem with binding to a ContextMenu. After my research I think that it is because the ToolTip and ContextMenu do not exist within the visual tree of your page/window/control. And therefore the DataContext is not inherited and makes binding troublesome.
Here is a Xaml hack I found that worked for me.
Binding to a MenuItem in a WPF Context Menu
The way to set the data context to "this" through xaml looks like this:
<Control DataContext={Binding RelativeSource={RelativeSource Self}}>
As another point, wpf buttons allow their content to be just about any (single) thing you want. If you want something other than text (ie, text and an image), it looks like this:
<Button Name="SampleButton" Click="SampleButton_Click">
<Grid Width="70" Height="62">
<Label Content="SampleText"/>
<Image Margin="3,3,3,3" Source="Graphics/sample.ico"/>
</Grid>
</Button>
Since you aren't changing anything but the Text on the tooltip TextBlock you can just use an inline declaration which will generate the TextBlock for you and doesn't require any hacking to get around the name scoping issue you're running into otherwise:
<Button ... ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=ToolTipText}">...
You could alternately set the ToolTip on the Image and use the control as the DataContext, which gets around the name scoping problem. The DataContext will be passed to the ToolTip, allowing normal binding:
<Image DataContext="{Binding ElementName=this}" Source="{Binding Source}">
<Image.ToolTip>
<TextBlock FontSize="18" Text="{Binding Path=ToolTipText}" />
</Image.ToolTip>
</Image>
This way allows additional settings on the TextBlock or more complex visuals.
This fixes the Problem with the Tooltip Bindings and Dependencies Properties:
<UserControl x:Class="Extended.InputControls.TextBoxUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Extended.InputControls"
x:Name="UserControl"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<TextBox x:Name="textBox">
<TextBox.ToolTip>
<ToolTip Content="{Binding Path=CustomToolTip}" Background="Yellow"/>
</TextBox.ToolTip>
</TextBox>
</UserControl>
Instead of this ( doesnt Work ):
<UserControl x:Class="Extended.InputControls.TextBoxUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Extended.InputControls"
x:Name="UserControl">
<TextBox x:Name="textBox">
<TextBox.ToolTip>
<ToolTip Content="{Binding ElementName=UserControl, Path=CustomToolTip}" Background="Yellow"/>
</TextBox.ToolTip>
</TextBox>
</UserControl>
I have a window that get its data from another class that is passed as DataContext. But I now also want to do data binding within the window. The window looks as follows:
<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1"
Height="300"
Width="300">
<StackPanel>
<TextBlock Text="{Binding UserName}" />
<TextBlock x:Name="TestTextBlock"
Text="Hello World" />
<TextBlock x:Name="TestTextBlock2"
Text="{Binding ElementName=TestTextBlock,Path=Text}" />
</StackPanel>
</Window>
The binding between the text blocks TestTextBlock and TestTextBlock2 works fine, but only until I change the DataContext-property of the window. How can I bind between those two textblocks so that changing the DataContext will not break the data binding?
Thanks in advance,
Stefan
Try setting the Binding.Mode to OneTime explicitly.
That way, TestTextBlock2.Text will only be set once (if that's what you want).