I've got a simple control derived from ContentControl with 3 properties.
My problem comes when I try to perform a control.TransformToVisual() with a control that is placed inside MainContent. It always brings up an ArgumentNullException.
My guess is this due to the control having a null Parent property. Is there a simple way to way around this?
C#
public static readonly DependencyProperty LabelTextProperty =
DependencyProperty.Register("LabelText", typeof(string), typeof(LabelledControl), null);
public static readonly DependencyProperty ValidationContentProperty =
DependencyProperty.Register("ValidationContent", typeof(object), typeof(LabelledControl), null);
public static readonly DependencyProperty MainContentProperty =
DependencyProperty.Register("MainContent", typeof(object), typeof(LabelledControl), null);
XAML
<Style TargetType="local:LabelledControl">
<Setter Property="IsTabStop" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:LabelledControl">
<StackPanel Margin="0 10 0 0">
<StackPanel Orientation="Vertical">
<dataInput:Label Content="{TemplateBinding LabelText}" FontWeight="Bold" FontSize="12" IsTabStop="False"/>
<ContentControl Content="{TemplateBinding ValidationContent}" IsTabStop="False"/>
</StackPanel>
<ContentControl x:Name="_contentControl" Content="{TemplateBinding MainContent}" IsTabStop="False"/>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Have you tried using the ContentPresenter class instead of the ContentControl class within your ControlTemplate to present those properties within the template? I am not sure if it is related to your ArgumentNullException, but typically the content of a ContentControl is exposed on the template via a ContentPresenter.
Since your control derives from ContentControl the ContentPresenter will automatically bind the Content and ContentTemplate properties for you to whatever the Content property is set to. You could also manually bind the Content property of the ContentPresenter to your ValidationContent property.
I am not sure why you are defining a MainContent property when the base ContentControl already gives you a Content property to use, maybe that is a second piece of content you are trying to expose.
Related
I have a custom control, ccTextBlock placed inside a ScrollViewer. The customcontrol will be changing sizes (vertically) when different strings are sent to it through the binding. The custom control will remain on the display, but will change as text elsewhere on the screen is selected.
How can I obtain the actual width and height of the custom control only after and with each text string sent to it? (Using OnApplyTemplate() did not work as it seems to be called only once on the first construction of the custom control.)
Thanks for any replies.
<ScrollViewer VerticalScrollBarVisibility="Auto">
<Grid>
<wc:ccTextBlock Text="{Binding Text, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}" />
</Grid>
</ScrollViewer>
Update: Perhaps a better way to phrase this question would be "How to get the height of an element when it is inside a ScrollViewer". Here is the definition of ccTextBlock:
public class ccTextBlock : Control
{
public string Text
{
get { return (string)GetValue(TextProperty); }
set { SetValue(TextProperty, value); }
}
// Using a DependencyProperty as the backing store for Text. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register("Text", typeof(string), typeof(ccTextBlock), new UIPropertyMetadata(null));
/// <summary>
/// Constructor
/// </summary>
static ccTextBlock()
{
// Initialize as lookless control
DefaultStyleKeyProperty.OverrideMetadata(typeof(ccTextBlock), new FrameworkPropertyMetadata(typeof(ccTextBlock)));
}
public override void OnApplyTemplate()
{
//Effectively apply the template
base.OnApplyTemplate();
Console.WriteLine(String.Format(" ActualHeight is {0}", this.ActualHeight.ToString()));
var x = this.FontSize;
}
}
Where Generic.xaml is:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfCustomControlLibrary">
<Style TargetType="{x:Type local:ccTextBlock}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ccTextBlock}">
<!-- Control Layout -->
<TextBlock Text="{TemplateBinding Text}" TextWrapping="Wrap" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
ActualWidth and ActualHeight are the properties that contain the current width and height of the control.
If you are looking for an Event that notifies about changes, it would be the FrameworkElement.SizeChanged event. You could register for this event in the OnApplyTemplate implementation.
am probably doing something but can't figure out my problem. Any help would be really appreciated:
I am having a CustomControl called Section. A Section is collapsible and therefore its ControlTemplate contains an Expander. The Expanders IsExpanded-Property is bound to the Section's IsExpanded Property via TemplateBinding.
When setting IsExpanded on a Section the Expander collapses, but using the toggleButton within the Expander appears to break that binding. Probably by setting a local value to the Expander's IsExpanded-Property. Anyways, after changing the Expander state via Mouse the binding breaks and setting the Section's IsExpanded doesn't do anything.
This however does not happen when putting an Expander into a view and binding its IsExpanded-Property to some DP in the View.
Also notworthy: Snoop does not show any Bindings on the Expander's IsExpanded-Property. It only shows the Value-Source is ParentTemplate. As soon as I click the ToggleButton to Change IsExpanded the Value-Source changes to Local (possibly breaking the former Binding?)
Section.cs:
public class Section : Control
{
static Section()
{
DefaultStyleKeyProperty.OverrideMetadata(typeof(Section), new FrameworkPropertyMetadata(typeof(Section)));
}
public static readonly DependencyProperty IsExpandedProperty = DependencyProperty.Register(
"IsExpanded", typeof (bool), typeof (Section), new PropertyMetadata(default(bool)));
public bool IsExpanded
{
get { return (bool) GetValue(IsExpandedProperty); }
set { SetValue(IsExpandedProperty, value); }
}
}
Generic.xaml Style:
<Style TargetType="{x:Type local:Section}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:Section}">
<Expander Header="Test" IsExpanded="{TemplateBinding IsExpanded}" >
<Rectangle Fill="Aqua" Height="200" Width="200" />
</Expander>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Any ideas?
So I found the answer which is pretty basic knowledge actually:
TemplateBindings are always ONEWAY no matter what the MetaData states...
Using:
IsExpanded="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsExpanded}"
fixed my problem...
I'm trying to create a style for a textbox which I want to be able to use throughout my code. My style defines a converter in the binding of the Text property but does not set its path because my bound data may not be named the same wherever I use this style.
<Style x:Key="CustomTextBox" BasedOn="{StaticResource {x:Type TextBox}}"
TargetType="{x:Type TextBox}">
<Setter Property="Text">
<Setter.Value>
<Binding>
<Binding.Converter>
<CustomTextBoxConverter/>
</Binding.Converter>
</Binding>
</Setter.Value>
</Setter>
</Style>
And then the customTextBox would be use like so :
<TextBox Height="28" Name="txtRate" Style="{StaticResource CustomTextBox}"
MaxLength="5" Text="{Binding Path=BoundData}"/>
When I write the code above, I get an execption that "Two-way binding requires Path or XPath.".
I even tried to create an attached properties that is used in the style binding to reflect this value in the style but I couldn't get working either. See next :
<Converters:SomeConvertingFunction x:Key="CustomTextConverter"/>
<local:CustomAttachedProperties.ReflectedPath x:Key="ReflectedPath"/>
<Style x:Key="CustomTextBox" BasedOn="{StaticResource {x:Type TextBox}}"
TargetType="{x:Type TextBox}">
<Setter Property="Text">
<Setter.Value>
<Binding Path=ReflectedPath Converter=CustomTextConverter/>
</Setter.Value>
</Setter>
</Style>
Used in a page like so :
<TextBox Height="28" Name="txtRate" Style="{StaticResource CustomTextBox}"
MaxLength="5" CustomAttachedProperty="contextBoundDataAsString"/>
The code for the attached property is :
Public Class CustomAttachedProperties
Public Shared ReadOnly ReflectedPathProperty As DependencyProperty =
DependencyProperty.RegisterAttached("ReflectedPath", GetType(String),
GetType(CustomAttachedProperties))
Public Shared Sub SetReflectedPath(element As UIElement, value As String)
element.SetValue(ReflectedPathProperty, value)
End Sub
Public Shared Function GetReflectedPath(element As UIElement) As String
Return TryCast(element.GetValue(ReflectedPathProperty), String)
End Function
End Class
When I try to using the above code it compiles fine but it does not seem to do anything on my XAML, like it might be creating different instances of the CustomAttachedProperty.
Sorry for the lenghty question but I thought it should be easy to create custom controls that have their own default converters with WPF... I'm confused!
You can create a UserControl that does this quite simply:
<UserControl x:Class="namespace.MyCustomConverterTextBox">
<TextBlock Text="{Binding Text, Converter={StaticResource yourconverter}}"/>
</UserControl>
Then declare Text as a DependencyProperty in code-behind:
public partial class MyCustomConverterTextBox : UserControl
{
public string Text {
get{return (string) GetValue(TextProperty);}
set{SetValue(TextProperty, value);}
}
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register("Text", typeof(string), typeof(MyCustomConverterBox));
}
This should be enough to let you use it in your xaml:
<local:MyCustomConverterTextBox Text="{Binding YourBinding}" />
I didn't run this code so there might be typos, but it should be enough to give you an idea how to go about this.
The best way to do this in my opinion, is to create a new class that inherits from TextBox, then override the PropertyMetadata for the Text property, allowing yourself an opportunity to change the value in a Coerce callback.
I am adding an attached behaviour to a slider which will cause it to scroll some content when the thumb is dragged and held over a specific region. (Can't use a straightforward IsMouseOver trigger as the Slider Thumb has MouseCapture.)
The behaviour has 3 properties:
#region IsScrollHoverProperty
public static readonly DependencyProperty IsScrollHoverProperty = DependencyProperty.RegisterAttached(
"IsScrollHover",
typeof(Boolean),
typeof(ScrollHoverAreaBehaviour),
new UIPropertyMetadata(false));
#endregion
#region ScrollLeftRectProperty
public static readonly DependencyProperty ScrollLeftRectProperty = DependencyProperty.RegisterAttached(
"ScrollLeftRect",
typeof(Rectangle),
typeof(ScrollHoverAreaBehaviour),
new UIPropertyMetadata(null));
#endregion
#region ScrollRightRectProperty
public static readonly DependencyProperty ScrollRightRectProperty = DependencyProperty.RegisterAttached(
"ScrollRightRect",
typeof(Rectangle),
typeof(ScrollHoverAreaBehaviour),
new UIPropertyMetadata(null));
#endregion
The IsScrollHoverProperty is being set to true when the user drags the slider, this is all done in the Slider's ControlTemplates.Triggers, and works correctly.
When it's set to true the callback is going to hook PreviewMouseEnterHandlers into the two Rectangles to detect when the mouse enters them.
The Rectangles in question are also defined in the Slider's controltemplate thusly:
<StackPanel Grid.Row="0" Grid.RowSpan="3" HorizontalAlignment="Left" Orientation="Horizontal">
<Rectangle Width="40" Fill="#AAAAAAAA" Name="ScrollLeftRect"/>
</StackPanel>
<StackPanel Grid.Row="0" Grid.RowSpan="3" HorizontalAlignment="Right" Orientation="Horizontal">
<Rectangle Width="40" Fill="#AAAAAAAA" Name="ScrollRightRect"/>
</StackPanel>
The problem I have is binding these Rectangles to the attached ScrollRightRect and ScrollLeftRect Properties. I have tried a few things and suspect I have made a stupid binding error or am trying to do something not allowed. I am currently binding them in the controltemplate.triggers as follows:
<Trigger Property="local:ScrollHoverAreaBehaviour.IsScrollHover" Value="False">
<Setter Property="local:ScrollHoverAreaBehaviour.ScrollLeftRect" Value="{Binding ElementName=ScrollLeftRect}"/>
<Setter Property="local:ScrollHoverAreaBehaviour.ScrollRightRect" Value="{Binding ElementName=ScrollRightRect}"/>
<Setter TargetName="ScrollLeftRect" Property="Fill" Value="Red"/>
<Setter TargetName="ScrollRightRect" Property="Fill" Value="Red"/>
</Trigger>
I know this Trigger is being tripped as the rectangles fill Red as expected.
Can anyone spot what I'm doing wrong from these snippets?
Thanks in advance.
Rob
First, let's confirm you're not doing anything wrong, and the problem has nothing to do with the attached behaviors.
<Button>
<Button.Template>
<ControlTemplate TargetType="Button">
<Border Background="Yellow">
<StackPanel>
<TextBlock x:Name="theText" Text="Hello" />
<ContentPresenter />
</StackPanel>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Content" Value="{Binding ElementName=theText, Path=Text}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Button.Template>
</Button>
This snippet should cause "Hello" to appear twice when I mouse over the button, but it doesn't, and I get the same error as you:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=theText'. BindingExpression:Path=Text; DataItem=null; target element is 'Button' (Name=''); target property is 'Content' (type 'Object')
This is explainable - once the binding is set on the Button, it won't be able to find a control named 'theText', because the Button lives in a different NameScope.
An alternative
Some WPF controls need to do something similar to you - they assume that a specific control exists in the tree that they will interact with. But they don't use properties - they use names.
Start by giving the controls a name - the convention is to use "PART_" prefix:
<Rectangle ... Name="PART_ScrollLeftRect" />
Now put code like this in your callback when IsScrollHover is set:
private static void IsScrollHoverSetCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var target = (Slider) d;
if ((bool)e.NewValue == false)
return;
target.ApplyTemplate();
var leftRectangle = target.Template.FindName("PART_ScrollLeftRect", target);
var rightRectangle = target.Template.FindName("PART_ScrollRightRect", target);
// Do things with the rectangles
}
Note that depending on when the IsScrollHost property is set, the template might not be ready yet. In that case, you might want to subscribe to the Loaded or similar event, and then call ApplyTemplate().
Although it might seem more complicated, it has one nice benefit: the markup will be simpler. A designer using Blend won't have to remember to wire up those complicated triggers, they just have to name the controls correctly.
The use of the PART_ prefix is a WPF convention, and normally used along with the TemplatePart attribute. An example of this is the TextBox. When you override the template of a TextBox, it won't function until you add a control named PART_ContentHost.
Update: I just blogged about template parts here: http://www.paulstovell.com/wpf-part-names
I have created a custom control for ImageButton as
<Style TargetType="{x:Type Button}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Local:ImageButton}">
<StackPanel Height="Auto" Orientation="Horizontal">
<Image Margin="0,0,3,0" Source="{Binding ImageSource}" />
<TextBlock Text="{TemplateBinding Content}" />
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
ImageButton class looks like
public class ImageButton : Button
{
public ImageButton() : base() { }
public ImageSource ImageSource
{
get { return base.GetValue(ImageSourceProperty) as ImageSource; }
set { base.SetValue(ImageSourceProperty, value); }
}
public static readonly DependencyProperty ImageSourceProperty =
DependencyProperty.Register("Source", typeof(ImageSource), typeof(ImageButton));
}
However I'm not able to bind the ImageSource to the image as:
(This code is in UI Folder and image is in Resource folder)
<Local:ImageButton x:Name="buttonBrowse1" Width="100" Margin="10,0,10,0"
Content="Browse ..." ImageSource="../Resources/BrowseFolder.bmp"/>
But if i take a simple image it gets displayed if same source is specified.
Can anyone tell me what shall be done?
You need to replace the Binding in your ControlTemplate by a TemplateBinding, just as you did for the Content property:
<Image Margin="0,0,3,0" Source="{TemplateBinding ImageSource}" />
Furthermore, the definition of your DependencyProperty is not correct. The string should read ImageSource instead of just Source:
DependencyProperty.Register("ImageSource", typeof(ImageSource), ...
I do not know whether/where this name conflict causes any problems, but at least it is highly recommended to use the exact name of the actual CLR property.
EDIT: You will also have to change the TargetType of your Style to your ImageButton:
<Style TargetType="{x:Type Local:ImageButton}">