CODEWITHSUNDEEP
wpfstylescontroltemplate
Eduardo Brites
Eduardo Brites

Reputation: 4766

How to add a new property to a control template/style

I just created an Expander style with a checkbox in the header:

<Style TargetType="{x:Type Expander}" x:Key="MyCheckboxExpander">
    <Setter Property="Background" Value="{StaticResource ExpanderBackgroundBrush}"/>
    <Setter Property="HeaderTemplate" Value="{StaticResource MyHeaderExpander}" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Expander}">
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="*" x:Name="ContentRow"/>
                    </Grid.RowDefinitions>
                    <Border Grid.Row="0" x:Name="Border" Background="{TemplateBinding Background}" BorderThickness="1" 
                            BorderBrush="{StaticResource ExpanderBorderBrush}" CornerRadius="2,2,0,0">
                        <Grid>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="18"/>
                                <ColumnDefinition Width="*"/>
                                <ColumnDefinition Width="20"/>
                            </Grid.ColumnDefinitions>
                            <CheckBox VerticalAlignment="Center" Margin="4,0,0,2"/>
                            <ToggleButton Grid.Column="2" x:Name="ToggleBt" Template="{DynamicResource MyExpanderToggleButton}" Background="{StaticResource ExpanderBackgroundBrush}" 
                                          IsChecked="{Binding Path=IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" 
                                          OverridesDefaultStyle="True"/>
                            <ContentPresenter Grid.Column="1" Margin="0,0,0,0" RecognizesAccessKey="True" ContentSource="Header"/>
                        </Grid>
                    </Border>
                    <Border Visibility="Collapsed" Grid.Row="1" x:Name="ExpandSite" Background="{StaticResource ContentBackgroundBrush}"
                            BorderBrush="{StaticResource ExpanderBorderBrush}" BorderThickness="1,0,1,1" CornerRadius="0,0,2,2">
                        <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" 
                                          VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Focusable="false"/>
                    </Border>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsExpanded" Value="True">
                        <Setter Property="Visibility" Value="Visible" TargetName="ExpandSite"/>
                    </Trigger>
                    <Trigger Property="IsEnabled" Value="False">
                        <Setter Property="Background" Value="{StaticResource ExpanderBackgroundBrush}" TargetName="Border"/>
                        <Setter Property="BorderBrush" Value="{StaticResource ExpanderBackgroundBrush}" TargetName="Border"/>
                        <Setter Property="Visibility" Value="Hidden" TargetName="ToggleBt" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

How can I create a new property (IsChecked) for this expander in order to bind to a boolean value? e. g:

<Expander IsChecked="{Binding MyBoolValue}" />

Also on the template:

<CheckBox VerticalAlignment="Center" Margin="4,0,0,2" IsChecked="{TemplateBinding ????}" />

EDIT:

I found a similar question but I want to know if there's another way to do it without using control inheritance.

Upvotes: 5

Views: 7039

Answers (1)

Eduardo Brites
Eduardo Brites

Reputation: 4766

I created an Attached Property like this:

public sealed class AP : DependencyObject 
{
    public static bool GetIsChecked(DependencyObject obj)
    {
        return (bool)obj.GetValue(IsCheckedProperty);
    }

    public static void SetIsChecked(DependencyObject obj, bool value)
    {
        obj.SetValue(IsCheckedProperty, value);
    }

    // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty IsCheckedProperty =
        DependencyProperty.RegisterAttached("IsChecked", typeof(bool), typeof(AP), new UIPropertyMetadata(false));
}

Then all I had to do was:

<Expander my:AP.IsChecked="{Binding Path=TestBool}" />

And on the template:

<CheckBox VerticalAlignment="Center" Margin="4,0,0,2" IsChecked="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(my:AP.IsChecked)}" />

I wonder what to do if the style was defined in a different assembly tough...

Upvotes: 4

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