Binding custom control property to object trigger

Question

So basically I have a custom WPF control I have made with a property LineType the code for which is here (if needed):

 

public enum LineType
{
    Normal,
    Read,
    Important
}
 
// (the above is in a seperate file)
// -------------------------------------
 
private LineType t = LineType.Normal;
 
public LineType LineType { get { return t; } set { t = value; } }

 

What I am trying to do is have the control have a different background colour depending on the LineType property, even when the controls LineType is changed at run time I would like it to change the background too.

So basically I need to bind the controls property to a Trigger, but it's not working.

This is the code I have at the moment:

 

<UserControl x:Class="WMail.Line"
             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="30" d:DesignWidth="520" MinHeight="30" MinWidth="520" Loaded="UserControl_Loaded">
    <Border x:Name="mb">
        <Grid>
 
        </Grid>
        <Border.Style>
            <Style TargetType="Border">
                <Setter Property="Background" Value="Red" />
                <Style.Triggers>
                    <DataTrigger Binding="{Binding LineType, ElementName=Line}" Value="Normal">
                        <Setter Property="Background" Value="Blue" />
                    </DataTrigger>
                    <DataTrigger Binding="{Binding LineType, ElementName=Line}" Value="Read">
                        <Setter Property="Background" Value="Green" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Border.Style>
    </Border>
</UserControl>

That just stays red though, any help is appreciated thank you :)

EDIT

Been playing around, got this now:

<UserControl x:Class="WMail.Line"
             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="30" d:DesignWidth="520" MinHeight="30" MinWidth="520" Loaded="UserControl_Loaded">
    <UserControl.Resources>
        <Style x:Key="bg" TargetType="{x:Type Border}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=LineType, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" Value="Normal">
                    <Setter Property="Background" Value="Yellow" />
                </DataTrigger>
                <DataTrigger Binding="{Binding Path=LineType, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" Value="Read">
                    <Setter Property="Background" Value="Purple" />
                </DataTrigger>
                <DataTrigger Binding="{Binding Path=LineType, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" Value="Important">
                    <Setter Property="Background" Value="Green" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </UserControl.Resources>
    <Border x:Name="MainB" Style="{DynamicResource bg}">
        <Grid>
            
        </Grid>
    </Border>
</UserControl>

It works fine, but if I change the LineType at run time the colour doesn't change. Any way to fix this?

 

Answer 1

U need to implement INotifyPropertyChanged interface and apply it on ur property..

for example

 private string durationStatus;
        public string DurationStatus
        {
            get { return durationStatus; }
            set 
            {
                durationStatus = value;
                OnPropertyChanged("DurationStatus");
            }
        }

so u need to write OnPropertyChaged("LineType");

now how u can implement this

public partial class Window9 : Window, INotifyPropertyChanged
{
      public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged(string name)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
}

for more information

http://miteshsureja.blogspot.com/2011/07/inotifypropertychanged-interface-in-wpf.html

http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx

---

Thanks, BHavik

Answer 2

Ah thank you, works a charm. Is this way better than a dependency property?