在WPF中将对象绑定到DataTrigger

Question

I am trying create a Grid in my application whenever a Button is pressed.

XAML

<Grid Name="SideBarGrid" HorizontalAlignment="Right">
        <Grid.Style>
            <Style TargetType="Grid">
                <Setter Property="Width" Value="0"/>
                <Style.Triggers>
                    <DataTrigger Binding="What do I put Here?" Value="True"> // HERE
                        <DataTrigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation Duration="0:0:0.1" Storyboard.TargetProperty="Width" To="400" />
                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.EnterActions>
                        <DataTrigger.ExitActions>
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation Duration="0:0:0.1" Storyboard.TargetProperty="Width" To="0" />
                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.ExitActions>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Grid.Style>
    </Grid>

C#

public partial class MoviePanel : Window {
    public MoviePanel() {
        InitializeComponent();
    }
    // List to hold movieDetail objects (each movie is stored with an image and title
    List<MediaDetail> movies = new List<MediaDetail>();       
    MediaDetail selectedMovie;

    private void SelectMovie_Click(object sender, RoutedEventArgs e)
    {
        foreach (MediaDetail media in movies)
        {
            if (media.id == movieID)
            {
                selectedMovie = media;
                selectedMovie.toDisplay = true;
            }
        }
    }

Media Detail

public class MediaDetail
{
    public string id { get; set; }
    public bool toDisplay { get; set; }
}   

I am uncertain as to how I should be binding the selectedMovie object to the DataTrigger . Also should I be declaring a dependency property ?

Answer 1

Your question is unclear on what you're trying to do, you write that you want to bind a DataTrigger to the selectedMovie in one hand and bind to the IsPressed property of a Button on the other hand.

If you want to bind to a button's IsPressed

In this case you won't need a DataTrigger, you'll need a simple Trigger:

<Trigger Property="IsPressed" Value="True" SourceName="YOUR_BUTTON_NAME">
    <!--Your storyboard-->
</Trigger>

A DataTrigger is useful when you want to bind a behavior to a Property in code behind (usually in the ViewModel), what you seems to need here is bind to a DP of another control, a simple Trigger will do that.

Don't forget to name your Button.

If you really want to bind to selectedMovie

Your selectedMovie is not a property, you need one to bind the DataTrigger to it.

private MediaDetail _selectedMovie;
public MediaDetail SelectedMovie {
    get {return _selectedMovie;}
    private set {
        _selectedMovie = value;
        //notifypropertychanged
    }
}

To notify the property changed, you'll need to implement INotifyPropertyChanged. Or turn the SelectedMovie field into a DP.

So your DataTrigger will be:

<DataTrigger Binding="{Binding SelectedMovie, Mode=OneWay}" Value="THE VALUE">

Assuming that the DataContext is your MoviePanel

Don't forget to set the DataContext