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How to set the ZIndex of the items within the RadTimeLine

Environment

Product RadTimeline for WPF

Description

How to manipulate the ZIndex of items that are shown in the same row in a RadTimeLine.

Solution

Set the Panel.ZIndex attached property of the ContentPresenter elements that hold the TimelineItemControl and TimelineInstantItemControl. To demonstrate this we are going to define a class that will hold sample data.

Example 1: Defining a model

public class TimelineData 
{ 
    public DateTime Date { get; set; } 
    public TimeSpan Time { get; set; } 
    public Brush Background { get; set; } 
    public int ZIndex { get; set; } 
} 
We will also define a custom RowIndexGenerator to show all items in the same row.

Example 2: Defining a RowIndexGenerator

public class RowIndexGenerator : IItemRowIndexGenerator 
{ 
    public void GenerateRowIndexes(List<TimelineRowItem> dataItems) 
    { 
        foreach (var item in dataItems) 
        { 
            item.RowIndex = 0; 
        } 
    } 
} 
The custom logic for setting the Panel.ZIndex to the ZIndex property of the model will be in a separate class.

Example 3: Defining a RowIndexGenerator

public class TimelineUtilities 
{ 
    public static int GetTimelineItemZIndex(DependencyObject obj) 
    { 
        return (int)obj.GetValue(TimelineItemZIndexProperty); 
    } 
 
    public static void SetTimelineItemZIndex(DependencyObject obj, int value) 
    { 
        obj.SetValue(TimelineItemZIndexProperty, value); 
    } 
 
    public static readonly DependencyProperty TimelineItemZIndexProperty = 
        DependencyProperty.RegisterAttached( 
            "TimelineItemZIndex", 
            typeof(int),  
            typeof(TimelineUtilities),  
            new PropertyMetadata(0, OnTimelineItemZIndexChanged)); 
 
    private static void OnTimelineItemZIndexChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
    { 
        var item = (TimelineItemControlBase)d; 
        var presenter = item.ParentOfType<ContentPresenter>(); 
        if (presenter != null) 
        { 
            Panel.SetZIndex(presenter, (int)e.NewValue); 
        } 
    } 
} 
What is left to setup up the code behind and xaml of our MainWindow.

Example 4: Creating a collection of TimelineData objects and setting their ZIndex

public MainWindow() 
{ 
    InitializeComponent(); 
 
    var source = new List<TimelineData>() 
    { 
        new TimelineData() { Date = new DateTime(2020, 1, 20), ZIndex =  2}, 
 
        new TimelineData() { Date = new DateTime(2020, 1, 1), Time = TimeSpan.FromDays(40), ZIndex = 1, Background = Brushes.Yellow }, 
        new TimelineData() { Date = new DateTime(2020, 1, 20), Time = TimeSpan.FromDays(40), Background = Brushes.Blue, 
    }; 
    this.DataContext = source; 
} 
The attached behavior will be added to the items through styles targeting the TimelineItemControl and TimelineInstantItemControl.

Example 5: Defining the RadTimeLine

<telerik:RadTimeline PeriodStart="2020-01-01" 
                        PeriodEnd="2021-01-01" 
                        StartPath="Date" 
                        DurationPath="Time" 
                        ItemsSource="{Binding}"> 
    <telerik:RadTimeline.Resources> 
        <Style TargetType="telerik:TimelineItemControl"> 
            <Setter Property="example:TimelineUtilities.TimelineItemZIndex" Value="{Binding DataItem.ZIndex}" /> 
            <Setter Property="Background" Value="{Binding DataItem.Background}" /> 
        </Style> 
        <Style TargetType="telerik:TimelineInstantItemControl"> 
            <Setter Property="example:TimelineUtilities.TimelineItemZIndex" Value="{Binding DataItem.ZIndex}" /> 
        </Style> 
    </telerik:RadTimeline.Resources> 
    <telerik:RadTimeline.ItemRowIndexGenerator> 
        <example:RowIndexGenerator /> 
    </telerik:RadTimeline.ItemRowIndexGenerator> 
    <telerik:RadTimeline.Intervals> 
        <telerik:DayInterval /> 
        <telerik:WeekInterval /> 
        <telerik:MonthInterval /> 
        <telerik:YearInterval /> 
    </telerik:RadTimeline.Intervals> 
</telerik:RadTimeline> 

Figure 1: Result from Example 5

RadTimeLine items with customized ZIndex

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