Customizing Leaf Nodes

You can customize leaf nodes by assigning data template to LeafTemplate of SfTreeMap.

Code Sample:

xaml

<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}"> 
   <Grid.DataContext> 
   <local:OlympicMedalsViewModel/>
   </Grid.DataContext> 
   <syncfusion:SfTreeMap ItemsSource="{Binding OlympicMedalsDetails}" Margin="50" WeightValuePath="TotalMedals" ColorValuePath="GoldMedals">
   <syncfusion:SfTreeMap.LeafTemplate> 
   <DataTemplate> 
   <Border BorderBrush="Transparent" BorderThickness="3" Background="#D73028">
   <Image Source="{Binding Data.GameImageSource}" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,25,0,0" Stretch="None"/>
   </Border>
   </DataTemplate>
   </syncfusion:SfTreeMap.LeafTemplate> 
   <syncfusion:SfTreeMap.Levels>
   <syncfusion:TreeMapFlatLevel GroupPath="GameName" ShowLabels="True">
   <syncfusion:TreeMapFlatLevel.LabelTemplate> 
   <DataTemplate>       
   <TextBlock Padding="10 5 0 0" Text="{Binding Label}" FontSize="20" HorizontalAlignment="Left" VerticalAlignment="Top"/> 
   </DataTemplate>         
   </syncfusion:TreeMapFlatLevel.LabelTemplate> 
   </syncfusion:TreeMapFlatLevel>  
   </syncfusion:SfTreeMap.Levels> 
   </syncfusion:SfTreeMap>
</Grid>

c#

public class OlympicMedalsViewModel
    {
		public ObservableCollection<OlympicMedals> OlympicMedalsDetails
		{ get; set; }
        public OlympicMedalsViewModel()
        {        
			this.OlympicMedalsDetails = new ObservableCollection<OlympicMedals>();
			this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Swimming", GoldMedals = 16, SilverMedals = 9, BronzeMedals = 6, TotalMedals = 31, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Swimming.png")) });
            this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Track and Field", GoldMedals = 9, SilverMedals = 13, BronzeMedals = 7, TotalMedals = 29, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/TrackAndField.png")) });
            this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Gymnastics", GoldMedals = 3, SilverMedals = 1, BronzeMedals = 2, TotalMedals = 6, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Gymnastics.png")) });
            this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Cycling", GoldMedals = 1, SilverMedals = 2, BronzeMedals = 1, TotalMedals = 4, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Cycling.png")) });   
			this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Shooting", GoldMedals = 3, SilverMedals = 0, BronzeMedals = 1, TotalMedals = 4, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Shooting.png")) }); 
			this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Wrestling", GoldMedals = 2, SilverMedals = 0, BronzeMedals = 2, TotalMedals = 4, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Wrestling.png")) }); 
			this.OlympicMedalsDetails.Add(new OlympicMedals { Country = "US", GameName = "Diving", GoldMedals = 1, SilverMedals = 1, BronzeMedals = 2, TotalMedals = 4, GameImageSource = new BitmapImage(new Uri("ms-appx:/Assets/Diving.png")) });
		}  
	} 
	public class OlympicMedals
    {
		public string Country { get; set; }
        public string GameName { get; set; } 
		public double GoldMedals { get; set; }
        public double SilverMedals { get; set; }
        public double BronzeMedals { get; set; }
        public double TotalMedals { get; set; }
        public ImageSource GameImageSource { get; set; }
	}