How to customize TreeView ItemTemplate based on the node in Xamarin.Forms (SfTreeView)

You can customize TextColor and FontSize of SfTreeView node based on the node level using Converters in Xamarin.Forms.

You can also refer the following article.

https://www.syncfusion.com/kb/11393/how-to-customize-treeview-node-based-on-the-node-level-in-xamarin-forms-sftreeview

XAML

Binding the Level property with converters in ItemTemplate.

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:TreeViewXamarin"
             xmlns:syncfusion="clr-namespace:Syncfusion.XForms.TreeView;assembly=Syncfusion.SfTreeView.XForms"
             x:Class="TreeViewXamarin.MainPage">
 
    <ContentPage.BindingContext>
        <local:FileManagerViewModel x:Name="viewModel"/>
    </ContentPage.BindingContext>
 
    <ContentPage.Resources>
        <ResourceDictionary>
            <local:TextColorConverter x:Key="TextColorConverter"/>
            <local:FontSizeConverter x:Key="FontSizeConverter"/>
        </ResourceDictionary>
    </ContentPage.Resources>
 
    <syncfusion:SfTreeView x:Name="treeView" ItemHeight="40" Indentation="15" ExpanderWidth="40" ChildPropertyName="SubFiles" ItemTemplateContextType="Node" 
                           AutoExpandMode="AllNodesExpanded" ItemsSource="{Binding ImageNodeInfo}" VerticalOptions="Center">
        <syncfusion:SfTreeView.ItemTemplate>
            <DataTemplate>
                <Grid x:Name="grid" RowSpacing="0" >
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="1" />
                    </Grid.RowDefinitions>
                    <Grid RowSpacing="0" Grid.Row="0">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="40" />
                            <ColumnDefinition Width="*" />
                        </Grid.ColumnDefinitions>
                        <Grid Padding="5,5,5,5">
                            <Image Source="{Binding Content.ImageIcon}" VerticalOptions="Center" HorizontalOptions="Center" HeightRequest="35" WidthRequest="35"/>
                        </Grid>
                        <Grid Grid.Column="1" VerticalOptions="Center">
                            <Label LineBreakMode="NoWrap" Text="{Binding Content.ItemName}" VerticalTextAlignment="Center"
                                   TextColor="{Binding Level, Converter={x:StaticResource TextColorConverter}}"
                                   FontSize="{Binding Level, Converter={x:StaticResource FontSizeConverter}}">
                            </Label>
                        </Grid>
                    </Grid>
                    <StackLayout Grid.Row="1"/>
                </Grid>
            </DataTemplate>
        </syncfusion:SfTreeView.ItemTemplate>
    </syncfusion:SfTreeView>
 
</ContentPage>

Converter to customize TextColor based on node level.

namespace TreeViewXamarin
{
    public class TextColorConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var level = (int)value;
            if (level == 0)
                return Color.Red;
            else if (level == 1)
                return Color.Blue;
            else
                return Color.Green;
        }
 
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

Converter to customize FontSize based on node level

namespace TreeViewXamarin
{
    public class FontSizeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var level = (int)value;
            if (level == 0)
                return 20;
            else if (level == 1)
                return 17;
            else
                return 14;
        }
 
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

Output

SyncfusionExamples/customize-node-level-treeview-xamarin

How to customize TreeView ItemTemplate based on the node in Xamarin.Forms (SfTreeView)