Class SfTreeView

A SfTreeView class provides a way to display the information in hierarchical structure.

Inheritance

System.Object

SfTreeView

Implements

System.IDisposable

Namespace: Syncfusion.Android.TreeView

Assembly: Syncfusion.SfTreeView.Android.dll

Syntax

public class SfTreeView : FrameLayout, IDisposable, ITreeCollectionView

Examples

This example demonstrates how to initialize SfTreeView in XAML.

<syncfusion:SfTreeView x:Name="treeView"
                       ChildPropertyName="Files"  
                       ItemsSource="{Binding Folders}">
            <syncfusion:SfTreeView.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation = "Horizontal">
                        <ContentPresenter Width="20"
                                          Height="20"
                                          HorizontalAlignment="Stretch"
                                          VerticalAlignment="Center"
                                          ContentTemplate="{Binding ImageTemplate}"/>
                        <TextBlock Margin = "5"
                                   VerticalAlignment="Center"
                                   Text="{Binding FileName}"/>
                    </StackPanel>
                </DataTemplate>
            </syncfusion:SfTreeView.ItemTemplate>
</syncfusion:SfTreeView> 

public class NodeWithImageViewModel
{
   public ObservableCollection<Folder> Folders { get; internal set; }
   private ResourceDictionary CommonResourceDictionary { get; set; }
   public NodeWithImageViewModel()
   {
       CommonResourceDictionary = new ResourceDictionary() { Source = new Uri("ms-appx:///Icons/PathIcon.xaml", UriKind.RelativeOrAbsolute) };
       this.Folders = GetFiles();
   }
   private ObservableCollection<Folder> GetFiles()
   {
       var nodeImageInfo = new ObservableCollection<Folder>();
   var doc = new Folder() { FileName = &quot;Documents&quot;, ImageTemplate = CommonResourceDictionary[&quot;Folder&quot;] as DataTemplate };
   var download = new Folder() { FileName = &quot;Downloads&quot;, ImageTemplate = CommonResourceDictionary[&quot;Folder&quot;] as DataTemplate };

   var pollution = new Folder() { FileName = &quot;Environmental Pollution.docx&quot;, ImageTemplate = CommonResourceDictionary[&quot;Word&quot;] as DataTemplate };
   var globalWarming = new Folder() { FileName = &quot;Global Warming.ppt&quot;, ImageTemplate = CommonResourceDictionary[&quot;PowerPoint&quot;] as DataTemplate };
   var sanitation = new Folder() { FileName = &quot;Sanitation.docx&quot;, ImageTemplate = CommonResourceDictionary[&quot;Word&quot;] as DataTemplate };

   var games = new Folder() { FileName = &quot;Game.exe&quot;, ImageTemplate = CommonResourceDictionary[&quot;EXE&quot;] as DataTemplate };
   var tutorials = new Folder() { FileName = &quot;Tutorials.zip&quot;, ImageTemplate = CommonResourceDictionary[&quot;Zip&quot;] as DataTemplate };


   doc.Files = new ObservableCollection&lt;Folder>
   {
       pollution,
       globalWarming,
       sanitation
   };

   download.Files = new ObservableCollection&lt;Folder>
   {
       games,
       tutorials
   };

   nodeImageInfo.Add(doc);
   nodeImageInfo.Add(download);

   return nodeImageInfo;

}
}
public class Folder : NotificationObject
{
private string fileName;
private DataTemplate imageTemplate;
private ObservableCollection<Folder> files;
public Folder()
{
}
public ObservableCollection<Folder> Files
{
get { return files; }
internal set
{
files = value;
RaisePropertyChanged(nameof(Files));
}
}
public string FileName
{
get { return fileName; }
set
{
fileName = value;
RaisePropertyChanged(nameof(FileName));
}
}
public DataTemplate ImageTemplate
{
get { return imageTemplate; }
set { imageTemplate = value; }
}
}

Constructors

SfTreeView(Context)

Initializes a new instance of the SfTreeView class.

Declaration

public SfTreeView(Context context)

Parameters

Type	Name	Description
Android.Content.Context	context	Represent the Android.Content.Context of SfTreeView.

SfTreeView(Context, IAttributeSet)

Initializes a new instance of the SfTreeView class.

Declaration

public SfTreeView(Context context, IAttributeSet attribute)

Parameters

Type	Name	Description
Android.Content.Context	context	Represent the Android.Content.Context of SfTreeView.
Android.Util.IAttributeSet	attribute	Represent the Android.Util.IAttributeSet of SfTreeView.

SfTreeView(Context, IAttributeSet, Int32)

Initializes a new instance of the SfTreeView class.

Declaration

public SfTreeView(Context context, IAttributeSet attribute, int defaultStyleAttribute)

Parameters

Type	Name	Description
Android.Content.Context	context	Represent the Android.Content.Context of SfTreeView.
Android.Util.IAttributeSet	attribute	Represent the Android.Util.IAttributeSet of SfTreeView.
System.Int32	defaultStyleAttribute	The default style

SfTreeView(Context, IAttributeSet, Int32, Int32)

Initializes a new instance of the SfTreeView class.

Declaration

public SfTreeView(Context context, IAttributeSet attribute, int defaultStyleAttribute, int defaultStyleResource)

Parameters

Type	Name	Description
Android.Content.Context	context	Represent the Android.Content.Context of SfTreeView.
Android.Util.IAttributeSet	attribute	Represent the Android.Util.IAttributeSet of SfTreeView.
System.Int32	defaultStyleAttribute	The default style
System.Int32	defaultStyleResource	The default resource

Properties

Adapter

Gets or sets the TreeViewAdapter to customize the each TreeViewItem's.

Declaration

public TreeViewAdapter Adapter { get; set; }

Property Value

Type
TreeViewAdapter

AutoExpandMode

Gets or sets the value which indicates how the nodes to be expanded while loading.

Declaration

public AutoExpandMode AutoExpandMode { get; set; }

Property Value

Type	Description
AutoExpandMode	The default value is None.

ChildPropertyName

Gets or sets the property name for the child object where ItemsSource is used to define the items for this tree.

Declaration

public string ChildPropertyName { get; set; }

Property Value

Type
System.String

CurrentItem

Gets or sets the current selected item.

Declaration

public object CurrentItem { get; set; }

Property Value

Type	Description
System.Object	The current item.

ExpandActionTarget

Gets or sets a value indicating whether expanding and collapsing of nodes can be performed only by tapping in expander view or in both expander view and content view.

Declaration

public ExpandActionTarget ExpandActionTarget { get; set; }

Property Value

Type
ExpandActionTarget

ExpanderPosition

Gets or sets the expander position in SfTreeView. Default value is Start.

Declaration

public ExpanderPosition ExpanderPosition { get; set; }

Property Value

Type
ExpanderPosition

ExpanderWidth

Gets or sets the width of expander in TreeViewItem.

Declaration

public double ExpanderWidth { get; set; }

Property Value

Type
System.Double

FullRowSelect

Gets or sets a value indicating whether the selection spans the width of tree view control.

Declaration

public bool FullRowSelect { get; set; }

Property Value

Type
System.Boolean

Remarks

Default value false, where the selection start from indent level only.

HierarchyPropertyDescriptors

Gets or sets the list of HierarchyPropertyDescriptors which holds list of HierarchyPropertyDescriptor that provides information of type and property name. TreeView generates the child nodes based ChildPropertyName if the type of data object matches TargetType.

Declaration

public HierarchyPropertyDescriptors HierarchyPropertyDescriptors { get; set; }

Property Value

Type
HierarchyPropertyDescriptors

Indentation

Gets or sets the distance to indent each child TreeViewItem.

Declaration

public double Indentation { get; set; }

Property Value

Type
System.Double

IsAnimationEnabled

Gets or sets a value indicating whether to enable animation while expanding and collapse items.

Declaration

public bool IsAnimationEnabled { get; set; }

Property Value

Type
System.Boolean

IsScrollBarVisible

Gets or sets a value indicating whether to display the scrollbar or not.

Declaration

public bool IsScrollBarVisible { get; set; }

Property Value

Type
System.Boolean

Remarks

ScrollBar cannot be updated at runtime.

Examples

SfTreeView treeView = new SfTreeView();
treeView.IsScrollBarVisible = true;

ItemHeight

Gets or sets the height of each TreeViewItem in SfTreeView.

Declaration

public double ItemHeight { get; set; }

Property Value

Type
System.Double

ItemsSource

Gets or sets the source items to the template and display in SfTreeView.

Declaration

public object ItemsSource { get; set; }

Property Value

Type
System.Object

NodePopulationMode

Gets or sets the value that indicates whether the child nodes should be populated when SfTreeView is loaded or when the node is expanded only.

Declaration

public TreeNodePopulationMode NodePopulationMode { get; set; }

Property Value

Type
TreeNodePopulationMode

Remarks

When NodePopulationMode is OnDemand, the child nodes will be populated when the parent nodes are expanded only. When NodePopulationMode is Instant, all the nodes will be populated when SfTreeView initially loaded. The default value is OnDemand. This property is applicable for Bound mode only.

Nodes

Gets or sets the collection of tree view nodes that are assigned to tree view control in Unbound mode..

Declaration

public TreeViewNodeCollection Nodes { get; set; }

Property Value

Type
TreeViewNodeCollection

NotificationSubscriptionMode

Gets or sets the value that indicates whether to subscribe collection and property changes of data object to perform real time data update. When binding ItemsSource, TreeView subscribes to collection and property changes of data object based on NotificationSubscriptionMode.

Declaration

public NotificationSubscriptionMode NotificationSubscriptionMode { get; set; }

Property Value

Type
NotificationSubscriptionMode

Remarks

When NotificationSubscriptionMode is CollectionChange, TreeView updated its tree structure when child items collection gets changed. When NotificationSubscriptionMode is Property change, TreeView updates its ChildItems when associated collection property gets changed. The default value is None.

Examples

SfTreeView treeView = new SfTreeView();
treeView.NotificationSubscriptionMode = NotificationSubscriptionMode.CollectionChange | NotificationSubscriptionMode.PropertyChange;

SelectedItem

Gets or sets the first selected item.

Declaration

public object SelectedItem { get; set; }

Property Value

Type	Description
System.Object	The selected item.

SelectedItems

Gets or sets the selected items for selection.

Declaration

public ObservableCollection<object> SelectedItems { get; set; }

Property Value

Type
System.Collections.ObjectModel.ObservableCollection<System.Object>

SelectionBackgroundColor

Gets or sets the selection background color for the selected item.

Declaration

public Color SelectionBackgroundColor { get; set; }

Property Value

Type
Android.Graphics.Color

SelectionController

Gets or sets the SelectionController to process and update the selections for TreeViewItem.

Declaration

public SelectionController SelectionController { get; set; }

Property Value

Type
SelectionController

SelectionForegroundColor

Gets or sets the selected item foreground color. Note: It will applicable for unbound mode only.

Declaration

public Color SelectionForegroundColor { get; set; }

Property Value

Type
Android.Graphics.Color

SelectionMode

Gets or sets the selection mode for selection.

Declaration

public SelectionMode SelectionMode { get; set; }

Property Value

Type
SelectionMode

Remarks

By default value, the SelectionMode is SelectionMode.Single.

Methods

BringIntoView(TreeViewNode, Boolean, Boolean, ScrollToPosition)

Attempts to bring the tree view item into view by scrolling.

Declaration

public void BringIntoView(TreeViewNode item, bool disableAnimation = false, bool canExpand = false, ScrollToPosition scrollToPosition)

Parameters

Type	Name	Description
TreeViewNode	item	Represents the TreeViewNode to scroll.
System.Boolean	disableAnimation	true to disable scroll animation while changing the view; otherwise, false. The default is false.
System.Boolean	canExpand	true to expand the collapsed nodes and bring the collapsed node into view; otherwise, false. The default is false.
ScrollToPosition	scrollToPosition	Defines position in the view to which node is scrolled.

Remarks

Need to set NodePopulationMode property to Instant for populating all the nodes to bring the collapsed node into view while calling this method with 'canExpand' parameter as true.

BringIntoView(Object, Boolean, Boolean, ScrollToPosition)

Attempts to bring the TreeViewItem into view by scrolling.

Declaration

public void BringIntoView(object dataObject, bool disableAnimation = false, bool canExpand = false, ScrollToPosition scrollToPosition)

Parameters

Type	Name	Description
System.Object	dataObject	Represents the data object associated with TreeViewNode to scroll.
System.Boolean	disableAnimation	true to disable scroll animation while changing the view; otherwise, false. The default is false.
System.Boolean	canExpand	true to expand the collapsed nodes and bring the collapsed node into view; otherwise, false. The default is false.
ScrollToPosition	scrollToPosition	Defines position in the view to which object is scrolled.

Remarks

Need to set NodePopulationMode property to Instant for populating all the nodes to bring the collapsed node into view while calling this method with 'canExpand' parameter as true.

CollapseAll()

Collapses all the nodes in the SfTreeView.

Declaration

public void CollapseAll()

CollapseNode(TreeViewNode)

Collapses the specified TreeViewNode.

Declaration

public void CollapseNode(TreeViewNode treeViewNode)

Parameters

Type	Name	Description
TreeViewNode	treeViewNode	Specifies the TreeViewNode to collapse it from the view.

CollapseNodes(Int32)

Collapses all the tree view items based on the specified level.

Declaration

public void CollapseNodes(int level = -1)

Parameters

Type	Name	Description
System.Int32	level	Specifies the level of TreeViewNode to collapse all the TreeViewItems from the view.

Dispose(Boolean)

Dispose the instances, if parameter is true.

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing	Represents the boolean value for disposing objects.

ExpandAll()

Expands all the nodes in the SfTreeView.

Declaration

public void ExpandAll()

ExpandNode(TreeViewNode)

Expands the specified TreeViewNode.

Declaration

public void ExpandNode(TreeViewNode treeViewNode)

Parameters

Type	Name	Description
TreeViewNode	treeViewNode	Specifies the TreeViewNode to expand it in the view.

ExpandNodes(Int32)

Expands all the tree view items based on the specified level.

Declaration

public void ExpandNodes(int level = -1)

Parameters

Type	Name	Description
System.Int32	level	Specifies the level of TreeViewNode to expand all the TreeViewItems in the view.

OnAttachedToWindow()

Raises when the SfTreeView is attached into a window.

Declaration

protected override void OnAttachedToWindow()

OnDetachedFromWindow()

Raises when the SfTreeView is detached from a window.

Declaration

protected override void OnDetachedFromWindow()

OnLayout(Boolean, Int32, Int32, Int32, Int32)

Positions and sizes the children of the SfTreeView.

Declaration

protected override void OnLayout(bool changed, int left, int top, int right, int bottom)

Parameters

Type	Name	Description
System.Boolean	changed	Indicates whether the layout has changed or not.
System.Int32	left	The current extreme left position of the SfTreeView.
System.Int32	top	The current top position of the SfTreeView.
System.Int32	right	The current right extreme position of the SfTreeView.
System.Int32	bottom	The current bottom position of the SfTreeView.

OnMeasure(Int32, Int32)

This method is used to get the desired size of an element.

Declaration

protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)

Parameters

Type	Name	Description
System.Int32	widthMeasureSpec	The available width for the element to use.
System.Int32	heightMeasureSpec	The available height for the element to use.

RefreshView()

Refresh the TreeViewItem in UI.

Declaration

public void RefreshView()

ResetTreeViewItems(Object)

Method to reset the visible TreeViewItem’s. If parameter is null, visible tree view items will reset else, particular TreeViewItem will reset.

Declaration

public void ResetTreeViewItems(object data = null)

Parameters

Type	Name	Description
System.Object	data	For Unbound mode, data represents the TreeViewNode and for Bound mode, it represents the data object associated with TreeViewNode.

SelectAll()

Select all the items in the SfTreeView.

Declaration

public void SelectAll()

Events

ItemDoubleTapped

Occurs when the TreeViewItem's ContentView is double tapped.

Declaration

public event EventHandler<ItemDoubleTappedEventArgs> ItemDoubleTapped

Event Type

Type
System.EventHandler<ItemDoubleTappedEventArgs>

ItemHolding

Occurs when the TreeViewItem's ContentView is long pressed.

Declaration

public event EventHandler<ItemHoldingEventArgs> ItemHolding

Event Type

Type
System.EventHandler<ItemHoldingEventArgs>

ItemTapped

Occurs when the TreeViewItem's ContentView is tapped.

Declaration

public event EventHandler<ItemTappedEventArgs> ItemTapped

Event Type

Type
System.EventHandler<ItemTappedEventArgs>

Loaded

Occurs when the SfTreeView is loaded for the first time.

Declaration

public event EventHandler<TreeViewLoadedEventArgs> Loaded

Event Type

Type
System.EventHandler<TreeViewLoadedEventArgs>

LoadOnDemand

Occurs when the TreeViewItem is loaded at run time.

Declaration

public event EventHandler<LoadOnDemandEventArgs> LoadOnDemand

Event Type

Type
System.EventHandler<LoadOnDemandEventArgs>

Examples

SfTreeView treeView = new SfTreeView();
treeView.LoadOnDemand += TreeView_LoadOnDemandEvent;

private async void TreeView_LoadOnDemandEvent(object sender, LoadOnDemandEventArgs e)
{
    if (e.Action == LoadOnDemandAction.RequestStatus)
    {
        ...
        if (!hasChildNodes)
        {
            e.HasChildNodes = false;
            return;
        }
        e.HasChildNodes = true;
    }
    else if(e.Action == Action.PopulateNodes)
    {
        ...
        node.ShowExpanderAnimation = true;
        ...
        node.PopulateChildNodes(items);
        if (items.Count() > 0)
            node.IsExpanded = true;
        node.ShowExpanderAnimation = false;
    }   
}

NodeCollapsed

Occurs when an TreeViewNode is collapsed.

Declaration

public event EventHandler<NodeExpandedCollapsedEventArgs> NodeCollapsed

Event Type

Type
System.EventHandler<NodeExpandedCollapsedEventArgs>

NodeCollapsing

Occurs when an TreeViewNode is being collapsed.

Declaration

public event EventHandler<NodeExpandingCollapsingEventArgs> NodeCollapsing

Event Type

Type
System.EventHandler<NodeExpandingCollapsingEventArgs>

NodeExpanded

Occurs when an TreeViewNode is expanded.

Declaration

public event EventHandler<NodeExpandedCollapsedEventArgs> NodeExpanded

Event Type

Type
System.EventHandler<NodeExpandedCollapsedEventArgs>

NodeExpanding

Occurs when an TreeViewNode is being expanded.

Declaration

public event EventHandler<NodeExpandingCollapsingEventArgs> NodeExpanding

Event Type

Type
System.EventHandler<NodeExpandingCollapsingEventArgs>

QueryNodeSize

Occurs whenever an item comes into view and query the item size.

Declaration

public event EventHandler<QueryNodeSizeEventArgs> QueryNodeSize

Event Type

Type
System.EventHandler<QueryNodeSizeEventArgs>

Remarks

SfTreeView supports auto height feature, by using this event. We can define whether the specified size can be set to the item or not by handling the QueryNodeSize event.

Examples

This example demonstrates how to handle QueryNodeSize event.

using Syncfusion.Android.TreeView;
SfTreeView treeView = new SfTreeView();
treeView.QueryNodeSize += TreeView_QueryNodeSize;
void TreeView_QueryNodeSize (object sender, QueryNodeSizeEventArgs e)
{
e.Height = 40;
e.Handled = true;
}

SelectionChanged

Occurs once the selection process has been completed for the selected item in the SfTreeView.

Declaration

public event EventHandler<ItemSelectionChangedEventArgs> SelectionChanged

Event Type

Type
System.EventHandler<ItemSelectionChangedEventArgs>

SelectionChanging

Occurs while selecting an item's contentview at the execution time.

Declaration

public event EventHandler<ItemSelectionChangingEventArgs> SelectionChanging

Event Type

Type
System.EventHandler<ItemSelectionChangingEventArgs>

Remarks

The SelectionChanging event is a cancelable event and can be canceled by handling the event and setting the Cancel property to true. However, if the event is canceled, the selection process for the selected TreeViewItem's contentview gets cancelled.

Implements

System.IDisposable