Class StdTreeView

Namespace: Alternet.UI

Assembly: Alternet.UI.Common.dll

Displays a hierarchical collection of labeled items with optional images, each represented by a TreeViewItem. This control uses internal VirtualListControl for displaying items, it can be accessed via ListBox property.

[ControlCategory("Common")]
public class StdTreeView : Border, IBaseObjectWithAttr, IBaseObjectWithId, INotifyPropertyChanged, IDisposableObject, IBaseObject, ISupportInitialize, IFocusable, ITextProperty, IComponent, IControl, IDisposable, IWin32Window, ILayoutItem, INotifyDataErrorInfo, ITreeViewItemContainer

Inheritance: object

BaseObject

BaseObjectWithId

BaseObjectWithAttr

BaseObjectWithNotify

DisposableObject

FrameworkElement

AbstractControl

Control

UserControl

Border

StdTreeView

Implements: IBaseObjectWithAttr

IBaseObjectWithId

INotifyPropertyChanged

IDisposableObject

IBaseObject

ISupportInitialize

IFocusable

ITextProperty

IComponent

IControl

IDisposable

IWin32Window

ILayoutItem

INotifyDataErrorInfo

ITreeViewItemContainer

Derived: ActionsListBox

FileListBox

LogListBox

Examples

Here is how to declare a TreeView in UIXML:

<StdTreeView SuggestedWidth="300" SuggestedHeight="240" Name="treeView"
          SelectionChanged="TreeView_SelectionChanged"
          ExpandedChanged="TreeView_ExpandedChanged" />

And the corresponding event handler in the code-behind:

private void TreeView_SelectionChanged(object? sender, EventArgs e)
{
    App.Log($"StdTreeView: SelectionChanged. SelectedItem: {treeView.SelectedItem?.Text}");
}

private void TreeView_ExpandedChanged(object? sender, TreeViewEventArgs e)
{
    App.Log($"StdTreeView: ExpandedChanged. Item: {e.Item.Text} {e.Item.IsExpanded}");
}

Also, a TreeView can be created from code:

static void AddItems(StdTreeView treeView, int count)
{
    var r = new Random();

    int start = treeView.Items.Count + 1;

    treeView.BeginUpdate();
    try
    {
        for (int i = start; i < start + count; i++)
        {
            int imageIndex = r.Next(4);
            var item = new TreeViewItem("Item " + i)
            {
                ImageIndex = imageIndex,
            };
            for (int j = 0; j < 3; j++)
                item.Add(new TreeViewItem(item.Text + "." + j, r.Next(4)));
            treeView.Add(item);
        }
    }
    finally
    {
        treeView.EndUpdate();
    }
}

public Alternet.UI.StdTreeView CreateTreeView()
{
    var result = new Alternet.UI.StdTreeView();
    AddItems(result, 10);
    return result;
}

Constructors

StdTreeView(): Initializes a new instance of the StdTreeView class.

Fields

DefaultLevelMargin: Default margin for each level in the tree.

DefaultTreeButtons: Specifies the default type of buttons used in the tree view control to expand or collapse nodes.

ItemPropertyNamesToRaiseInvalidate: Gets or sets the names of properties of TreeViewItem that should raise an invalidation of the container when changed.

Properties

AllowLabelEdit: Gets a value indicating whether the label text of the tree items can be edited. Default is false. Currently, setter of this property does nothing.

BackgroundColor: Gets or sets the background color for the control.

ContextMenu: Alias for ContextMenuStrip property.

ContextMenuStrip: Gets or sets the ContextMenuStrip associated with this control. This property is auto-created and is always not null. Usage of this property depends on the control.

FirstItem: Gets first root item in the control or null if there are no items.

ForegroundColor: Gets or sets the foreground color for the control.

FullRowSelect: Gets a value indicating whether the selection highlight spans the width of the tree control. Default is true. Currently, setter of this property does nothing.

HasOwnInterior: Gets a value indicating whether the control has internal scroll bars.

Header: Gets the header with columns associated with the control.

ImageList: Gets or sets the ImageList associated with the tree control.

Items: Gets the collection of root items contained within the tree control.

LastItem: Gets last item in the control or null if there are no items.

LastRootItem: Gets last root item in the control or null if there are no items.

ListBox: Gets the underlying VirtualListBox used by this tree control.

RealBackgroundColor: Gets real background color for the control.

RealForegroundColor: Gets real foreground color for the control.

RootItem: Gets or sets the root item of the tree view.

RowLines: Gets a value indicating whether to draw a contrasting border between displayed rows. Default is false. Currently, setter of this property does nothing.

SelectedItem: Gets or sets the selected item in the tree view.

SelectedItems: Gets a collection containing the currently selected items in the control. This is slower than SelectedListItems.

SelectedListItems: Gets a collection containing the currently selected items in the control.

SelectionMode: Gets or sets the selection mode (single or multiple).

ShowExpandButtons: Gets or sets a value indicating whether expand buttons are displayed next to tree items that contain child tree items.

ShowLines: Gets a value indicating whether lines are drawn between tree items in the tree view control. Default is false. Currently, setter of this property does nothing.

ShowRootLines: Gets a value indicating whether lines are drawn between the tree items that are at the root of the tree view. Default is false. Currently, setter of this property does nothing.

TopIndex: Gets or sets the index of the first visible item in the control. Returned value is the index in VisibleItems collection.

TopItem: Gets or sets the first fully-visible tree item in the control. This is slower than TopIndex, so if you have item index, use that instead.

TrackItemPropertyChanges: Gets or sets a value indicating whether to track changes of TreeViewItem properties. Default is true.

TrackItemSelectedChanges: Gets or sets a value indicating whether to track changes of TreeViewItem selection state. Default is true.

TreeButtons: Gets or sets the type of tree view buttons.

TwistButtons: Gets or sets a value indicating whether to select alternative style of +/- buttons and to show rotating ("twisting") arrows instead.

VisibleItems: Gets the collection of visible items contained in the tree view.

Methods

Add(TreeViewItem, bool): Adds the specified item to the tree view on the root level.

Add(string): Adds a new item with the specified title to the tree view on the root level.

AddChild(TreeViewItem?, TreeViewItem, bool): Adds a child item to the specified parent item in the tree view.

AddSeparator(): Adds a separator item to the tree control.

ApplyVisibility(bool, EnumExpandedItemsParams?): Applies a visibility to all items in the tree control, updating their IsVisible property.

ApplyVisibilityFilter(Predicate<TreeViewItem>, EnumExpandedItemsParams?): Applies a visibility filter to items within the tree control, updating their IsVisible property based on a predicate condition.

ApplyVisibilityFilter(string?, StringComparison, EnumExpandedItemsParams?): Applies a visibility filter to items within the tree control, updating their IsVisible property based on a text-matching condition.

BeginUpdate(): Maintains performance while performing slow operations on a control by preventing the control from drawing until the EndUpdate() method is called.

Clear(): Clears all items from the tree view.

ClearSelected(): Unselects all items in the control.

CollapseAll(): Collapses all child tree items.

CreateHeader(): Creates and returns a new instance of a ListBoxHeader.

CreateListBox(): Creates a new instance of the VirtualListBox used by the tree control.

EndUpdate(): Resumes painting the control after painting is suspended by the BeginUpdate() method.

EnsureVisible(TreeViewItem?): Ensures that the tree item is visible, expanding tree items and scrolling the tree view control as necessary.

EnsureVisible(int): Ensures that the child item of the root item with the specified index is visible within the tree view control.

ExpandAll(): Expands all child tree items.

ExpandAllParents(TreeViewItem?): Expands all parent items of the specified item.

GetDefaultParentBackColor(): Gets default value for ParentBackColor property.

GetDefaultParentForeColor(): Gets default value for ParentForeColor property.

GetLevelMargin(): Gets margin for each level in the tree.

GetNodeAt(PointD): Retrieves the tree view item that is at the specified point.

GetNodeAtMouseCursor(): Retrieves the tree control item located at the current mouse cursor position.

InvalidateWhenItemPropertyChanged(TreeViewItem, string?): Determines whether the tree view should be invalidated when a property of an item changes.

ItemContainsText(TreeViewItem?, string?, StringComparison): Gets a value indicating whether the specified item contains the specified substring.

MakeAsListBox(): Changes visual style of the control to look like ListBox.

OnContextMenuCreated(EventArgs): Called when the ContextMenuCreated event is raised.

OnItemPropertyChanged(TreeViewItem, string?): Called when a property of a tree item changes.

OnItemSelectedChanged(TreeViewItem, bool): Called when the selection state of a tree item changes.

OnListBoxAsteriskKeyDown(KeyEventArgs): Handles the behavior when the asterisk (*) key is pressed in the inner list box.

OnListBoxDoubleClick(object?, EventArgs): Handles the double-click event on the inner list box, toggling the expanded state of the selected item while preserving its position and selection.

OnListBoxKeyDown(object?, KeyEventArgs): Handles the KeyDown event for the inner list box.

OnListBoxLeftKeyDown(KeyEventArgs): Handles the behavior when the left arrow key in the inner list box.

OnListBoxMouseDown(object?, MouseEventArgs): Handles the MouseDown event for the inner ListBox.

OnListBoxRightKeyDown(KeyEventArgs): Handles the right arrow key press event for the inner list box, expanding the selected item if it has child items.

OnSystemColorsChanged(EventArgs): Called when the SystemColorsChanged event is raised.

RaiseAfterCollapse(TreeViewItem): Called after the tree item is collapsed.

RaiseAfterExpand(TreeViewItem): Called after the tree item is expanded.

RaiseBeforeCollapse(TreeViewItem, ref bool): Called before the tree item is collapsed.

RaiseBeforeExpand(TreeViewItem, ref bool): Called before the tree item is expanded.

RaiseExpandedChanged(TreeViewItem): Called after 'IsExpanded' property value of a tree item belonging to this tree view changes.

RaiseItemAdded(TreeViewItem): Called when an item is added to this tree view control, at any nesting level.

RaiseItemRemoved(TreeViewItem): Called when an item is removed from this tree view control, at any nesting level.

RefreshTree(): Refreshes the tree view by updating the list of visible items based on the current state of the tree structure.

Remove(TreeViewItem?): Removes the specified item (with sub-items) from the tree view.

RemoveAll(): Removes all items from the tree view control.

RemoveItemAndSelectSibling(TreeViewItem?): Removes item and selects its sibling (next or previous on the same level).

RemoveSelected(): Removes selected items from the control.

RemoveSelectedItem(): Removes the currently selected item from the tree view.

RemoveSelectedItem(bool): Removes the currently selected item from the tree view and optionally selects on of the remaining items.

ResetCachedImagesInItems(): Resets the cached images for all items in the collection.

ScrollIntoView(TreeViewItem?): Scrolls control so the specified item will be fully visible.

SelectFirstItem(): Selects the first item in the tree view control.

SelectFirstItemAndScroll(): Selects the first item in the tree view control and scrolls to it.

SelectItem(TreeViewItem?): Selects the specified item in the tree view and scrolls to it.

SelectLastItem(): Selects the last item in the tree view control.

SelectLastItemAndScroll(): Selects the last item in the tree view control and scrolls to it.

SelectNextTreeButton(): Selects the next type of tree view button.

SetExpandedAndKeepPosAndSelection(TreeViewItem?, bool): Expands or collapses the specified TreeViewItem while preserving the current scroll position and selection.

SetFocus(): Sets input focus to the control.

SetSelected(TreeViewItem, bool): Selects or clears the selection for the specified item.

ToggleExpanded(TreeViewItem?): Toggles the expanded or collapsed state of the specified tree control item.

ToggleExpandedAndCollapseSiblings(TreeViewItem?, bool): Toggles the expanded state of the specified tree item and optionally collapses its sibling items. If collapseSiblings is true and the item has a parent, all sibling items are collapsed before toggling.

ToggleExpandedAndKeepPosAndSelection(TreeViewItem?): Toggles the expanded state of the specified TreeViewItem while preserving the current scroll position and selection.

TreeChanged(): Updates the tree view when the tree structure changes.

Events

AfterCollapse: Occurs after the tree item is collapsed.

AfterExpand: Occurs after the tree item is expanded.

BeforeCollapse: Occurs before the tree item is collapsed. This event can be canceled.

BeforeExpand: Occurs before the tree item is expanded. This event can be canceled.

ExpandedChanged: Occurs after 'IsExpanded' property value of a tree item belonging to this tree view changes.

ItemAdded: Occurs when an item is added to this tree view control, at any nesting level.

ItemPropertyChanged: Occurs when a property of a TreeViewItem changes. This is not fired for all properties of the item.

ItemRemoved: Occurs when an item is removed from this tree view control, at any nesting level.

ItemSelectedChanged: Occurs when the selection state of an item changes.

SelectionChanged: Occurs when the selection has changed.

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