Class TreeVirtualizingCellRendererBase<T>

VirtualizingCellRendererBase is an abstract base class for cell renderers that need live UIElement visuals displayed in a cell. You can derive from this class and provide the type of the UIElement you want to show inside cells as type parameter. The class provides strong typed virtual methods for initializing content of the cell and arranging the cell visuals.

The class manages the creation of cells UIElement objects when the cell is scrolled into view and also unloading of the elements. The class offers an optimization in which elements can be recycled when AllowRecycle is set. In this case when a cell is scrolled out of view it is moved into a recycle bin and the next time a new element is scrolled into view the element is recovered from the recycle bin and reinitialized with the new content of the cell.

Another optimization is support for cells rendering themselves directly to the drawing context. When SupportsRenderOptimization is true the UIElement will only be created when the user moves the mouse over the cell or if the UIElement is needed for other reasons.

After a UIElement was created the virtual methods Syncfusion.Windows.Controls.VirtualTreeView.TreeVirtualizingCellRendererBase`1.WireUIElement(`0) and Syncfusion.Windows.Controls.VirtualTreeView.TreeVirtualizingCellRendererBase`1.UnwireUIElement(`0) are called to wire any event listeners.

Updates to appearance and content of child elements, creation and unloading of elements will not trigger ArrangeOverride or Render calls in parent canvas.

In Grid and Tree control you should not derive from this class. Instead you should derive from the GridVirtualizingCellRendererBase and TreeVirtualizingCellRendererBase classes. These classes are the exact same code base as this class with the only difference that they derive from GridCellRendererBase and TreeCellRenderer base classes instead. It is currently not possible with C# to the base class as template type parameter. This is the reason for this copy/paste approach for the codebase of this class.

Inheritance

System.Object

NonFinalizeDisposable

Disposable

CellRendererBase<TreeRenderStyleInfo>

Syncfusion.Windows.Controls.VirtualTreeView.TreeCellRenderer

TreeVirtualizingCellRendererBase<T>

TreeVirtualizingCellRenderer<T>

Implements

ICellRenderer

System.IDisposable

Inherited Members

CellRendererBase<TreeRenderStyleInfo>.AllowCancelMouseCapture

CellRendererBase<TreeRenderStyleInfo>.Hide(UIElement)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.Arrange(ArrangeCellArgs)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.CancelMouseCapture(UIElement)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.PrepareUIElements(ArrangeCellArgs, List<UIElement>, ScrollControlChildFrame)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.RecaptureMouse(UIElement)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.Render(DrawingContext, RenderCellArgs)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.UnloadUIElements(VirtualizingCellsControl, RowColumnIndex, CellUIElements)

CellRendererBase<TreeRenderStyleInfo>.ICellRenderer.UnloadUIElementsWhenScrolledOutOfView

CellRendererBase<TreeRenderStyleInfo>.isInArrange

CellRendererBase<TreeRenderStyleInfo>.IsInArrange

CellRendererBase<TreeRenderStyleInfo>.OnCancelMouseCapture(UIElement)

CellRendererBase<TreeRenderStyleInfo>.OnRecaptureMouse(UIElement)

CellRendererBase<TreeRenderStyleInfo>.OnRender(DrawingContext, RenderCellArgs, TreeRenderStyleInfo)

CellRendererBase<TreeRenderStyleInfo>.RefreshCellUIElementsContent(VirtualizingCellsControl, CellUIElements, RowColumnIndex)

CellRendererBase<TreeRenderStyleInfo>.UnloadVisualsWhenScrolledOutOfView

Disposable.Finalize()

NonFinalizeDisposable.Dispose()

Namespace: Syncfusion.Windows.Controls.VirtualTreeView

Assembly: Syncfusion.GridCommon.WPF.dll

Syntax

public abstract class TreeVirtualizingCellRendererBase<T> : TreeCellRenderer, ICellRenderer, IDisposable where T : FrameworkElement, new()

Type Parameters

Name	Description
T	The type of the UIElement that should be placed inside cells

Constructors

TreeVirtualizingCellRendererBase()

Declaration

protected TreeVirtualizingCellRendererBase()

Properties

AllowRecycle

Gets or sets a value indicating whether elements can be recycled when scrolled out of view. In this case when a cell is scrolled out of view it is moved into a recycle bin and the next time a new element is scrolled into view the element is recovered from the recycle bin and reinitialized with the new content of the cell. The default value is false.

Declaration

public bool AllowRecycle { get; set; }

Property Value

Type	Description
System.Boolean	true if elements can be recycled when scrolled out of view; otherwise, false.

AllowRecycleIfIsKeyboardFocusWithin

Declaration

public bool AllowRecycleIfIsKeyboardFocusWithin { get; set; }

Property Value

Type
System.Boolean

AllowTransparentBackground

Gets or sets a value indicating whether the background of the UIElement visual placed in the cell can be set to System.Windows.Media.Brushes.Transparent. This is needed in order for the cells control to draw the cell background color behind the UIElement. The default value is true.

Declaration

public bool AllowTransparentBackground { get; set; }

Property Value

Type	Description
System.Boolean	true if [allow transparent background]; otherwise, false.

InInitializeContent

Gets a value indicating whether InitializeContent was called.

Declaration

public bool InInitializeContent { get; }

Property Value

Type	Description
System.Boolean	true if InitializeContent was called; otherwise, false.

SupportsRenderOptimization

Gets or sets whether the renderer supports rendering itsself directly to the drawing context. When this is possible the UIElement will only be created when the user moves the mouse over the cell or if the UIElement is needed for other reasons, e.g. animate after change. The benefit of rendering directly to the DrawingContext instead of creating the UIElement is a much improved scrolling performance. The default value is false.

Declaration

public bool SupportsRenderOptimization { get; set; }

Property Value

Type
System.Boolean

Methods

ArrangeUIElement(ArrangeCellArgs, T, TreeRenderStyleInfo)

Arranges the UI element by setting the Left, Top, Right, Bottom attached properties and its Width, Height, MaxWidth and MaxHeight properties. The visibility is set to Visibility.Visible and the elements Measure and Arrange methods are called.

Declaration

protected virtual void ArrangeUIElement(ArrangeCellArgs aca, T uiElement, TreeRenderStyleInfo style)

Parameters

Type	Name	Description
ArrangeCellArgs	aca	The arrange cell layout.
T	uiElement	The UI element.
TreeRenderStyleInfo	style	The cell style.

CreateUIElement(ArrangeCellArgs, TreeRenderStyleInfo)

Creates a new UIElement of type specified with the class type parameter.

Declaration

protected virtual T CreateUIElement(ArrangeCellArgs aca, TreeRenderStyleInfo cellInfo)

Parameters

Type	Name	Description
ArrangeCellArgs	aca
TreeRenderStyleInfo	cellInfo

Returns

Type
T

Dispose(Boolean)

This gets called when parent grid is unloaded. Unload all elements that were saved for later reuse.

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing

Overrides

NonFinalizeDisposable.Dispose(Boolean)

GetBounds(UIElement)

Declaration

public static Rect GetBounds(UIElement el)

Parameters

Type	Name	Description
System.Windows.UIElement	el

Returns

Type
System.Windows.Rect

GetUIElement(CellUIElements)

Gets the UI element or null if the cell visuals do not have any UIElement visuals.

Declaration

public T GetUIElement(CellUIElements cellUIElements)

Parameters

Type	Name	Description
CellUIElements	cellUIElements	The cell visuals.

Returns

Type
T

InitializeContent(T, TreeRenderStyleInfo)

Called from OnArrange(ArrangeCellArgs, TreeRenderStyleInfo) to initialize the content of the cell using the information from the cell style (value, text, behavior etc.). The method calls the virtual OnInitializeContent(T, TreeRenderStyleInfo) which you should override in your derived class.

Declaration

public void InitializeContent(T uiElement, TreeRenderStyleInfo cellInfo)

Parameters

Type	Name	Description
T	uiElement	The UI element.
TreeRenderStyleInfo	cellInfo	The cell style info.

InitializeDefaultProperties(T)

Set Backgrounds, BorderThickness, Padding and IsEnabled properties.

Declaration

protected virtual void InitializeDefaultProperties(T uiElement)

Parameters

Type	Name	Description
T	uiElement

OnArrange(ArrangeCellArgs, TreeRenderStyleInfo)

Called from Arrange(ArrangeCellArgs) to arrange the cells UIElement children. The method checks ShouldCreateVisuals and if this is true it will initialize the newly created UIElement with attached properties about CellRowColumnIndex, RenderCellInfo, CellRenderer, initialize its default properties with a call to InitializeDefaultProperties(T) and its cell specific content with a call to InitializeContent(T, TreeRenderStyleInfo). The UIElement is arranged on the canvas with a call to ArrangeUIElement(ArrangeCellArgs, T, TreeRenderStyleInfo).

Declaration

protected override void OnArrange(ArrangeCellArgs aca, TreeRenderStyleInfo style)

Parameters

Type	Name	Description
ArrangeCellArgs	aca	The arange cell layout information.
TreeRenderStyleInfo	style	The cell style info.

Overrides

Syncfusion.Windows.Controls.Cells.CellRendererBase<Syncfusion.Windows.Controls.VirtualTreeView.TreeRenderStyleInfo>.OnArrange(Syncfusion.Windows.Controls.Cells.ArrangeCellArgs, Syncfusion.Windows.Controls.VirtualTreeView.TreeRenderStyleInfo)

OnElementArranged(UIElement, Rect)

Declaration

protected virtual void OnElementArranged(UIElement el, Rect rect)

Parameters

Type	Name	Description
System.Windows.UIElement	el
System.Windows.Rect	rect

OnElementMeasured(UIElement, Size)

Declaration

protected virtual void OnElementMeasured(UIElement el, Size size)

Parameters

Type	Name	Description
System.Windows.UIElement	el
System.Windows.Size	size

OnInitializeContent(T, TreeRenderStyleInfo)

Called to initialize the content of the cell using the information from the cell style (value, text, behavior etc.). You must override this method in your derived class.

Declaration

public abstract void OnInitializeContent(T uiElement, TreeRenderStyleInfo cellInfo)

Parameters

Type	Name	Description
T	uiElement	The UI element.
TreeRenderStyleInfo	cellInfo	The cell style info.

OnPrepareUIElements(ArrangeCellArgs, List<UIElement>, ScrollControlChildFrame, TreeRenderStyleInfo)

Called from Arrange(ArrangeCellArgs) to prepare the cells UIElement children. VirtualizingCellRendererBase overrides this method and creates new UIElements and wires them with the parent cells control.

Declaration

protected override void OnPrepareUIElements(ArrangeCellArgs aca, List<UIElement> uiElements, ScrollControlChildFrame canvas, TreeRenderStyleInfo cellInfo)

Parameters

Type	Name	Description
ArrangeCellArgs	aca	The arange cell layout information.
System.Collections.Generic.List<System.Windows.UIElement>	uiElements	The UI elements.
ScrollControlChildFrame	canvas	The canvas to which any UIElement elements should be added.
TreeRenderStyleInfo	cellInfo	The cell style info.

Overrides

Syncfusion.Windows.Controls.Cells.CellRendererBase<Syncfusion.Windows.Controls.VirtualTreeView.TreeRenderStyleInfo>.OnPrepareUIElements(Syncfusion.Windows.Controls.Cells.ArrangeCellArgs, System.Collections.Generic.List<System.Windows.UIElement>, Syncfusion.Windows.Controls.Scroll.ScrollControlChildFrame, Syncfusion.Windows.Controls.VirtualTreeView.TreeRenderStyleInfo)

OnUnloadUIElements(VirtualizingCellsControl, RowColumnIndex, CellUIElements)

Called from UnloadUIElements(VirtualizingCellsControl, RowColumnIndex, CellUIElements) after a cell is scrolled out of view. VirtualizingCellRendererBase overrides this method and creates either removes the cell renderer visuals from the parent canvas or hide them and reuse it later in same canvas depending on whether AllowRecycle was set.

Declaration

protected override sealed void OnUnloadUIElements(VirtualizingCellsControl host, RowColumnIndex cellRowColumnIndex, CellUIElements visuals)

Parameters

Type	Name	Description
VirtualizingCellsControl	host	The host.
RowColumnIndex	cellRowColumnIndex	Index of the cell row column.
CellUIElements	visuals	The visuals.

Overrides

Syncfusion.Windows.Controls.Cells.CellRendererBase<Syncfusion.Windows.Controls.VirtualTreeView.TreeRenderStyleInfo>.OnUnloadUIElements(Syncfusion.Windows.Controls.Cells.VirtualizingCellsControl, Syncfusion.Windows.Controls.Cells.RowColumnIndex, Syncfusion.Windows.Controls.Cells.CellUIElements)

OnUnwireUIElement(T)

Unwire previously wired events from uiElement.

Declaration

protected virtual void OnUnwireUIElement(T uiElement)

Parameters

Type	Name	Description
T	uiElement

OnWireUIElement(T)

Wire events from uiElement

Declaration

protected virtual void OnWireUIElement(T uiElement)

Parameters

Type	Name	Description
T	uiElement

SetBounds(UIElement, Rect)

Helper method which arranges an UI element by setting the Left, Top, Right, Bottom attached properties and its Width, Height, MaxWidth and MaxHeight properties. The visibility is set to Visibility.Visible and the elements Measure and Arrange methods are called.

Declaration

protected void SetBounds(UIElement el, Rect rect)

Parameters

Type	Name	Description
System.Windows.UIElement	el	The element.
System.Windows.Rect	rect	The rectangle.

SetBounds(UIElement, Rect, Boolean, Boolean)

Helper method which arranges an UI element by setting the Left, Top, Right, Bottom attached properties and its Width, Height, MaxWidth and MaxHeight properties. The visibility is set to Visibility.Visible and the elements Measure and Arrange methods are called.

Declaration

protected void SetBounds(UIElement el, Rect rect, bool forceMeasure, bool forceArrange)

Parameters

Type	Name	Description
System.Windows.UIElement	el	The element.
System.Windows.Rect	rect	The rectangle.
System.Boolean	forceMeasure
System.Boolean	forceArrange

Implements

ICellRenderer

System.IDisposable