Class DirectCanvasRenderer

Namespace

FlowGraph.Avalonia.Rendering

Assembly

FlowGraph.Avalonia.dll

A high-performance graph renderer that draws directly to a DrawingContext, bypassing the Avalonia visual tree for nodes and edges. This is optimized for large graphs (500+ nodes) where per-element Controls are too slow.

Uses GraphRenderModel for all geometry calculations to ensure 100% visual parity with the normal VisualTree renderer.

public class DirectCanvasRenderer : Control, INotifyPropertyChanged, IDataContextProvider, ILogical, IThemeVariantHost, IResourceHost, IResourceNode, IStyleHost, ISetLogicalParent, ISetInheritanceParent, ISupportInitialize, IStyleable, INamed, IInputElement, IDataTemplateHost, ISetterValue, IRenderLayer

Inheritance

object

AvaloniaObject

Animatable

StyledElement

Visual

Layoutable

Interactive

InputElement

Control

DirectCanvasRenderer

Implements

INotifyPropertyChanged

IDataContextProvider

ILogical

IThemeVariantHost

IResourceHost

IResourceNode

IStyleHost

ISetLogicalParent

ISetInheritanceParent

ISupportInitialize

IStyleable

INamed

IInputElement

IDataTemplateHost

ISetterValue

IRenderLayer

Inherited Members

Control.FocusAdornerProperty

Control.TagProperty

Control.ContextMenuProperty

Control.ContextFlyoutProperty

Control.RequestBringIntoViewEvent

Control.ContextRequestedEvent

Control.LoadedEvent

Control.UnloadedEvent

Control.SizeChangedEvent

Control.GetTemplateFocusTarget()

Control.OnLoaded(RoutedEventArgs)

Control.OnUnloaded(RoutedEventArgs)

Control.OnSizeChanged(SizeChangedEventArgs)

Control.OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs)

Control.OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs)

Control.OnGotFocus(GotFocusEventArgs)

Control.OnLostFocus(RoutedEventArgs)

Control.OnCreateAutomationPeer()

Control.OnPointerReleased(PointerReleasedEventArgs)

Control.OnKeyUp(KeyEventArgs)

Control.OnPropertyChanged(AvaloniaPropertyChangedEventArgs)

Control.FocusAdorner

Control.DataTemplates

Control.ContextMenu

Control.ContextFlyout

Control.IsLoaded

Control.Tag

Control.ContextRequested

Control.Loaded

Control.Unloaded

Control.SizeChanged

InputElement.FocusableProperty

InputElement.IsEnabledProperty

InputElement.IsEffectivelyEnabledProperty

InputElement.CursorProperty

InputElement.IsKeyboardFocusWithinProperty

InputElement.IsFocusedProperty

InputElement.IsHitTestVisibleProperty

InputElement.IsPointerOverProperty

InputElement.IsTabStopProperty

InputElement.GotFocusEvent

InputElement.LostFocusEvent

InputElement.KeyDownEvent

InputElement.KeyUpEvent

InputElement.TabIndexProperty

InputElement.TextInputEvent

InputElement.TextInputMethodClientRequestedEvent

InputElement.PointerEnteredEvent

InputElement.PointerExitedEvent

InputElement.PointerMovedEvent

InputElement.PointerPressedEvent

InputElement.PointerReleasedEvent

InputElement.PointerCaptureLostEvent

InputElement.PointerWheelChangedEvent

InputElement.TappedEvent

InputElement.HoldingEvent

InputElement.DoubleTappedEvent

InputElement.Focus(NavigationMethod, KeyModifiers)

InputElement.OnAccessKey(RoutedEventArgs)

InputElement.OnKeyDown(KeyEventArgs)

InputElement.OnTextInput(TextInputEventArgs)

InputElement.OnPointerEntered(PointerEventArgs)

InputElement.OnPointerExited(PointerEventArgs)

InputElement.OnPointerMoved(PointerEventArgs)

InputElement.OnPointerPressed(PointerPressedEventArgs)

InputElement.OnPointerCaptureLost(PointerCaptureLostEventArgs)

InputElement.OnPointerWheelChanged(PointerWheelEventArgs)

InputElement.UpdateIsEffectivelyEnabled()

InputElement.Focusable

InputElement.IsEnabled

InputElement.Cursor

InputElement.IsKeyboardFocusWithin

InputElement.IsFocused

InputElement.IsHitTestVisible

InputElement.IsPointerOver

InputElement.IsTabStop

InputElement.IsEffectivelyEnabled

InputElement.TabIndex

InputElement.KeyBindings

InputElement.IsEnabledCore

InputElement.GestureRecognizers

InputElement.GotFocus

InputElement.LostFocus

InputElement.KeyDown

InputElement.KeyUp

InputElement.TextInput

InputElement.TextInputMethodClientRequested

InputElement.PointerEntered

InputElement.PointerExited

InputElement.PointerMoved

InputElement.PointerPressed

InputElement.PointerReleased

InputElement.PointerCaptureLost

InputElement.PointerWheelChanged

InputElement.Tapped

InputElement.Holding

InputElement.DoubleTapped

Interactive.AddHandler(RoutedEvent, Delegate, RoutingStrategies, bool)

Interactive.AddHandler<TEventArgs>(RoutedEvent<TEventArgs>, EventHandler<TEventArgs>, RoutingStrategies, bool)

Interactive.RemoveHandler(RoutedEvent, Delegate)

Interactive.RemoveHandler<TEventArgs>(RoutedEvent<TEventArgs>, EventHandler<TEventArgs>)

Interactive.RaiseEvent(RoutedEventArgs)

Interactive.BuildEventRoute(RoutedEvent)

Layoutable.DesiredSizeProperty

Layoutable.WidthProperty

Layoutable.HeightProperty

Layoutable.MinWidthProperty

Layoutable.MaxWidthProperty

Layoutable.MinHeightProperty

Layoutable.MaxHeightProperty

Layoutable.MarginProperty

Layoutable.HorizontalAlignmentProperty

Layoutable.VerticalAlignmentProperty

Layoutable.UseLayoutRoundingProperty

Layoutable.UpdateLayout()

Layoutable.ApplyTemplate()

Layoutable.Measure(Size)

Layoutable.Arrange(Rect)

Layoutable.InvalidateMeasure()

Layoutable.InvalidateArrange()

Layoutable.AffectsMeasure<T>(params AvaloniaProperty[])

Layoutable.AffectsArrange<T>(params AvaloniaProperty[])

Layoutable.MeasureCore(Size)

Layoutable.MeasureOverride(Size)

Layoutable.ArrangeCore(Rect)

Layoutable.ArrangeOverride(Size)

Layoutable.OnMeasureInvalidated()

Layoutable.OnVisualParentChanged(Visual, Visual)

Layoutable.Width

Layoutable.Height

Layoutable.MinWidth

Layoutable.MaxWidth

Layoutable.MinHeight

Layoutable.MaxHeight

Layoutable.Margin

Layoutable.HorizontalAlignment

Layoutable.VerticalAlignment

Layoutable.DesiredSize

Layoutable.IsMeasureValid

Layoutable.IsArrangeValid

Layoutable.UseLayoutRounding

Layoutable.EffectiveViewportChanged

Layoutable.LayoutUpdated

Visual.BoundsProperty

Visual.ClipToBoundsProperty

Visual.ClipProperty

Visual.IsVisibleProperty

Visual.OpacityProperty

Visual.OpacityMaskProperty

Visual.EffectProperty

Visual.HasMirrorTransformProperty

Visual.RenderTransformProperty

Visual.RenderTransformOriginProperty

Visual.FlowDirectionProperty

Visual.VisualParentProperty

Visual.ZIndexProperty

Visual.GetFlowDirection(Visual)

Visual.SetFlowDirection(Visual, FlowDirection)

Visual.InvalidateVisual()

Visual.AffectsRender<T>(params AvaloniaProperty[])

Visual.LogicalChildrenCollectionChanged(object, NotifyCollectionChangedEventArgs)

Visual.OnAttachedToVisualTree(VisualTreeAttachmentEventArgs)

Visual.OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs)

Visual.InvalidateMirrorTransform()

Visual.Bounds

Visual.ClipToBounds

Visual.Clip

Visual.IsEffectivelyVisible

Visual.IsVisible

Visual.Opacity

Visual.OpacityMask

Visual.Effect

Visual.HasMirrorTransform

Visual.RenderTransform

Visual.RenderTransformOrigin

Visual.FlowDirection

Visual.ZIndex

Visual.VisualChildren

Visual.VisualRoot

Visual.BypassFlowDirectionPolicies

Visual.AttachedToVisualTree

Visual.DetachedFromVisualTree

StyledElement.DataContextProperty

StyledElement.NameProperty

StyledElement.ParentProperty

StyledElement.TemplatedParentProperty

StyledElement.ThemeProperty

StyledElement.BeginInit()

StyledElement.EndInit()

StyledElement.ApplyStyling()

StyledElement.InitializeIfNeeded()

StyledElement.TryGetResource(object, ThemeVariant, out object)

StyledElement.OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs)

StyledElement.OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs)

StyledElement.OnDataContextChanged(EventArgs)

StyledElement.OnDataContextBeginUpdate()

StyledElement.OnDataContextEndUpdate()

StyledElement.OnInitialized()

StyledElement.Name

StyledElement.Classes

StyledElement.DataContext

StyledElement.IsInitialized

StyledElement.Styles

StyledElement.StyleKey

StyledElement.Resources

StyledElement.TemplatedParent

StyledElement.Theme

StyledElement.LogicalChildren

StyledElement.PseudoClasses

StyledElement.StyleKeyOverride

StyledElement.Parent

StyledElement.ActualThemeVariant

StyledElement.AttachedToLogicalTree

StyledElement.DetachedFromLogicalTree

StyledElement.DataContextChanged

StyledElement.Initialized

StyledElement.ResourcesChanged

StyledElement.ActualThemeVariantChanged

Animatable.TransitionsProperty

Animatable.OnPropertyChangedCore(AvaloniaPropertyChangedEventArgs)

Animatable.Transitions

AvaloniaObject.CheckAccess()

AvaloniaObject.VerifyAccess()

AvaloniaObject.ClearValue(AvaloniaProperty)

AvaloniaObject.ClearValue<T>(AvaloniaProperty<T>)

AvaloniaObject.ClearValue<T>(StyledProperty<T>)

AvaloniaObject.ClearValue<T>(DirectPropertyBase<T>)

AvaloniaObject.Equals(object)

AvaloniaObject.GetHashCode()

AvaloniaObject.GetValue(AvaloniaProperty)

AvaloniaObject.GetValue<T>(StyledProperty<T>)

AvaloniaObject.GetValue<T>(DirectPropertyBase<T>)

AvaloniaObject.GetBaseValue<T>(StyledProperty<T>)

AvaloniaObject.IsAnimating(AvaloniaProperty)

AvaloniaObject.IsSet(AvaloniaProperty)

AvaloniaObject.SetValue(AvaloniaProperty, object, BindingPriority)

AvaloniaObject.SetValue<T>(StyledProperty<T>, T, BindingPriority)

AvaloniaObject.SetValue<T>(DirectPropertyBase<T>, T)

AvaloniaObject.SetCurrentValue(AvaloniaProperty, object)

AvaloniaObject.SetCurrentValue<T>(StyledProperty<T>, T)

AvaloniaObject.Bind(AvaloniaProperty, IBinding)

AvaloniaObject.Bind(AvaloniaProperty, IObservable<object>, BindingPriority)

AvaloniaObject.Bind<T>(StyledProperty<T>, IObservable<object>, BindingPriority)

AvaloniaObject.Bind<T>(StyledProperty<T>, IObservable<T>, BindingPriority)

AvaloniaObject.Bind<T>(StyledProperty<T>, IObservable<BindingValue<T>>, BindingPriority)

AvaloniaObject.Bind<T>(DirectPropertyBase<T>, IObservable<object>)

AvaloniaObject.Bind<T>(DirectPropertyBase<T>, IObservable<T>)

AvaloniaObject.Bind<T>(DirectPropertyBase<T>, IObservable<BindingValue<T>>)

AvaloniaObject.CoerceValue(AvaloniaProperty)

AvaloniaObject.UpdateDataValidation(AvaloniaProperty, BindingValueType, Exception)

AvaloniaObject.RaisePropertyChanged<T>(DirectPropertyBase<T>, T, T)

AvaloniaObject.SetAndRaise<T>(DirectPropertyBase<T>, ref T, T)

AvaloniaObject.InheritanceParent

AvaloniaObject.this[AvaloniaProperty]

AvaloniaObject.this[IndexerDescriptor]

AvaloniaObject.PropertyChanged

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

DirectCanvasRenderer supports custom node rendering via the IDirectNodeRenderer interface. When a node's renderer implements IDirectNodeRenderer, it delegates drawing to that implementation.

Edge endpoint handles are rendered when ShowEdgeEndpointHandles is true and an edge is selected, allowing reconnection/disconnection.

Transform Mode: This renderer uses SelfTransformed mode. It performs its own coordinate transforms internally and MUST be placed in an untransformed container (e.g., RootPanel, not MainCanvas) to avoid double-transformation.

Constructors

DirectCanvasRenderer(FlowCanvasSettings)

Creates a new DirectCanvasRenderer with the specified settings.

public DirectCanvasRenderer(FlowCanvasSettings settings)

Parameters

settings FlowCanvasSettings

Canvas settings for rendering configuration.

DirectCanvasRenderer(FlowCanvasSettings, NodeRendererRegistry?)

Creates a new DirectCanvasRenderer with the specified settings and node renderer registry.

public DirectCanvasRenderer(FlowCanvasSettings settings, NodeRendererRegistry? nodeRenderers)

Parameters

settings FlowCanvasSettings

Canvas settings for rendering configuration.

nodeRenderers NodeRendererRegistry

Optional registry of custom node renderers.

Properties

DisplayName

Display name for debugging and UI purposes.

public string DisplayName { get; }

Property Value

string

EditingEdgeId

Gets the ID of the edge currently being edited, or null if no edge is being edited.

public string? EditingEdgeId { get; }

Property Value

string

EditingNodeId

Gets the ID of the node currently being edited, or null if no node is being edited.

public string? EditingNodeId { get; }

Property Value

string

IsEditing

Gets whether inline editing is currently active.

public bool IsEditing { get; }

Property Value

bool

LayerId

Unique identifier for this layer.

public string LayerId { get; }

Property Value

string

Model

Gets the render model used for geometry calculations. This model is shared with other renderers to ensure visual parity.

public CanvasRenderModel Model { get; }

Property Value

CanvasRenderModel

NodeRenderers

Gets or sets the node renderer registry for custom node types.

public NodeRendererRegistry? NodeRenderers { get; set; }

Property Value

NodeRendererRegistry

TransformMode

How this layer participates in viewport transformations.

public LayerTransformMode TransformMode { get; }

Property Value

LayerTransformMode

Remarks

DirectCanvasRenderer uses SelfTransformed because it performs its own coordinate transforms internally via ScreenToCanvas(double, double). It MUST be placed outside any transformed container (e.g., as a child of RootPanel, not MainCanvas) to avoid double-transformation bugs.

Methods

BeginEditEdge(string)

Begins editing an edge's label. The label will not be drawn while editing.

public void BeginEditEdge(string edgeId)

Parameters

edgeId string

ID of the edge to edit.

BeginEditNode(string)

Begins editing a node's label. The label will not be drawn while editing.

public void BeginEditNode(string nodeId)

Parameters

nodeId string

ID of the node to edit.

ClearHoveredEndpointHandle()

Clears the hovered endpoint handle state.

public void ClearHoveredEndpointHandle()

ClearHoveredPort()

Clears the hovered port state.

public void ClearHoveredPort()

EndEditEdge()

Ends editing an edge's label.

public void EndEditEdge()

EndEditNode()

Ends editing a node's label.

public void EndEditNode()

GetEdgeEndpointViewportPosition(Edge, bool)

Gets the viewport position for an edge endpoint (source or target).

public Point GetEdgeEndpointViewportPosition(Edge edge, bool isSource)

Parameters

edge Edge

isSource bool

Returns

Point

GetPortScreenPosition(Node, Port, bool)

Gets the screen position for a port.

[Obsolete("Use GetPortViewportPosition or GetPortCanvasPosition instead.")]
public Point GetPortScreenPosition(Node node, Port port, bool isOutput)

Parameters

node Node

port Port

isOutput bool

Returns

Point

GetPortViewportPosition(Node, Port, bool)

Gets the viewport position for a port.

public Point GetPortViewportPosition(Node node, Port port, bool isOutput)

Parameters

node Node

port Port

isOutput bool

Returns

Point

Remarks

WARNING: For distance calculations with pointer events, prefer using canvas coordinates (via _model.GetPortPosition) since pointer events give canvas coords via e.GetPosition(MainCanvas).

HitTestEdge(double, double)

Performs hit testing to find an edge at the given screen coordinates.

public Edge? HitTestEdge(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

Edge

The hit edge, or null if no edge was hit.

HitTestEdgeEndpointHandle(double, double)

Performs hit testing to find an edge endpoint handle at the given screen coordinates.

public (Edge edge, bool isSource)? HitTestEdgeEndpointHandle(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

(Edge edge, bool isSource)?

Tuple of (edge, isSource) or null if no handle hit.

HitTestNode(double, double)

Performs hit testing to find a node at the given screen coordinates. Uses quadtree for O(log N) spatial query instead of linear scan.

public Node? HitTestNode(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

Node

The hit node, or null if no node was hit.

HitTestPort(double, double)

Performs hit testing to find a port at the given screen coordinates. Uses quadtree range query for O(log N) spatial lookup.

public (Node node, Port port, bool isOutput)? HitTestPort(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

(Node node, Port port, bool isOutput)?

Tuple of (node, port, isOutput) or null if no port hit.

HitTestResizeHandle(double, double)

Performs hit testing to find a resize handle at the given screen coordinates.

public (Node node, ResizeHandlePosition position)? HitTestResizeHandle(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

(Node node, ResizeHandlePosition position)?

Tuple of (node, position) or null if no handle hit.

HitTestShape(double, double)

Hit tests for shapes at the given screen coordinates. Shapes with higher ZIndex are tested first (topmost shapes have priority).

public ShapeElement? HitTestShape(double screenX, double screenY)

Parameters

screenX double

Screen X coordinate.

screenY double

Screen Y coordinate.

Returns

ShapeElement

The hit shape, or null if no shape was hit.

HitTestShapeResizeHandle(double, double)

Performs hit testing to find a shape resize handle at the given screen coordinates. Shape resize handles are shown when a shape is selected and resizable.

public (ShapeElement shape, ResizeHandlePosition position)? HitTestShapeResizeHandle(double screenX, double screenY)

Parameters

screenX double

X coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

screenY double

Y coordinate relative to the root panel (not canvas). Will be converted internally via ScreenToCanvas.

Returns

(ShapeElement shape, ResizeHandlePosition position)?

Tuple of (shape, position) or null if no handle hit.

InvalidateIndex()

Marks the spatial index as dirty, forcing rebuild on next hit test. Call this when nodes are added, removed, or moved.

public void InvalidateIndex()

InvalidatePositions()

Marks the spatial index as dirty due to node position changes. Unlike InvalidateIndex(), this preserves the node lookup dictionary since the nodes themselves haven't changed, only their positions. Call this during dragging operations for better performance.

public void InvalidatePositions()

Render(DrawingContext)

Renders the visual to a Avalonia.Media.DrawingContext.

public override void Render(DrawingContext context)

Parameters

context DrawingContext

The drawing context.

SetHoveredEndpointHandle(string?, bool)

Sets the currently hovered edge endpoint handle for visual feedback.

public void SetHoveredEndpointHandle(string? edgeId, bool isSource)

Parameters

edgeId string

ID of the edge, or null to clear.

isSource bool

True if hovering the source handle, false for target.

SetHoveredPort(string?, string?)

Sets the currently hovered port for visual feedback.

public void SetHoveredPort(string? nodeId, string? portId)

Parameters

nodeId string

ID of the node containing the port, or null to clear.

portId string

ID of the port, or null to clear.

Update(Graph?, ViewportState, ThemeResources)

Updates the renderer with the current graph state and triggers a redraw.

public void Update(Graph? graph, ViewportState viewport, ThemeResources theme)

Parameters

graph Graph

The graph to render.

viewport ViewportState

Current viewport state for zoom/pan.

theme ThemeResources

Theme resources for styling.

UpdateSettings(FlowCanvasSettings)

Updates the settings and propagates to the render model.

public void UpdateSettings(FlowCanvasSettings settings)

Parameters

settings FlowCanvasSettings

The new settings.