Nodify

Nodify is a WPF node-based editor control designed to simplify building node-based tools. It is inspired by Unreal Engine's Blueprints but focuses exclusively on the user interface and interaction layer.

Key features include:

• An infinite canvas for placing and moving nodes.
• Support for selecting and dragging groups of nodes.
• Connecting and disconnecting nodes or connectors.
• Zooming and panning capabilities.
• Automatic screen movement when dragging elements near edges.
• High performance optimized for hundreds of nodes.
• Built from the ground up to follow the MVVM (Model-View-ViewModel) pattern.

The CuttingLine control is a custom control designed to remove intersecting connections in a node editor.

Default Gestures

• Start Cutting: SHIFT+ALT+LeftClick (Configurable via EditorGestures.Editor.Cutting).
• Cancel Cutting: Escape key or Right Click (Configurable via EditorGestures.Editor.CancelAction).

Available Commands

You can listen for these commands in NodifyEditor to react to cutting operations:

• CuttingStartedCommand: Fired when the cutting gesture begins.
• CuttingCompletedCommand: Fired when the cutting operation finishes.
• RemoveConnectionCommand: Fired for each intersecting connection when the cutting operation is completed.

The IKeyboardNavigationLayerGroup interface (implemented by NodifyEditor) manages a collection of IKeyboardNavigationLayer objects. It allows you to switch between different layers of keyboard focus, which is useful for navigating between different UI contexts (e.g., moving from a node editor to a property inspector) while maintaining the ability to restore focus to the previously active layer.

Key capabilities include:

• Registering/Removing layers: Adding or removing layers from the group.
• Layer Activation: Explicitly activating a specific layer by its KeyboardNavigationLayerId or cycling through layers using ActivateNextNavigationLayer() and ActivatePreviousNavigationLayer().
• Focus Tracking: Monitoring changes to the active layer via the ActiveNavigationLayerChanged event.

The InputProcessor class in the Nodify.Interactivity namespace is responsible for receiving input events and delegating them to one or more registered IInputHandler instances. It is a central component for managing how user interactions (like mouse or keyboard events) are distributed within the Nodify framework.

To use it, you typically:

1. Instantiate an InputProcessor.
2. Register handlers using AddHandler(IInputHandler).
3. Pass incoming events to the processor via ProcessEvent(InputEventArgs).
4. Monitor the RequiresInputCapture property to determine if the processor needs to maintain focus/capture to continue its current interaction.

The GroupingNode class is a HeaderedContentControl that defines a panel with a header. It is used to group ItemContainers inside it and supports resizing. It provides built-in support for managing the selection of its contained nodes and handling resize lifecycle events.

public class GroupingNode : HeaderedContentControl

Panning allows moving the viewport by holding the right mouse button. You can control panning behavior via the following dependency properties:

• DisablePanning: Set to true to disable manual panning.
• ViewportLocation: Use this to programmatically change the viewport position.
• IsPanning: A read-only property that is true while a panning operation is in progress.
• ViewportSize, ViewportTransform: Updated during panning.

Auto-Panning automatically moves the viewport when selecting or dragging items/connections near the edges.

• DisableAutoPanning: Set to true to disable automatic panning.
• AutoPanSpeed: Controls the speed (default: 10 pixels per tick).
• AutoPanEdgeDistance: Sets the distance from the edge that triggers panning (default: 15 pixels).
• AutoPanningTickRate: The interval for auto-panning updates (default: 1 millisecond).

Nodify uses three distinct layers to manage rendering and interaction, which allows for asynchronous loading of different parts of the graph:

1. Items Layer (NodifyEditor.ItemsSource): Contains the actual content. Each item is wrapped in an ItemContainer to provide selection, dragging, and other interactive capabilities. This layer can render any control, such as a connector or a text block.
2. Connections Layer (NodifyEditor.Connections): Renders all active Connections. By default, this layer is rendered behind the items layer.
3. Decorators Layer (NodifyEditor.Decorators): Manages the positioning and visual decorators for each control within the graph.

The InputGestureRef class is a wrapper for an InputGesture that allows you to change the underlying gesture logic at runtime without changing the reference to the InputGestureRef object itself.

This is particularly useful for components like EditorCommands that capture a reference to a gesture during initialization but need the ability to swap the actual gesture being responded to later.

The Minimap class is a control used to provide a high-level overview of a graph, allowing users to position the viewport and control zoom levels. It inherits from ItemsControl, meaning it can host MinimapItem objects to represent elements of the graph in a scaled-down view.

public class Minimap : ItemsControl