Extensibility & Plugins

Extension Model

An extension is a class implementing ISkiaExtension. It declares an identity and the component types it contributes, then optionally registers them with palette categories and commands:

using Beep.Skia.Extensions;

public sealed class PnIDExtension : ISkiaExtension
{
    public string Id => "com.acme.beep.pnid";
    public string Name => "Piping & Instrumentation";
    public string Version => "1.0.0";
    public string Description => "ISA S5.1 P&ID node family";

    public IEnumerable<Type> GetComponentTypes() => new[]
    {
        typeof(ValveNode),
        typeof(PumpNode),
        typeof(TankNode),
        typeof(PipeNode)
    };

    public void Initialize(ISkiaExtensionContext context)
    {
        context.RegisterComponent(typeof(ValveNode), "P&ID", "Valve");
        context.RegisterComponent(typeof(PumpNode), "P&ID", "Pump");
        context.RegisterCommand("Reverse Flow", component => { /* ... */ });
        context.Log("P&ID extension initialized");
    }
}

Component types must derive from SkiaComponent and expose a public parameterless constructor. The ISkiaExtensionContext surface is deliberately small: RegisterComponent, RegisterCommand and Log. See Extension SDK for the full walkthrough.

SkiaComponentRegistry

SkiaComponentRegistry is the central catalog of component types. It stores discovered AssemblyClassDefinition entries and serves the palette, serialization and instantiation paths:

// Enumerate everything the palette will show
foreach (var def in SkiaComponentRegistry.GetComponentsOrdered())
    Console.WriteLine(def.className);

// Create an instance on demand
var component = SkiaComponentRegistry.CreateComponentInstance("ProcessNode");

if (SkiaComponentRegistry.IsComponentRegistered("ProcessNode"))
    Console.WriteLine("ProcessNode is available");

Extension Host

SkiaExtensionHost discovers and activates extensions. It scans assemblies or a plugin directory, instantiates each ISkiaExtension, calls Initialize with a registration context, and exposes the aggregate surface to the host application:

var host = new SkiaExtensionHost();

// From already-referenced assemblies
int loaded = host.LoadFromAssemblies(new[] { typeof(PnIDExtension).Assembly });

// Or scan a plugin folder
loaded += host.LoadFromDirectory(@"C:\plugins\beep-skia", "*.dll");

// Create a component contributed by an extension
var gauge = host.CreateComponent("Acme.Widgets.CustomGaugeNode, Acme.Widgets");

// Invoke a command registered by an extension
host.InvokeCommand("Reverse Flow", gauge);

ComponentPalette

ComponentPalette is the visual toolbox. It reads the registry, groups components into categories and exposes drag-and-drop events for the host canvas:

1. LoadComponentsFromRegistry() builds the Categories collection from SkiaComponentRegistry.GetComponentsOrdered().
2. Each ComponentCategory exposes its Name, Icon and a collection of ComponentItem entries.
3. Dragging raises ComponentDragStarted, ComponentDragging and ComponentDragEnded with the item and pointer position.
4. The host creates the instance with SkiaComponentRegistry.CreateComponentInstance(), positions it and adds it to the DrawingManager.

var palette = new ComponentPalette { X = 10, Y = 50, Width = 320, Height = 600 };
palette.LoadComponentsFromRegistry();

palette.ComponentDragEnded += (s, args) =>
{
    if (args.State != ComponentDragState.Ended) return;

    var component = SkiaComponentRegistry.CreateComponentInstance(args.Component.ClassDefinition);
    if (component == null) return;

    component.X = args.MousePosition.X;
    component.Y = args.MousePosition.Y;

    drawingManager.AddComponent(component);
    drawingManager.RequestRedraw();
};

drawingManager.AddComponent(palette);

Marketplace & Packages

Extensions are distributed as .beepkg packages and installed through ExtensionPackageManager. The manager validates the package (including archive safety checks), tracks installed versions and exposes the directories that the extension host should scan:

var packages = new ExtensionPackageManager(extensionsRoot);

var result = packages.Install(@"C:\downloads\acme.pnid-1.0.0.beepkg");
if (!result.Success)
    Console.WriteLine(result.Error);

// Load everything that is installed
var host = new SkiaExtensionHost();
foreach (var dir in packages.GetLoadDirectories())
    host.LoadFromDirectory(dir);

For the full packaging format, dependency rules and safety gates, see the Extension Marketplace guide.