Getting started

An Altium Designer extension is a .NET class library that Altium Designer loads as a server. The server registers commands; menus, toolbars and shortcuts invoke the commands, and each command works with the documents through the SDK interfaces.

Project setup

Create a C# class library and reference the SDK assemblies:

Assembly	Contents
Altium.SDK.Interfaces.dll	The API: interfaces, enumerations and structures (this reference).
Altium.SDK.dll	Hosting classes (DXP.ServerModule, DXP.CommandLauncher), entry points (SCH.GlobalVars, PCB.GlobalVars, DXP.GlobalVars), constants (SCH.SCHConstant) and utilities (DXP.Utils, EDP.Utils).

The current SDK assemblies target .NET 8 (they reference System.Runtime 8.0). Many projects in the SDK examples repository were written for earlier SDK versions and target .NET Framework 4.x; their source code still shows the API usage, but use the target framework that matches your SDK version.

The plugin factory and the server module

Altium Designer creates the extension through a plugin factory. The factory returns a ServerModule subclass, which registers the extension's commands:

using System.Runtime.InteropServices;
using DXP;

namespace MyExtension
{
    public interface IPluginFactory
    {
        object InvokePluginFactory(IClient client);
    }

    [ClassInterface(ClassInterfaceType.None)]
    public class PluginFactory : IPluginFactory
    {
        public object InvokePluginFactory(IClient client) => new PluginServerModule(client, "MyExtension");
    }

    [ClassInterface(ClassInterfaceType.AutoDispatch)]
    public class PluginServerModule : ServerModule
    {
        public PluginServerModule(IClient client, string moduleName) : base(client, moduleName) { }

        protected override void InitializeCommands()
        {
            ((CommandLauncher)CommandLauncher).RegisterCommand("HelloSchematic", Command_HelloSchematic, GetState_HelloSchematic);
        }

        protected override IServerDocument NewDocumentInstance(string kind, string fileName) => null;

        private void Command_HelloSchematic(IServerDocumentView view, ref string parameters)
        {
            // The command's work: see "Working with schematics".
        }

        private void GetState_HelloSchematic(IServerDocumentView context, ref string parameters, ref bool enabled,
            ref bool isChecked, ref bool visible, ref string caption, ref string imageFile)
        {
        }
    }
}

• RegisterCommand binds a command name to two methods: the command itself, and a get state method that Altium Designer calls to decide whether the command is enabled, checked or visible, and with which caption and image.
• NewDocumentInstance is used by extensions that implement a document editor; a command-only extension returns null.

Installation files

Next to the assembly, an extension ships two text files with the extension's name:

• .ins declares the server (its name, the assembly file, version and description) and the commands it provides:

  ClientInsFile 1.0
  
  Server
      EditorName        = 'MyExtension'
      EditorExePath     = 'MyExtension.DLL'
      EditorDescription = 'My first extension'
      Version           = 'Version 1.0.0.1'
  End
  
  Command Name='HelloSchematic' End

• .rcs defines the menus, toolbars and shortcuts that invoke the commands.

The assembly and both files go into a folder under the Altium Designer Extensions folder; Altium Designer loads the extension on start.

Next steps

• API conventions explains how the interfaces are organised.
• Working with schematics completes Command_HelloSchematic.