Building a Sample AutoCAD Plugin using C++/CLI for AutoCAD 2025 and later version using .NET 8.0

AutoCADPlugin.cpp

//-----------------------------------------------------------------------------
//----- acrxEntryPoint.cpp
//-----------------------------------------------------------------------------
#include "StdAfx.h"
#include "resource.h"

//-----------------------------------------------------------------------------
#define szRDS _RXST("MAD")

using namespace System;
using namespace System::Windows::Forms;
using namespace System::Threading::Tasks;
using namespace System::Drawing;
using namespace Autodesk::AutoCAD::ApplicationServices::Core;
using namespace Autodesk::AutoCAD::Internal;

// Part 1: AutoCAD Database Helper Class
//----------------------------------------
class AcDbHelper
{
public:
    // Smart pointer for AutoCAD database objects
    template <class T> struct unique_db_ptr : public std::unique_ptr<T, void(*)(AcDbObject*)>
    {
        unique_db_ptr<T>(T* t) : std::unique_ptr<T, void(*)(AcDbObject*)>(t, closeOrDeleteDbObj) { }

        static unique_db_ptr<T> create()
        {
            T* newObj = new T();
            return unique_db_ptr<T>(newObj);
        }
    };

    // Add entity to model space
    static bool addToDb(AcDbEntity* pEnt, AcDbDatabase* pDb = nullptr)
    {
        if (!pDb)
            pDb = acdbHostApplicationServices()->workingDatabase();

        unique_db_ptr<AcDbEntity> ent(pEnt);
        AcDbBlockTable* pBt;
        if (Acad::eOk != pDb->getBlockTable(pBt, AcDb::kForRead))
            return false;

        unique_db_ptr<AcDbBlockTable> bt(pBt);
        AcDbBlockTableRecord* pMs;
        if (Acad::eOk != pBt->getAt(ACDB_MODEL_SPACE, pMs, AcDb::kForWrite))
            return false;

        return Acad::eOk == unique_db_ptr<AcDbBlockTableRecord>(pMs)->appendAcDbEntity(ent.get());
    }

    // Create and add circle to database
    static bool createCircle(const AcGePoint3d& center, double radius, int colorIndex = 1)
    {
        auto circlePtr = unique_db_ptr<AcDbCircle>::create();
        if (!circlePtr)
            return false;

        AcDbCircle* circle = circlePtr.get();
        circle->setDatabaseDefaults();
        circle->setRadius(radius);
        circle->setColorIndex(colorIndex);
        circle->setCenter(center);

        return addToDb(circle);
    }

    // Generate a random color index
    static int getRandomColorIndex()
    {
        int colorArray[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        int index = rand() % 10;
        return (colorArray[index]);
    }

private:
    // Helper function for smart pointer cleanup
    static void closeOrDeleteDbObj(AcDbObject* pObj)
    {
        if (pObj->objectId().isNull())
            delete pObj;
        else
            pObj->close();
    }
};

// Part 2: UI Form Implementation with Clean Design
//----------------------------------------

namespace UIForms {
    namespace AcadApp = Autodesk::AutoCAD::ApplicationServices::Core;
    namespace AcadUtils = Autodesk::AutoCAD::Internal;
    public ref class MainForm : public Form
    {
    private:
        
        // UI Controls
        Button^ drawButton;
        NumericUpDown^ radiusInput;
        Label^ radiusLabel;

        // Initialize the form controls
        void InitializeComponent()
        {
            this->Text = "Advanced AutoCAD Drawing Tool";
            this->Width = 400;
            this->Height = 200;
            this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::FixedDialog;
            this->StartPosition = FormStartPosition::CenterScreen;

            // Radius input setup
            radiusLabel = gcnew Label();
            radiusLabel->Text = "Circle Radius:";
            radiusLabel->Location = Point(50, 40);
            radiusLabel->AutoSize = true;

            radiusInput = gcnew NumericUpDown();
            radiusInput->Location = Point(150, 38);
            radiusInput->Minimum = 1;
            radiusInput->Maximum = 10000;
            radiusInput->Value = 10;
            radiusInput->DecimalPlaces = 2;

            // Draw button setup
            drawButton = gcnew Button();
            drawButton->Text = "Draw Circle";
            drawButton->Location = Point(150, 80);
            drawButton->Width = 100;
            drawButton->Click += gcnew EventHandler(this, &MainForm::DrawButton_Click);

            // Add controls to form
            this->Controls->Add(radiusLabel);
            this->Controls->Add(radiusInput);
            this->Controls->Add(drawButton);
        }
        // Helper method that performs the drawing operation on the main thread
        Task^ DrawCircleAsync(System::Object^ data)
        {
            // Create a TaskCompletionSource to manage the task lifecycle
            auto tcs = gcnew TaskCompletionSource();

            try
            {
                double radius = Convert::ToDouble(radiusInput->Value);
                int colorIndex = AcDbHelper::getRandomColorIndex();
                if (AcDbHelper::createCircle(AcGePoint3d::kOrigin, radius, colorIndex))
                {
                    //Marks the task as successfully completed
                    tcs->SetResult();
                }
                else
                {
                    throw gcnew Exception("Failed to create circle");
                }
            }
            catch (System::Exception^ ex)
            {
                // Marks the task as completed with an exception
                tcs->SetException(ex);
            }

            return tcs->Task;
        }
        /// <summary
        /// Handles the "Draw Circle" button click, initiates the async drawing operation, and handles task completion or errors.
        ///</summary>
        void DrawButton_Click(System::Object^ sender, System::EventArgs^ e)
        {
            // Disable the button to prevent multiple clicks
            drawButton->Enabled = false;

            try
            {
                // Retrieve the DocumentManager to interact with AutoCAD's document system.
                auto dm = Autodesk::AutoCAD::ApplicationServices::Core::Application::DocumentManager;
                // Create a delegate for the DrawCircleAsync method, which returns a Task.
                auto callback = gcnew Func<Object^, Task^>(this, &MainForm::DrawCircleAsync);
                //  Execute the delegate asynchronously within AutoCAD's command context.
                //  This ensures that the drawing operation happens in the correct environment.
                auto task = dm->ExecuteInCommandContextAsync(callback, nullptr);
               //Attach a completion handler(OnCompleted) to the task to handle post - operation actions.
                task->OnCompleted(gcnew Action(this, &MainForm::OnDrawCompleted));
            }
            catch (System::Exception^ ex)
            {
                MessageBox::Show("Error: " + ex->Message, "Error",
                MessageBoxButtons::OK, MessageBoxIcon::Error);
            }
        }
        void OnDrawCompleted()
        {
            try
            {	
                // Enable the button
                drawButton->Enabled = true;
                // Set focus to the drawing area and zoom extents
                AcadUtils::Utils::SetFocusToDwgView();
                AcadUtils::Utils::CancelAndRunCmds("_.zoom\n_extents\n");
            }
            catch (System::Exception^ ex)
            {
                MessageBox::Show("Error: " + ex->Message, "Error",
                MessageBoxButtons::OK, MessageBoxIcon::Error);
            }
        }		
    public:
        MainForm() {
            InitializeComponent();
        }
    };
}



// Part 3: ObjectARX Entry Point
//----------------------------------------
class CArxNetCoreApp : public AcRxArxApp {
public:
    CArxNetCoreApp() : AcRxArxApp() {}

    virtual AcRx::AppRetCode On_kInitAppMsg(void* pkt) {
        return AcRxArxApp::On_kInitAppMsg(pkt);
    }

    virtual AcRx::AppRetCode On_kUnloadAppMsg(void* pkt) {
        return AcRxArxApp::On_kUnloadAppMsg(pkt);
    }

    virtual void RegisterServerComponents() {
    }

    static void MADGUIToolLaunch() {

        UIForms::MainForm^ form = gcnew UIForms::MainForm();
        try
        {
            Autodesk::AutoCAD::ApplicationServices::Application::ShowModelessDialog(form);
        }
        catch (System::Exception^ ex)
        {
            acutPrintf(L"\nException occurred: %s", ex->Message);
        }       
    }   
   
};

IMPLEMENT_ARX_ENTRYPOINT(CArxNetCoreApp)
ACED_ARXCOMMAND_ENTRY_AUTO(CArxNetCoreApp, MADGUI, ToolLaunch, ToolLaunch, ACRX_CMD_MODAL, NULL)