Création et utilisation d'une DLL sous C++ Builder

13/10/2002

Par LFE (autres articles)
 

Ce document a pour but de présenter la création et l'utilisation d'une DLL suis C++ Builder

//---------------------------------------------------------------------------
#include <vcl.h>
#include <windows.h>
#pragma hdrstop

//---------------------------------------------------------------------------
// Important note ... bla bla ...
//---------------------------------------------------------------------------
#pragma argsused

int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
    return 1;
}

//---------------------------------------------------------------------------

void __fastcall TForm2::Button1Click(TObject *Sender)
{
    Close();
}

//---------------------------------------------------------------------------
#include <vcl.h>
#include <windows.h>
#pragma hdrstop
#include "unit2.h"

extern "C" __declspec(dllexport) __stdcall int LoadForm();

#pragma argsused

int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
    return 1;
}

//---------------------------------------------------------------------------
int __stdcall LoadForm()
{
    TForm2 *Form2;

    Form2 = new TForm2(NULL);
    Form2->ShowModal();
    delete Form2;
    return 1;
}

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "Unit1.h"

extern "C" __declspec(dllimport) __stdcall int LoadForm();
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"

TForm1 *Form1;

//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
                 : TForm(Owner)
{
}

//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
    int iRet;
    iRet = LoadForm();
}

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "Unit1.h"
#pragma package(smart_init)
#pragma resource "*.dfm"

TForm1 *Form1;

typedef int (__stdcall *MYDLLFUNC)(void);
				
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner)
{
}

//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
    HINSTANCE hinstDLL;
    MYDLLFUNC ImpFuncDLL;
    int iRet;

    if ((hinstDLL=LoadLibrary("Project1.dll"))) {
        ImpFuncDLL = GetProcAddress(hinstDLL, "LoadForm");
        if (ImpFuncDLL) {
            iRet = ImpFuncDLL();
        }
        FreeLibrary(hinstDLL);
    }
}

//---------------------------------------------------------------------------

extern "C" __declspec(dllexport) __stdcall TDateTime AddDayToDate(TDateTime dt, int nbDay);

// Add a number of days to a Date and returns the new date (dummy sample)
TDateTime __stdcall AddDayToDate(TDateTime dt, int nbDay)
{
    dt += nbDay;
    return dt;
}

typedef TDateTime (__stdcall *MYDLLFUNC2) (TDateTime dt, int nbDay);

void __fastcall TForm3::Button1Click(TObject *Sender)
{
    HINSTANCE hinstDLL;
    MYDLLFUNC2 ImpFuncDLL;
    TDateTime dtAfter, dtBefore;
    int iRet;

    if ((hinstDLL=LoadLibrary("Project1.dll"))) {
        ImpFuncDLL = (MYDLLFUNC2)GetProcAddress(hinstDLL, "AddDayToDate");
        if (ImpFuncDLL) {
            dtBefore = TDateTime::CurrentDateTime();
            dtAfter = ImpFuncDLL(dtBefore,1);
        }
        FreeLibrary(hinstDLL);
    }
}

• la DLL
• le fichier d'en-tête, ou du moins les noms des fonctions contenues dans la DLL et leurs paramètres, afin de pouvoir en déclarer les prototypes.

#ifdef __DLL__
#define IMPORT_EXPORT __declspec(dllexport)
#else
#define IMPORT_EXPORT __declspec(dllimport)
#endif

//---------------------------------------------------------------------------
IMPORT_EXPORT class foo {
    public:
        int N1, N2, Result;
        void __stdcall AddN();
        int __stdcall GetResult();
        foo();
};

#include "foo.h"

foo::foo()
{
    N1 =0;
    N2 =0;
    Result=0;
}

void __stdcall foo::AddN()
{
    Result = N1 + N2;
}

int __stdcall foo::GetResult()
{
    return Result;
}

void __fastcall TForm3::Button2Click(TObject *Sender)
{
    int i Ret;
    foo *Foo;

    Foo = new foo();
    Foo->N1 = 5;
    Foo->N2 = 15;
    Foo->AddN();
    iRet = Foo->GetResult();
    delete Foo;
}

• celui de la fenêtre principale de l'application
• celui de la fenêtre contenue dans la DLL.

extern "C" __declspec(dllexport) __stdcall int LoadForm(HWND HWnd);

//..... 

int __stdcall LoadForm(HWND HWnd)
{
    HWND OldHandle;
    
    OldHandle = Application->Handle;
    Application->Handle = HWnd;
    Form2 = new TForm2(NULL);
    Form2->ShowModal();
    delete Form2;
    Application->Handle = OldHandle;
    return 1;
}

typedef int (__stdcall *MYDLLFUNC) (HWND HWnd);

void __fastcall TForm3::Button1Click(TObject *Sender)
{
    HINSTANCE hinstDLL;
    MYDLLFUNC ImpFuncDLL;
    
    if ((hinstDLL=LoadLibrary("Project1.dll"))) {
    ImpFuncDLL = (MYDLLFUNC)GetProcAddress(hinstDLL, "LoadForm");
    if (ImpFuncDLL) {
        iRet = ImpFuncDLL(Application->Handle);
    }
        FreeLibrary(hinstDLL);
    }
}