Использование собственной DLL

#include <Windows.h>
 
 
int WINAPI DllMain(HINSTANCE hInstance, DWORD fdw, PVOID pv)
{
    return TRUE;
}
 
 
extern "C" _declspec (dllexport) int CALLBACK TextRect(HDC hDC, RECT rect, char* str)
    {
        int length = strlen(str);
        SIZE sz;
        GetTextExtentPoint32(hDC, str, length, &sz);
        Rectangle(hDC, rect.left, rect.top, rect.right, rect.bottom);
        TextOut(hDC, (rect.right - rect.left - sz.cx) / 2 + rect.left, (rect.bottom - rect.top - sz.cy) / 2 + rect.top, str, length);
 
        return 0;
    }
 
extern "C" _declspec (dllexport) int CALLBACK SumInt(int x, int y)
{
    return x + y;
}

#include <Windows.h>
 
using namespace std;
 
LRESULT CALLBACK WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
HWND hWnd;
 
HINSTANCE hDllInstance;
 
typedef int(CALLBACK *TextRectDll)(HDC hDC, RECT rect, char* str);
typedef int(CALLBACK *SumIntDll)(int x, int y);
 
 
 
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    hDllInstance = LoadLibraryEx("MyDLL.dll", 0, DONT_RESOLVE_DLL_REFERENCES);
 
    WNDCLASSEX wc;
    MSG msg;
 
    ZeroMemory(&wc, sizeof(WNDCLASSEX));
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WinProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(0, IDC_ARROW);
    wc.hIconSm = LoadIcon(0, IDI_APPLICATION);
    wc.lpszClassName = "WinClass";
 
    RegisterClassEx(&wc);
    hWnd = CreateWindow("WinClass", "Untitled", WS_OVERLAPPEDWINDOW, (GetSystemMetrics(SM_CXSCREEN) / 2) - 300, (GetSystemMetrics(SM_CYSCREEN) / 2) - 300, 600, 600, 0, 0, hInstance, 0);
 
    ShowWindow(hWnd, nCmdShow);
        UpdateWindow(hWnd);
 
    while (GetMessage(&msg, 0, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
 
    return (int)msg.wParam;
}
 
LRESULT CALLBACK WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
 
    HDC             hDC;
    PAINTSTRUCT     PaintStruct;
 
    switch (msg)
    {
 
    case WM_PAINT:
    {
                     hDC = BeginPaint(hWnd, &PaintStruct);
 
                     SumIntDll SumInt = (SumIntDll)GetProcAddress(hDllInstance, "_SumInt@8");
                     TextRectDll TextRect = (TextRectDll)GetProcAddress(hDllInstance, "_TextRect@24");
 
                     RECT rc;
                     SetRect(&rc, 100, 100, 400, 400);
 
                     TextRect(hDC, rc, "Text");
 
                     
                     EndPaint(hWnd, &PaintStruct);
 
                     return 0;
    }
 
    case WM_DESTROY:
    {
                       FreeLibrary(hDllInstance);
                       PostQuitMessage(0);
                       return 0;
    }
 
 
    }
    return DefWindowProc(hWnd, msg, wParam, lParam);
}