how to use a class method as a WIN32 application callback method (WINPROC)... Error static struct HI
- by numerical25
I am receiving errors and at the same time trying to make this work so please read what I got to say. Thanks....
I am creating a c++ application and majority of the application is encapsulated into a class. That means that my WinProc function is a static class method that I use as my call back method for my win32 application. The problem is that since I created that as a win32 application, every class member I use inside that method has to be static as well. Including my HINSTANCE class which I use inside of it. Now I receive this error
error LNK2001: unresolved external symbol "public: static struct HINSTANCE__
I need to figure out how to make this all work and below is my class declaration. My static member static HINSTANCE m_hInst is causing the error I believe.
#pragma once
#include "stdafx.h"
#include "resource.h"
#define MAX_LOADSTRING 100
class RenderEngine {
protected:
int m_width;
int m_height;
ATOM RegisterEngineClass();
public:
static HINSTANCE m_hInst; //<------ This is causing the error
HWND m_hWnd;
int m_nCmdShow;
TCHAR m_szTitle[MAX_LOADSTRING]; // The title bar text
TCHAR m_szWindowClass[MAX_LOADSTRING]; // the main window class name
bool InitWindow();
bool InitDirectX();
bool InitInstance();
//static functions
static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam);
int Run();
};
Below is the implementation
#include "stdafx.h"
#include "RenderEngine.h"
bool RenderEngine::InitWindow()
{
RenderEngine::m_hInst = NULL;
// Initialize global strings
LoadString(m_hInst, IDS_APP_TITLE, m_szTitle, MAX_LOADSTRING);
LoadString(m_hInst, IDC_RENDERENGINE, m_szWindowClass, MAX_LOADSTRING);
if(!RegisterEngineClass())
{
return false;
}
if(!InitInstance())
{
return false;
}
return true;
}
ATOM RenderEngine::RegisterEngineClass()
{
WNDCLASSEX wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = RenderEngine::WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = m_hInst;
wcex.hIcon = LoadIcon(m_hInst, MAKEINTRESOURCE(IDI_RENDERENGINE));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCE(IDC_RENDERENGINE);
wcex.lpszClassName = m_szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassEx(&wcex);
}
LRESULT CALLBACK RenderEngine::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
switch (message)
{
case WM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(m_hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code here...
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
bool RenderEngine::InitInstance()
{
m_hWnd = NULL;
m_hWnd = CreateWindow(m_szWindowClass, m_szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, m_hInst, NULL);
if (!m_hWnd)
{
return FALSE;
}
if(!ShowWindow(m_hWnd, m_nCmdShow))
{
return false;
}
UpdateWindow(m_hWnd);
return true;
}
// Message handler for about box.
INT_PTR CALLBACK RenderEngine::About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;
case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}
int RenderEngine::Run()
{
MSG msg;
HACCEL hAccelTable;
hAccelTable = LoadAccelerators(m_hInst, MAKEINTRESOURCE(IDC_RENDERENGINE));
// Main message loop:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
and below is the code being used within the WinMain
RenderEngine go;
int APIENTRY _tWinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPTSTR lpCmdLine,
int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: Place code here.
RenderEngine::m_hInst = hInstance;
go.m_nCmdShow = nCmdShow;
if(!go.InitWindow())
{
return 0;
}
go.Run();
return 0;
}
If anything does not make any sense, then I apologize, I am a newb. Thanks for the help!!
