MFC Fail to Load Dlg from DLL - c++

I have installed in my PC VS2008 and Windows Mobile 6 SDK.
I have made a SmartDevice MFC application and a Regular DLL MFC, both uses shared MFC DLL.
But when I called DoModal() of the DLL the application hangs, show a "Debug Assertion Failed" message and freeze my device.
Can you help me?
Codes:
The EXE code:
typedef BOOL (CALLBACK* LPFNDLLLOAD)();
typedef BOOL (CALLBACK* LPFNDLLRUN)(HINSTANCE, HWND, LPBYTE *, LONG *);
BOOL CTesteExeDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// Set the icon for this dialog. The framework does this automatically
// when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon
//CModule mod;
//mod.Create(L"\\Program Files\\PMA\\Teste.dll");
//mod.Run(AfxGetInstanceHandle(), GetSafeHwnd(), 0, 0);
HMODULE m_hModule = AfxLoadLibrary(L"\\Program Files\\PMA\\TesteDll.dll");
LPFNDLLLOAD m_lpfnLoad= (LPFNDLLLOAD)GetProcAddress(m_hModule, _T("_Load"));
LPFNDLLRUN m_lpfnRun = (LPFNDLLRUN)GetProcAddress(m_hModule, _T("_Run"));
m_lpfnLoad();
m_lpfnRun(AfxGetInstanceHandle(), GetSafeHwnd(), 0, 0);
return TRUE; // return TRUE unless you set the focus to a control
}
The DLL Code:
I remove default CTesteDllApp class and put this:
#include "stdafx.h"
#include "TesteDll.h"
#include "TesteDllDlg.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif
extern "C" BOOL PASCAL EXPORT _Load()
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());
return TRUE;
}
extern "C" BOOL PASCAL EXPORT _Unload()
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());
return TRUE;
}
extern "C" BOOL WINAPI EXPORT _Run(HINSTANCE hInst,
HWND hwndParent,
LPBYTE *buffer,
LONG *size)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());
CTesteDllDlg d;
d.DoModal(); ////-------------> Error Here
return FALSE;
}
The DLL Dlg code:
BOOL CTesteDllDlg::OnInitDialog()
{
CDialog::OnInitDialog();
AfxMessageBox(L"Oi");
return TRUE; // return TRUE unless you set the focus to a control
// EXCEPTION: OCX Property Pages should return FALSE
}
The def File in DLL
; TesteDll.def : Declares the module parameters for the DLL.
LIBRARY "TesteDll"
EXPORTS
; Explicit exports can go here
_Load #1
_Unload #2
_Run #3

In a similar problem, I had to use AFX_MANAGE_STATE macro in the OnInitDialog, OnKillActive and OnSize methods of the DLL dialog. I had to add OnKillActive and OnSize methods just to call the mentioned macro, they do nothing but to call the macro, then base implementation, and return. Maybe it would work for your case.

Related

Access violation when invoking a C++ DLL from Delphi

I write a Unicode DLL in Visual C++ 6.0. Then try to invoke the DLL function from Delphi XE3.
When I debug in Delphi, when step over the line to invoke the DLL function, I will always get an Access violation exception.
However, when I debug in Visual C++, I can see all parameters passed from Delphi are correct and I can step over all codelines without any exceptions.
If running outside the debugger, then I will not see any "access violation exceptions.
I try many methods but still cannot figure out how to eliminate the exception when debuggin in Delphi.
Below is the code in Visual C++ 6.0 part:
TestDLL.cpp:
extern "C" VOID WINAPI Test(CONST MESSAGEPROC lpMessageProc, LPVOID lParam)
{
if (lpMessageProc != NULL)
(*lpMessageProc)(1500, (const LPVOID)(LPCTSTR)CString((LPCSTR)IDS_MYTEST), lParam);
/*
if (lpMessageProc != NULL)
(*lpMessageProc)(1500, (const LPVOID)(LPCTSTR)CString(_T("Test")), lParam);*/
}
TestDLL.h:
// TestDLL.h : main header file for the TESTDLL DLL
//
#if !defined(AFX_TESTDLL_H__38054A53_5CEE_4ABF_9BA8_BCE427FCB8E1__INCLUDED_)
#define AFX_TESTDLL_H__38054A53_5CEE_4ABF_9BA8_BCE427FCB8E1__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#ifndef __AFXWIN_H__
#error include 'stdafx.h' before including this file for PCH
#endif
#include "resource.h" // main symbols
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
typedef BOOL (CALLBACK* MESSAGEPROC)(CONST DWORD dwMessageId, CONST LPVOID lp, LPVOID lParam);
VOID WINAPI Test(CONST MESSAGEPROC lpMessageProc, LPVOID lParam);
#ifdef __cplusplus
}
#endif
/////////////////////////////////////////////////////////////////////////////
//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.
#endif // !defined(AFX_TESTDLL_H__38054A53_5CEE_4ABF_9BA8_BCE427FCB8E1__INCLUDED_)
Below is the codes in Delphi XE3 part:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
public
{ Public declarations }
end;
PForm1 = ^TForm1;
TMessageProc = function (const dwMessageId: DWORD; const lp: Pointer; lParam: Pointer): BOOL; stdcall;
{$EXTERNALSYM TMessageProc}
var
Form1: TForm1;
procedure Test(const lpMessageProc: TMessageProc; lParam: Pointer); stdcall;
implementation
{$R *.dfm}
procedure Test; external 'TestDLL.dll' index 2;
function MessageProc(const dwMessageId: DWORD; const lp: Pointer; lParam: Pointer): BOOL; stdcall;
begin
Result := True;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
Test(MessageProc, #Self); // <---- This code line will cause "access violation
end;
I belive the problem occurs in DLL test function, when it try to load string from resource using CString((LPCSTR)IDS_MYTEST). If I change the code to CString(_T("Test")), then problem disappears.
Thanks
As you surmised, this statement will not work:
CString((LPCSTR)IDS_MYTEST)
Although this constructor of CString does allow you to pass it a resource ID, it will try to find the resource in the calling process's (ie, the Delphi EXE's) resources, not in the DLL's resources. You need to use the HINSTANCE of the DLL, as provided by the DLL's DllMain(), when loading strings from the DLL's resources. You can use the CString::LoadString() method for that, eg:
HINSTANCE hInst;
BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
hInst = hinstDLL;
return TRUE;
}
extern "C" VOID WINAPI Test(CONST MESSAGEPROC lpMessageProc, LPVOID lParam)
{
if (lpMessageProc != NULL)
{
CString str;
str.LoadString(hInst, IDS_MYTEST);
(*lpMessageProc)(1500, (LPCTSTR)str, lParam);
}
}
I finally figure out this is a bug of MFC codes(VC6.0 version).
I don't know if I can post MFC source codes so I will just paste the function headers and related parts only.
In Microsoft Visual Studio\VC98\MFC\SRC\STRCORE.CPP, we can see the following 3 functions:
//////////////////////////////////////////////////////////////////////////////
// More sophisticated construction
CString::CString(LPCTSTR lpsz) // Function 1
{
Init();
if (lpsz != NULL && HIWORD(lpsz) == NULL)
{
UINT nID = LOWORD((DWORD)lpsz);
if (!LoadString(nID))
TRACE1("Warning: implicit LoadString(%u) failed\n", nID);
}
else
{
// Construct string normally
}
}
/////////////////////////////////////////////////////////////////////////////
// Special conversion constructors
#ifdef _UNICODE
CString::CString(LPCSTR lpsz) // Function 2
{
// Construct string normally
}
#else //_UNICODE
CString::CString(LPCWSTR lpsz) // Function 3
{
// Construct string normally
}
#endif //!_UNICODE
As we can see in the above code snippet, only function 1 contains codes that will take special process on lpsz and check if it is a string resource ID, if yes, then load the string from the resource. Both function 2 & 3 have no such special processes.
When we create a project in VS6, the default settings for a project is _MBCS, in such a case, function 1 will become
CString::CString(LPCSTR lpsz)
so CString((LPCSTR)nResID) will actually invoke function 1 and load string resource properly.
Function 2 will be disabled since _UNICODE is not defined. And function 3 works with wide char strings.
Therefore, for _MBCS project, everything works perfectly and consistently with the MSDN document.
However, when I change _MBCS to _UNICODE, function 1 will become
CString::CString(LPCWSTR lpsz)
Fucntion 2 will be enabled and function 3 will be disabled.
So CString((LPCSTR)nResID) will actually invoke function 2, which does NOT have special process to load string resource, which makes the problem.
There are two solutions for this problem:
Always use CString((LPCTSTR)nResID) instead of CString((LPCSTR)nResID) to load a string from resource. However, this usage is inconsistent with MSDN document so we have to call it as an undocumented usage.
Always use LoadString to load a string resource.
Though solution 1 is a little simpler, it is an undocumented usage so I finally opt solution 2 to solve my problem.
Many thanks to all your helps in solving this issue.

Issue debugging an MFC applicaiton, building but not running

I build the code successfully but it does not debug and comes up with this warning in a wizard miscellaneous code.
"Warning: Destroying non-NULL m_pMainWnd\n"
and
"Warning: Temp map lock count non-zero (%ld).\n",
The aim of this is to create a dialog box that allows a user to input car specifications and a track so a lap time can be calculated.
Source File of Main Dialogue box:
#define _WIN32_WINNT 0x0601
// LapTimeSim.cpp : implementation file
//
#include <iostream>
#include "stdafx.h"
#include "LapTimeSim.h"
#include "afxdialogex.h"
#include "SecondDlg.h"
#include "resource.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif
using namespace std;
// LapTimeSim dialog
IMPLEMENT_DYNAMIC(LapTimeSim, CDialogEx);
LapTimeSim::LapTimeSim(CWnd* pParent /*=NULL*/)
: CDialogEx(IDD_DIALOG1, pParent)
{
}
LapTimeSim::~LapTimeSim()
{
}
void LapTimeSim::DoDataExchange(CDataExchange* pDX)
{
CDialogEx::DoDataExchange(pDX);
}
BEGIN_MESSAGE_MAP(LapTimeSim, CDialogEx)
ON_BN_CLICKED(IDC_CAR, &LapTimeSim::OnBnClickedCar)
ON_BN_CLICKED(IDGO, &LapTimeSim::OnBnClickedGo)
ON_BN_CLICKED(IDC_TRACK, &LapTimeSim::OnBnClickedTrack)
END_MESSAGE_MAP()
// LapTimeSim message handlers
void LapTimeSim::OnBnClickedCar()
{
// TODO: Add your control notification handler code here
CSecondDlg Dlg;
Dlg.DoModal();
}
void LapTimeSim::OnBnClickedGo()
{
// TODO: Add your control notification handler code here
}
void LapTimeSim::OnBnClickedTrack()
{
// TODO: Add your control notification handler code here
}
A Large Header; Header file of main dialog box
==============
#pragma once
// LapTimeSim dialog
class LapTimeSim : public CDialogEx
{
DECLARE_DYNAMIC(LapTimeSim)
public:
LapTimeSim(CWnd* pParent = NULL); // standard constructor
virtual ~LapTimeSim();
// Dialog Data
#ifdef AFX_DESIGN_TIME
enum { IDD = IDD_DIALOG1 };
#endif
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
DECLARE_MESSAGE_MAP()
public:
afx_msg void OnBnClickedCar();
afx_msg void OnBnClickedGo();
afx_msg void OnBnClickedTrack();
};
Source File of Main Dialogue box:
// SecondDlg.cpp : implementation file
//
#define _WIN32_WINNT 0x0601
#include <iostream>
#include "stdafx.h"
#include "LapTimeSim.h"
#include "afxdialogex.h"
#include "SecondDlg.h"
#include "resource.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif
// CSecondDlg dialog
IMPLEMENT_DYNAMIC(CSecondDlg, CDialog)
CSecondDlg::CSecondDlg(CWnd* pParent /*=NULL*/)
: CDialog(IDD_DIALOG2, pParent)
{
}
CSecondDlg::~CSecondDlg()
{
}
void CSecondDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
}
BEGIN_MESSAGE_MAP(CSecondDlg, CDialog)
END_MESSAGE_MAP()
// CSecondDlg message handlers
A Large Header; Header file of second dialog box
==============
#pragma once
// CSecondDlg dialog
class CSecondDlg : public CDialog
{
DECLARE_DYNAMIC(CSecondDlg)
public:
CSecondDlg(CWnd* pParent = NULL); // standard constructor
virtual ~CSecondDlg();
// Dialog Data
#ifdef AFX_DESIGN_TIME
enum { IDD = IDD_DIALOG2 };
#endif
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
DECLARE_MESSAGE_MAP()
};
Source File : appmodule.cpp writeen by the wizard
// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and related
// electronic documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft Foundation Classes product.
#include "stdafx.h"
#include "sal.h"
/////////////////////////////////////////////////////////////////////////////
// export WinMain to force linkage to this module
extern int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
_In_ LPTSTR lpCmdLine, int nCmdShow);
extern "C" int WINAPI
_tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
_In_ LPTSTR lpCmdLine, int nCmdShow)
#pragma warning(suppress: 4985)
{
// call shared/exported WinMain
return AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
}
/////////////////////////////////////////////////////////////////////////////
// initialize app state such that it points to this module's core state
BOOL AFXAPI AfxInitialize(BOOL bDLL, DWORD dwVersion)
{
AFX_MODULE_STATE* pModuleState = AfxGetModuleState();
pModuleState->m_bDLL = (BYTE)bDLL;
ASSERT(dwVersion <= _MFC_VER);
UNUSED(dwVersion); // not used in release build
#ifdef _AFXDLL
pModuleState->m_dwVersion = dwVersion;
#endif
#ifdef _MBCS
// set correct multi-byte code-page for Win32 apps
if (!bDLL)
_setmbcp(_MB_CP_ANSI);
#endif //_MBCS
return TRUE;
}
// force initialization early
#pragma warning(disable: 4074)
#pragma init_seg(lib)
#ifndef _AFXDLL
void AFX_CDECL _AfxTermAppState()
{
// terminate local data and critical sections
AfxTermLocalData(NULL, TRUE);
AfxCriticalTerm();
// release the reference to thread local storage data
AfxTlsRelease();
}
#endif
#ifndef _AFXDLL
char _afxInitAppState = (char)(AfxInitialize(FALSE, _MFC_VER), atexit(&_AfxTermAppState));
#else
char _afxInitAppState = (char)(AfxInitialize(FALSE, _MFC_VER));
#endif
/////////////////////////////////////////////////////////////////////////////
Source File - Wizard code coming up with warning:
// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and related
// electronic documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft Foundation Classes product.
#include "stdafx.h"
#include "sal.h"
/////////////////////////////////////////////////////////////////////////////
// Standard WinMain implementation
// Can be replaced as long as 'AfxWinInit' is called first
int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
_In_ LPTSTR lpCmdLine, int nCmdShow)
{
ASSERT(hPrevInstance == NULL);
int nReturnCode = -1;
CWinThread* pThread = AfxGetThread();
CWinApp* pApp = AfxGetApp();
// AFX internal initialization
if (!AfxWinInit(hInstance, hPrevInstance, lpCmdLine, nCmdShow))
goto InitFailure;
// App global initializations (rare)
if (pApp != NULL && !pApp->InitApplication())
goto InitFailure;
// Perform specific initializations
if (!pThread->InitInstance())
{
if (pThread->m_pMainWnd != NULL)
{
TRACE(traceAppMsg, 0, "Warning: Destroying non-NULL m_pMainWnd\n");
pThread->m_pMainWnd->DestroyWindow();
}
nReturnCode = pThread->ExitInstance();
goto InitFailure;
}
nReturnCode = pThread->Run();
InitFailure:
#ifdef _DEBUG
// Check for missing AfxLockTempMap calls
if (AfxGetModuleThreadState()->m_nTempMapLock != 0)
{
TRACE(traceAppMsg, 0, "Warning: Temp map lock count non-zero (%ld).\n",
AfxGetModuleThreadState()->m_nTempMapLock);
}
AfxLockTempMaps();
AfxUnlockTempMaps(-1);
#endif
AfxWinTerm();
return nReturnCode;
}
/////////////////////////////////////////////////////////////////////////////
(See my answer to this SO: Cannot create main window?, it looks very similar to your issue)
If you have created this project with wizard then you should also have source files for CWinApp implementation. If its some other kind of wizard generated application then you still should somewhere have an InitInstance like method. with following lines of code:
LapTimeSim dlg;
m_pMainWnd = &dlg;
INT_PTR nResponse = dlg.DoModal();
(I assume here that LapTimeSim is your main entry dialog). If you remove above lines, you will get the exact same trace and behaviour as in your description (I checked this locally).
So you should check if you have by mistake removed them, or recreate project from MFC template wizard.

how to make a *.dll WinAmp plugin work on a friends pc

I just made this very simple .dll plugin for Winamp. It works perfectly fine on my pc but I made it for a friend who requested this. Its the first time I use Visual Studio 2013
and make dll files with c++... my problem is that i can't really figure out why it doesn't work on his pc, I think its an export problem but I am not entirely sure.
#include "stdafx.h"
#include <windows.h>
#include "gen_InfinitePlay.h"
#include "wa_ipc.h"
#include <stdio.h>
using namespace System;
using namespace System::Threading;
// these are callback functions/events which will be called by Winamp
int init(void);
void config(void);
void quit(void);
// this structure contains plugin information, version, name...
// GPPHDR_VER is the version of the winampGeneralPurposePlugin (GPP) structure
winampGeneralPurposePlugin plugin = {
GPPHDR_VER, // version of the plugin, defined in "gen_InfinitePlay.h"
PLUGIN_NAME, // name/title of the plugin, defined in "gen_InfinitePlay.h"
init, // function name which will be executed on init event
config, // function name which will be executed on config event
quit, // function name which will be executed on quit event
0, // handle to Winamp main window, loaded by winamp when this dll is loaded
0 // hinstance to this dll, loaded by winamp when this dll is loaded
};
void play(){
while (true){
if (SendMessage(plugin.hwndParent, WM_WA_IPC, 0, IPC_ISPLAYING) != 1)
SendMessage(plugin.hwndParent, WM_WA_IPC, 0, IPC_STARTPLAY);
Sleep(60000);
}
}
// event functions follow
int init() {
Thread^ t = gcnew Thread(gcnew ThreadStart(play));
t->Start();
return 0;
}
void config() {
//A basic messagebox that tells you the 'config' event has been triggered.
//You can change this later to do whatever you want (including nothing)
//MessageBox(plugin.hwndParent, L"Config event triggered for gen_InfinitePlay.", L"", MB_OK);
}
void quit() {
//A basic messagebox that tells you the 'quit' event has been triggered.
//If everything works you should see this message when you quit Winamp once your plugin has been installed.
//You can change this later to do whatever you want (including nothing)
//MessageBox(0, L"Quit event triggered for gen_InfinitePlay.", L"", MB_OK);
}
// This is an export function called by winamp which returns this plugin info.
// We wrap the code in 'extern "C"' to ensure the export isn't mangled if used in a CPP file.
extern "C" __declspec(dllexport) winampGeneralPurposePlugin * winampGetGeneralPurposePlugin() {
return &plugin;
}
You are missing the Visual Studio 2013 runtime. The proper way to install this is via the Visual Studio 2013 redistributable.
http://www.microsoft.com/en-us/download/details.aspx?id=40784
MSVCR120.DLL was missing, its probably not the "right" way to make it work but I just copied mine to his plugin dir... I still think it could be solved by some export flags or something but I am to lazy for this

Windows 7 taskbar state with minimal code

What would be the shortest code to set the state of a Windows 7 taskbar button for a known window handle?
The goal is to write a console utility that changes the progress and state (colour) of the console window taskbar item from a batch script. While the script performs different tasks, the taskbar item of its console window should represent the current state.
I get the window handle with the GetConsoleWindow() function, but then it seems to require loads of COM and Shell API stuff that I don't understand. One example I've found uses a whole GUI application with MFC to demonstrate the API, but most of it is way too complicated for my little tool and I don't understand it well enough to remove the stuff I don't need.
The tool should compile on Windows 7 with VS2010 (C++) but also run on earlier Windows versions (doing nothing if a feature is not available).
I created a class to set the progress in the Win7 taskbar for a project at one time. It's a wrapper for the ITaskBarList3 interface available from the Windows Shell. It's specifically done with ITaskBarList3.SetProgressState and ITaskBarList3.SetProgressValue functions.
This is the code I dug up:
#include <shobjidl.h>
#include <windows.h>
#pragma comment(lib, "Shell32.lib")
#pragma comment(lib, "Ole32.lib")
class Win7TaskbarProgress
{
public:
Win7TaskbarProgress();
virtual ~Win7TaskbarProgress();
void SetProgressState(HWND hwnd, TBPFLAG flag);
void SetProgressValue(HWND hwnd, ULONGLONG ullCompleted, ULONGLONG ullTotal);
private:
bool Init();
ITaskbarList3* m_pITaskBarList3;
bool m_bFailed;
};
Win7TaskbarProgress::Win7TaskbarProgress()
{
m_pITaskBarList3 = NULL;
m_bFailed = false;
}
Win7TaskbarProgress::~Win7TaskbarProgress()
{
if (m_pITaskBarList3)
{
m_pITaskBarList3->Release();
CoUninitialize();
}
}
void Win7TaskbarProgress::SetProgressState( HWND hwnd, TBPFLAG flag )
{
if (Init())
m_pITaskBarList3->SetProgressState(hwnd, flag);
}
void Win7TaskbarProgress::SetProgressValue( HWND hwnd, ULONGLONG ullCompleted, ULONGLONG ullTotal )
{
if (Init())
m_pITaskBarList3->SetProgressValue(hwnd, ullCompleted, ullTotal);
}
bool Win7TaskbarProgress::Init()
{
if (m_pITaskBarList3)
return true;
if (m_bFailed)
return false;
// Initialize COM for this thread...
CoInitialize(NULL);
CoCreateInstance(CLSID_TaskbarList, NULL, CLSCTX_INPROC_SERVER, IID_ITaskbarList3, (void **)&m_pITaskBarList3);
if (m_pITaskBarList3)
return true;
m_bFailed = true;
CoUninitialize();
return false;
}
Note you still need to call RegisterWindowMessage("TaskbarButtonCreated") and ChangeWindowMessageFilterEx() to setup an message filter before SetProgressValue() can work.
According to the MSDN docs you are supposed to recreate your object each time you get the created message but I found I just had to do the ChangeWindowMessageFilterEx() and it works fine for normal circumstances.

"Unresolved external _WinMain#16" if I move WndProc to another cpp file

For a Windows application I'm trying to get CreateWindow() and WndProc() (or my versions of them) to be part of a singleton class that is created at the beginning of _tWinMain() but since trying to shift the functions to GameHandler.h and GameHandler.cpp I keep getting "unresolved external symbol _WinMain#16". They were originally global functions in main.cpp and everything was compiling fine then I decided to move them to GameHandler and ever since all I get is the unresolved external, even if I try to move them back to main.cpp.
I'm doing this in VS2010, the project was created as a Windows Application and there's no specific entry point set in properties (I double checked as every solution I've found so far says that it's because it's a console app - this isn't).
The code I currently have is shown below. The actual project has a couple of thousand lines of other code that I've left out as I don't think it's relevant (but will happily proved wrong. While the actual window creation code is related, I don't think the code itself is the problem (apart from what I left in), it's the location of GameWindowProc() &/or CreateGameWindow() or how they're called. The actual window creation code is taken from NeHe's tutorial. Trying to compile the following code only gives the aforementioned unresolved external.
main.cpp:
#include <Windows.h>
#include "GameManager.h"
#ifndef USEGMGR
bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag);
LRESULT CALLBACK GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
#endif
int APIENTRY _tWinMain(HINSTANCE hInst, HINSTANCE hPrevInst,
LPTSTR lpCmdLine, int nCmdShow)
{
GameManager::Startup();
GameManager* GMgr = GameManager::GetInstance();
GMgr->SetProgramState(GAME_MODE);
while(GMgr->GetProgramState() != GAME_MODE) // Normally this would be if (State != GAME_QUIT)
{ /* do game related stuff */ }
GameManager::Shutdown();
return 0;
}
#ifndef USEGMGR
bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag)
{
// Fairly complex but flexible creation code, taken from NeHe's tutorials. Of relevant interest is:
WNDCLASS wc; // Windows Class Structure
wc.lpfnWndProc = (WNDPROC) GameWindowProc; // WndProc Handles Messages
if (!RegisterClass(&wc)) // Attempt To Register The Window Class
{
MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return false;
}
return true;
}
LRESULT CALLBACK GameWindowProc(HWND hWnd, // Handle For This Window
UINT uMsg, // Message For This Window
WPARAM wParam, // Additional Message Information
LPARAM lParam) // Additional Message Information
{
// various custom message handling, if not processed:
return DefWindowProc(hWnd,uMsg,wParam,lParam);
}
#endif
in GameManager.h:
#ifndef GAMEMANAGER_H
#define GAMEMANAGER_H
#define USEGMGR // makes CreateGameWindow() and GameWindowProc() methods in GameManager instead of global
#include <Windows.h>
enum ProgramState
{
GAME_MODE,
GAME_QUIT,
};
class GameManager
{
public:
static void Startup();
static void Shutdown();
static GameManager* GetInstance();
void Update(); // code not shown, check quit key etc
#ifdef USEGMGR
const bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag);
static LRESULT CALLBACK GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
#endif
void KillGameWindow(void);
const int GetProgramState() const;
void SetProgramState(const int& newMode);
private:
GameManager();
~GameManager();
GameManager(const GameManager&);
GameManager& operator=(const GameManager&);
HINSTANCE m_hInstance;
HWND m_hWnd;
HDC m_hDC;
static GameManager* s_instance;
int m_programState; // uses ProgramState enum
};
#endif
in GameManager.cpp:
#include "GameManager.h"
#include <Windows.h>
#include <assert.h>
#ifndef USEGMGR
extern bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag);
#endif
GameManager* GameManager::s_instance = NULL;
GameManager::GameManager(){}
GameManager::~GameManager(){}
void GameManager::Startup()
{
assert(s_instance == NULL);
s_instance = new GameManager;
#ifdef USEGMGR
if (! (s_instance->CreateGameWindow("Game Window", 800, 600, 32, true )) )
#else
if (! (CreateGameWindow("Game Window", 800, 600, 32, true )) )
#endif
assert("CreateGameWindow failed! Need an error here"); // Quit If Window Was Not Created - clean this up later
}
void GameManager::Shutdown()
{
assert(s_instance != NULL);
delete s_instance;
s_instance = NULL;
}
GameManager* GameManager::GetInstance(){return s_instance;}
void GameManager::Update(){/* msg handling, watch for quit key, etc */}
const int GameManager::GetProgramState() const{return s_instance->m_programState;}
void GameManager::SetProgramState(const int& newState){s_instance->m_programState = newState;}
#ifdef USEGMGR
const bool GameManager::CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag)
{
// Fairly complex but flexible creation code, taken from NeHe's tutorials. Of relevant interest is:
WNDCLASS wc; // Windows Class Structure
wc.lpfnWndProc = (WNDPROC) GameManager::GameWindowProc; // WndProc Handles Messages
if (!RegisterClass(&wc)) // Attempt To Register The Window Class
{
MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return false;
}
return true;
}
LRESULT CALLBACK GameManager::GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
// various custom message handling, if not processed:
return DefWindowProc(hWnd,uMsg,wParam,lParam);
}
#endif
As you can see, I've set up some preprocessor conditionals to switch between the troublesome functions being in main.cpp or as part of GameManager. Comment out #define USEGMGR at the beginning of GameManager.h to have them as global funcs in main.cpp.
Can someone please tell me what I'm doing wrong?
Edit: removed comment about not being able to quit if you get it to run.
The WinMain function cannot be a member function of a class, even a "singleton" class.
Since it functions as the "entry point" for the program, essentially replacing the main function you'd find in a traditional C++ application, it needs to be a free global function.
The message Unresolved external _WinMain#16 is simply the compiler's cryptic way of telling you that it cannot locate the expected entry point, named WinMain (plus some name mangling).
Add
#include <tchar.h>
to the top of main.cpp so that the _tWinMain macro gets defined properly.
What happens if you don't have the macro definition is that you end up with a function named _tWinMain() (or some mangled version of the name like ?_tWinMain##YGHPAUHINSTANCE__##0PADH#Z()) in the object file, but the linker and runtime initialization code are looking for WinMain() or wWinMain(). They don't find it.
<tchar.h> defines a macro that transforms the name _tWinMain() into one of the two names everything else is looking for. You must have had something including that header before you started your refactoring (quite possibly indirectly), and lost it somehow.
Or you can dispense with the macro version and name the function WinMain or wWinMain (either one should work, regardless of whether you're building for UNICODE or not). If you do that, just remember to change the LPTSTR parameter declaration to match the one you choose.