Hitting the PostMessage command , but unable to go inside the wndProc for that posted message.
What I have tried:
#include "framework.h"
#include "CombinedPostMessageAndPostThreadMessageNature.h"
#include <string>
#define MAX_LOADSTRING 100
HINSTANCE hInst;
WCHAR szTitle[MAX_LOADSTRING];
WCHAR szWindowClass[MAX_LOADSTRING];
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
#define WM_MSGSSENTVIAPOSTMSG WM_USER+ 1
#define WM_MSGSSENTVIAPOSTTHREADMSG WM_USER+ 2
DWORD MainThreadID;
HWND MainWnd;
bool PostThreadMessageWantToHandledByWndProc = true;
bool PostThreadMessageWantToHandledManually = false;
void CreateUserThread(DWORD);
void SendMessageFromAnotherThread(LPVOID);
void PostThreadMessageMessageHandlerViaWndProc();
void PostThreadMessageMessageHandlerViaManually();
void RedirectorForPostThreadMessageMessageHandlerViaWndProc(MSG);
void RedirectorForPostThreadMessageMessageHandlerViaManually(MSG);
void GeneratePostMessage();
void PostMessageMessageHandlerViaWndProc();
void SendPostMessageWithNullWndHandle();
int APIENTRY wWinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ LPWSTR lpCmdLine, _In_ int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_COMBINEDPOSTMESSAGEANDPOSTTHREADMESSAGENATURE, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
if (!InitInstance(hInstance, nCmdShow))
{
return FALSE;
}
MainThreadID = GetCurrentThreadId();
CreateUserThread(MainThreadID);
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_COMBINEDPOSTMESSAGEANDPOSTTHREADMESSAGENATURE));
MSG msg;
HWND hWndThread = (HWND)(-1);
while (GetMessage(&msg, hWndThread, 0, 0))
{
if (PostThreadMessageWantToHandledByWndProc)
{
RedirectorForPostThreadMessageMessageHandlerViaWndProc(msg);
PostThreadMessageWantToHandledByWndProc = false;
PostThreadMessageWantToHandledManually = false;
}
else if (PostThreadMessageWantToHandledManually)
{
RedirectorForPostThreadMessageMessageHandlerViaManually(msg);
}
else
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
}
return (int)msg.wParam;
}
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_COMBINEDPOSTMESSAGEANDPOSTTHREADMESSAGENATURE));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_COMBINEDPOSTMESSAGEANDPOSTTHREADMESSAGENATURE);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance;
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
if (!hWnd)
{
return FALSE;
}
MainWnd = hWnd;
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
switch (wmId)
{
case IDM_ABOUT:
DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
EndPaint(hWnd, &ps);
}
break;
case WM_MSGSSENTVIAPOSTTHREADMSG:
{
PostThreadMessageMessageHandlerViaWndProc();
GeneratePostMessage();
break;
}
case WM_MSGSSENTVIAPOSTMSG:
{
PostMessageMessageHandlerViaWndProc();
break;
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
INT_PTR CALLBACK 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;
}
void CreateUserThread(DWORD mainThreadID)
{
DWORD threadID = 0;
HANDLE hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)SendMessageFromAnotherThread, (LPVOID)mainThreadID, 0, &threadID);
if (hThread)
{
WaitForSingleObject(hThread, (DWORD)INFINITY);
return;
}
}
void SendMessageFromAnotherThread(LPVOID mainThreadID)
{
DWORD l_mainThreadID = (DWORD)mainThreadID;
Sleep(100);
PostThreadMessage(l_mainThreadID, WM_MSGSSENTVIAPOSTTHREADMSG, 0, 0);
}
void PostThreadMessageMessageHandlerViaWndProc()
{
MessageBox(NULL, L"Thread Message Sent Using PostThreadMessage", L" Thread Message Handled from WndProc", MB_ICONINFORMATION);
}
void PostThreadMessageMessageHandlerViaManually()
{
MessageBox(NULL, L"Thread Message Sent Using PostThreadMessage", L" Thread Message Handled Manually", MB_ICONINFORMATION);
}
void RedirectorForPostThreadMessageMessageHandlerViaWndProc(MSG msg)
{
if (msg.message == WM_MSGSSENTVIAPOSTTHREADMSG)
{
msg.hwnd = MainWnd;
DispatchMessage(&msg);
}
}
void RedirectorForPostThreadMessageMessageHandlerViaManually(MSG msg)
{
if (msg.message == WM_MSGSSENTVIAPOSTTHREADMSG)
{
PostThreadMessageMessageHandlerViaManually();
}
}
void GeneratePostMessage()
{
SendPostMessageWithNullWndHandle();
}
void PostMessageMessageHandlerViaWndProc()
{
MessageBox(NULL, L"Message Received from Post Message to a NULL Window(In The Current Thread)", L"MessageReceivedFromPostMessage", MB_ICONINFORMATION);
PostQuitMessage(0);
}
void SendPostMessageWithNullWndHandle()
{
MessageBox(NULL, L"Sending Message to a NULL Window(In The Current Thread)", L"PostMessageUsingPostMessage", MB_ICONINFORMATION);
Sleep(100);
auto lTime = GetCurrentTime();
PostMessage(NULL, WM_MSGSSENTVIAPOSTMSG, 0, lTime);
}