Winapi c++: DialogBox hangs when breaking a loop - c++

Question

i've created s simple W32 application to cicle through two applications(hard coded window classes atm).
When i call the start button (IDC_Start) everything works fine, but when i change the focus to
hwnd the application hangs an cannot be closed. I just need a simple and clean method to
stop the loop, that start when calling IDC_Start. Any Help would be greatly apreciated!
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <windows.h>
#include <resource.h>
#include <iostream>
using namespace std;
BOOL CALLBACK DlgProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
HWND hwnd1,hwnd2;
hwnd1 = FindWindow("Notepad++",0);
hwnd2 = FindWindow("Notepad",0);
BOOL bDone;
switch(Message)
{
case WM_INITDIALOG:
// This is where we set up the dialog box, and initialise any default values
{
SetDlgItemInt(hwnd, IDC_NUMBER, 5, FALSE);
HICON hIcon, hIconSm;
hIcon = (HICON)LoadImage(NULL, "e32.ico", IMAGE_ICON, 32, 32, LR_LOADFROMFILE);
if(hIcon)
SendMessage(hwnd, WM_SETICON, ICON_BIG, (LPARAM)hIcon);
else
MessageBox(hwnd, "Could not load large icon!", "Error", MB_OK | MB_ICONERROR);
hIconSm = (HICON) LoadImage(NULL, "e16.ico", IMAGE_ICON, 16, 16, LR_LOADFROMFILE);
if(hIconSm)
SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM)hIconSm);
else
MessageBox(hwnd, "Could not load small icon!", "Error", MB_OK | MB_ICONERROR);
}
break;
case WM_COMMAND:
switch(LOWORD(wParam))
{
case IDC_START:
{
BOOL bSuccess;
int nDelay = GetDlgItemInt(hwnd, IDC_NUMBER, &bSuccess, FALSE);
nDelay= nDelay*1000;
int i=1;
ShowWindow(hwnd,SW_MINIMIZE);
if(bSuccess)
{
if (hwnd1 != 0&&hwnd2 != 0)
{
SetThreadExecutionState(ES_CONTINUOUS | ES_DISPLAY_REQUIRED);
while(i)
{
if(bDone!=TRUE)
{
SetDlgItemInt(hwnd, IDC_SHOWCOUNT, nDelay/1000, FALSE);
Sleep(nDelay);
SetForegroundWindow(hwnd1);
Sleep(nDelay);
SetForegroundWindow(hwnd2);
i++;
}
else
{
SetThreadExecutionState(ES_CONTINUOUS);
MessageBox(hwnd, "Stopped", "Warning", MB_OK);
break;
}
}
}
else
{
MessageBox(hwnd,"Cannot find suitable Window","AppDia",MB_OK);
}
}
else
{
MessageBox(hwnd, "Number not identified", "Warning", MB_OK);
}
}
break;
case IDC_STOP:
bDone==TRUE;
break;
}
break;
case WM_CLOSE:
EndDialog(hwnd, 0);
break;
default:
return FALSE;
}
return TRUE;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
return DialogBox(hInstance, MAKEINTRESOURCE(IDD_MAIN), NULL, DlgProc);
}

Answer 1

Your logic loops with Sleeps, it doesn't give the dialog box a way to process it's messages, so it seems to hang -- try using a Timer instead, with something like:
static BOOL bWnd1 = TRUE;
case WM_COMMAND:
switch(LOWORD(wParam))
{ case IDC_START:
{ int nDelay = GetDlgItemInt(hwnd, IDC_NUMBER, &bSuccess, FALSE);
nDelay= nDelay*1000;
ShowWindow(hwnd,SW_MINIMIZE);
SetTimer(hwnd, 1, nDelay, NULL);
break;
}
case IDC_STOP:
KillTimer(hwnd, 1);
break;
}
break;
case WM_TIMER:
{ HWND hwnd = (bWnd1 ? FindWindow("Notepad++",0) : FindWindow("Notepad",0));
SetForegroundWindow(hwnd);
bWnd1 = !bWnd1;
break;
}
case WM_CLOSE:
KillTimer(hwnd, 1);
EndDialog(hwnd, 0);
break;
default:
return FALSE;
This is just a sample code, you'll need to add error checking to it...