ReOpen window from main window. - c++

Question

I have the main window open. It was created for me using visual studio. What I am attempting to do is have a main screen with 9 to 12 buttons. These buttons will then open up other windows. I am attempting with one button currently the "InventoryBtn". The inventory window open up and I am able to close it. The second time I try to open the window I get an error. It seems the window is already registered and cant be recreated. What am I doing incorrectly? I stepped thru it and aw that "Destroy:" is being called. The second time I try to show the inventory window the handle is uninitialized.
#include "stdafx.h"
#include "VehManager.h"
#include "M_Inventory.h"
#define MAX_LOADSTRING 100
#define InvWindowBtn 101
#define InvBtn 103
using namespace boost::gregorian;
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);
LRESULT CALLBACK InvWindowProcess(HWND, UINT, WPARAM, LPARAM);
HWND handleforInvWin;
WNDCLASSEX wxInv;
void CreateInventoryWindow();
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_VEHMANAGER, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE (IDC_VEHMANAGER));
MSG msg;
while (GetMessage(&msg, nullptr, 0, 0))
{
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_VEHMANAGER));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_VEHMANAGER);
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)
{
MessageBoxA(NULL, "Main window creation failed.", "904.VehicleManager", MB_OK | MB_ICONINFORMATION);
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HFONT hfDefault;
switch (message)
{
case WM_CREATE:
{
HWND hInvBtn = CreateWindowEx(NULL, L"Button", L"INVENTORY", WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
50, 220, 100, 24, hWnd, (HMENU)InvBtn, GetModuleHandle(NULL), NULL);
if (hInvBtn == NULL)
MessageBoxA(hWnd, "Could not create inventory button", "904.VehcleManager", NULL);
hfDefault = (HFONT)GetStockObject(DEFAULT_GUI_FONT);
SendMessage(hInvBtn, WM_SETFONT, (WPARAM)hfDefault, MAKELPARAM(FALSE, 0));
}
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
switch (wmId)
{
case InvBtn:
{
CreateInventoryWindow();
break;
}
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_RBUTTONDOWN:
MessageBox(NULL, L"Right button mouse clicks not allowed.", L"904.VehicleManager", NULL);
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
EndPaint(hWnd, &ps);
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
// Message handler for about box.
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 CreateInventoryWindow()
{
ZeroMemory(&wxInv, sizeof(WNDCLASSEX));
wxInv.cbClsExtra = NULL;
wxInv.cbSize = sizeof(WNDCLASSEX);
wxInv.cbWndExtra = NULL;
wxInv.hbrBackground = (HBRUSH)COLOR_WINDOW;
wxInv.hCursor = LoadCursor(NULL, IDC_ARROW);
wxInv.hIcon = NULL;
wxInv.hIconSm = NULL;
wxInv.hInstance = hInst;
wxInv.lpfnWndProc = (WNDPROC)InvWindowProcess;
wxInv.lpszClassName = L"Inventory";
wxInv.lpszMenuName = NULL;
wxInv.style = CS_HREDRAW | CS_VREDRAW;
if (!RegisterClassEx(&wxInv))
{
int nResult = GetLastError();
MessageBox(NULL, L"Inventory window class registration failed.", L"904.VehicleManager", MB_ICONEXCLAMATION);
return;
}
handleforInvWin = CreateWindowEx(NULL, wxInv.lpszClassName, L"Open Window 2", WS_OVERLAPPEDWINDOW,
200, 170, 640, 480, NULL, NULL, hInst, NULL);
if (!handleforInvWin)
{
MessageBox(NULL, L"Error with the inventory window handle.", L"904.VehManager", MB_ICONEXCLAMATION);
return;
}
ShowWindow(handleforInvWin, SW_SHOWNOACTIVATE);
UpdateWindow(handleforInvWin);
}
LRESULT CALLBACK InvWindowProcess(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HFONT hfDefault;
switch (message)
{
case WM_CREATE:
{
HWND hInvBtn = CreateWindowEx(NULL, L"Button", L"Close", WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
50, 220, 100, 24, hwnd, (HMENU)InvBtn, GetModuleHandle(NULL), NULL);
if (hInvBtn == NULL)
MessageBoxA(hwnd, "Could not create inventory button", "904.VehcleManager", NULL);
hfDefault = (HFONT)GetStockObject(DEFAULT_GUI_FONT);
SendMessage(hInvBtn, WM_SETFONT, (WPARAM)hfDefault, MAKELPARAM(FALSE, 0));
break;
}
case WM_DESTROY:
{
break;
}
case WM_COMMAND:
case InvBtn:
{
DestroyWindow(hwnd);
break;
}
break;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}