winapi - (c++ win32) Window not showing up despite it running

Question

I was trying to subclass a button but my window isn't showing up and I have to restart visual studio every time to run the application. At the moment nothing shows up : it just shows nothing when I run the application. I think it's something to do with the function RegisterClass1.Please help

Here is my code:

// CustomButton.cpp : Defines the entry point for the application.
//

#include "framework.h"
#include "CustomButton.h"
#include "SkinClass/skin.h"
#include <commctrl.h>
#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;                                // current instance
WCHAR szTitle[MAX_LOADSTRING];                  // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING];            // the main window class name
const char g_szClassName[] = "MyClassName";

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);
void                RegisterClass1(HINSTANCE);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: Place code here.

    // Initialize global strings
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_CUSTOMBUTTON, szWindowClass, MAX_LOADSTRING);
    //MyRegisterClass(hInstance);
    RegisterClass1(hInstance);










    // Perform application initialization:
    /*if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }*/
    /*HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);*/

    HWND hWnd = CreateWindowExA(WS_EX_LAYERED, g_szClassName, "Scenes", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL,
        hInstance, NULL);



    CSkin aa(IDR_CR, ID_CIRCLE);
    RECT rect;
    GetWindowRect(hWnd, &rect);

    HWND hButton = CreateWindow(TEXT("BUTTON"), TEXT("START EDITING!"), WS_CHILD | WS_VISIBLE | BS_OWNERDRAW, ((rect.right - rect.left) / 2) - 90, 500, aa.Width(), aa.Height(),
        hWnd, (HMENU)NULL, NULL, NULL);




    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_CUSTOMBUTTON));





    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);










    MSG msg;

    // Main message loop:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
    aa.Destroy();
    return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
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_CUSTOMBUTTON));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = MAKEINTRESOURCEW(IDC_CUSTOMBUTTON);
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   FUNCTION: RegisterClass1()
//
//   PURPOSE: Registers the class
//
//   COMMENTS:
//
//
//
//

void RegisterClass1(HINSTANCE hInstance) {
    WNDCLASSEXA wc;
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wc.hInstance = hInstance;
    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = g_szClassName;
    wc.lpszMenuName = "MENU";
    wc.style = CS_HREDRAW | CS_VREDRAW;


}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   hInst = hInstance; // Store instance handle in our global variable

   HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

LRESULT CALLBACK ButtonProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
    switch (Msg)
    {
    case WM_PAINT: {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hWnd, &ps);
        HDC hdc_x = CreateCompatibleDC(0);
        HINSTANCE hInstance = GetModuleHandle(NULL);
        HBITMAP hBitmap = (HBITMAP)LoadBitmap(hInstance, MAKEINTRESOURCE(ID_CIRCLE)); //Load the bitmap
        HBITMAP holdbmp;
        holdbmp=(HBITMAP)SelectObject(hdc_x, hBitmap); //Put the bitmap into the hdc_x
        SelectObject(hdc_x, holdbmp);
        BitBlt(hdc, 0, 0, 180, 50, hdc_x, 0, 0, SRCCOPY); //Draw it.
        EndPaint(hWnd, &ps);
        DeleteObject(hBitmap);
        DeleteDC(hdc_x);
        break;
    }

    default:
        return DefSubclassProc(hWnd, Msg, wParam, lParam);
    }
    return 0;
}
















//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE: Processes messages for the main window.
//
//  WM_COMMAND  - process the application menu
//  WM_PAINT    - Paint the main window
//  WM_DESTROY  - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_CREATE:

    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // Parse the menu selections:
            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);
            // TODO: Add any drawing code that uses hdc here...
            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;
}

If I don't restart the laptop, visual studio gives me this message : Error LNK1168 cannot open C:UsersRubelsource eposCustomButtonDebugCustomButton.exe for writing CustomButton C:UsersRubelsource eposCustomButtonCustomButtonLINK 1

Answer 1

Based on the "Layered Windows":

After the CreateWindowEx call, the layered window will not become visible until the SetLayeredWindowAttributes or UpdateLayeredWindow function has been called for this window.

The following is an example to make the layered window visible (show up):

   HWND hWnd = CreateWindowExA(WS_EX_LAYERED, g_szClassName, "Scenes", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL,
       hInstance, NULL);

   SetLayeredWindowAttributes(hWnd, NULL, 255, LWA_ALPHA);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

Update:

Another cause for this issue is RegisterClassExW is not called (in RegisterClass1), this will cause CreateWindow fails with returning NULL window handle. So error checking is very important.