Question

我正在尝试使用WinAPi创建简单的Windows应用程序。这是代码：

       #include "stdafx.h"
       #include "APIup.h"

       #define MAX_LOADSTRING 100
       HWND hWnd,cw13;
       // Global Variables:
       HINSTANCE hInst;                             // current                      instance
       TCHAR szTitle[MAX_LOADSTRING];                   // The title bar text
       TCHAR szWindowClass[MAX_LOADSTRING];         // the main window class name

       // Forward declarations of functions included in this code module:
       ATOM             MyRegisterClass(HINSTANCE hInstance);
       ATOM Register(HINSTANCE hInstance);
       BOOL             InitInstance(HINSTANCE, int);
       LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
       LRESULT CALLBACK    WndProc_dla13(HWND, UINT, WPARAM, LPARAM);
       INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);

       int APIENTRY _tWinMain(HINSTANCE hInstance,
                            HINSTANCE hPrevInstance,
                            LPTSTR    lpCmdLine,
                            int       nCmdShow)
       {
        UNREFERENCED_PARAMETER(hPrevInstance);
        UNREFERENCED_PARAMETER(lpCmdLine);

            // TODO: Place code here.
        MSG msg;
                HACCEL hAccelTable;

        // Initialize global strings
        LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
        LoadString(hInstance, IDC_APIUP, szWindowClass, MAX_LOADSTRING);
        MyRegisterClass(hInstance);
        Register(hInstance);

        // Perform application initialization:
        if (!InitInstance (hInstance, nCmdShow))
        {
            return FALSE;
        }

        hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_APIUP));

        // Main message loop:
        while (GetMessage(&msg, NULL, 0, 0))
        {
            if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
        }

        return (int) msg.wParam;
       }





        ATOM MyRegisterClass(HINSTANCE hInstance)
        {
            WNDCLASSEX 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_APIUP));
            wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
            wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
            wcex.lpszMenuName   = MAKEINTRESOURCE(IDC_APIUP);
            wcex.lpszClassName  = szWindowClass;
            wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));


            return RegisterClassEx(&wcex);
               }

               ATOM Register(HINSTANCE hInstance)
               {
            WNDCLASSEX cw13class;

            cw13class.cbSize = sizeof(WNDCLASSEX);

            cw13class.style         = CS_HREDRAW | CS_VREDRAW;
            cw13class.lpfnWndProc   = WndProc_dla13;
            cw13class.cbClsExtra        = 0;
            cw13class.cbWndExtra        = 0;
            cw13class.hInstance     = hInstance;
            cw13class.hIcon         = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APIUP));
            cw13class.hCursor       = LoadCursor(NULL, IDC_ARROW);
            cw13class.hbrBackground = GetSysColorBrush(COLOR_3DFACE);
            cw13class.lpszMenuName  = NULL;
            cw13class.lpszClassName = L"13class";
            cw13class.hIconSm       = LoadIcon(cw13class.hInstance,                               MAKEINTRESOURCE(IDI_SMALL));
            return RegisterClassEx(&cw13class);

        }

        BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
        {




           hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
              CW_USEDEFAULT, 0, 100, 100, NULL, NULL, hInstance, NULL);
           cw13=CreateWindow(L"13class",L"Ćwiczenie                         13",WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,0,300,300,NULL,NULL,hInst,NULL);


           if (!hWnd)
           {
              return FALSE;
           }

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

           return TRUE;
        }


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    PAINTSTRUCT ps;
    HDC hdc;

    switch (message)
    {
    case WM_COMMAND:
        wmId    = LOWORD(wParam);
        wmEvent = HIWORD(wParam);
        // Parse the menu selections:

        switch (wmId)
        {
        case IDM_ABOUT:
            DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
            break;
        case IDM_EXIT:
            DestroyWindow(hWnd);
            break;
        case ID_32771:
            ShowWindow(cw13, 1);
            break;

        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
        }
        break;
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        // TODO: Add any drawing code here...
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

LRESULT CALLBACK WndProc_dla13 (HWND hWnd, UINT msg/*message*/, WPARAM  wParam,LPARAM lParam)
        {
 switch(msg)  
  {
    case WM_CREATE:

      CreateWindowW(L"button", L"Beep",
          WS_VISIBLE | WS_CHILD ,
          20, 50, 80, 25,
          cw13, (HMENU) 1, hInst, NULL);

      CreateWindowW(L"button", L"Quit",
          WS_VISIBLE | WS_CHILD ,
          120, 50, 80, 25,
          cw13, (HMENU) 2, NULL, NULL);
      break;

    case WM_COMMAND:

      if (LOWORD(wParam) == 1) {
        Beep(40, 50);
      }

      if (LOWORD(wParam) == 2) {
        PostQuitMessage(0);
      }

      break;

    case WM_DESTROY:

      PostQuitMessage(0);
      break;
      default:
        return DefWindowProc(hWnd, msg, 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;
}

问题在于：当我创建窗口'cw13'时，它会被创建并显示，但按钮不是。我创建了两个单独的WndProc函数。其他消息正确执行（例如WM_QUIT），CreateWindowW下只有WM_CREATE，女巫应该创建并显示按钮不是。问题出在哪儿？

Answer 1

处理WM_CREATE消息时，您对CreateWindow(L"13class")的呼叫仍在运行。您的cw13变量尚未分配，因此您指定的无效HWND作为按钮的父级。这就是他们没有出现的原因。使用hwnd的{{1}}参数代替父级。这将是WndProc_dla13()在HWND退出后分配给cw13变量的CreateWindow(L"13class")。

WinApi，按钮不显示

1 个答案: