Question

我正在尝试将我的Win32应用程序封装到一个类中。当我尝试启动下面的应用程序的主窗口是我的声明和实现时出现我的问题...我注意到我的类方法InitInstance（）;

中的问题

声明

#pragma once
#include "stdafx.h"
#include "resource.h"
#define MAX_LOADSTRING 100

class RenderEngine {
protected:
    int m_width;
    int m_height;

    ATOM RegisterEngineClass();

public:
    static HINSTANCE m_hInst;
    HWND m_hWnd;
    int m_nCmdShow;
    TCHAR m_szTitle[MAX_LOADSTRING];                    // The title bar text
    TCHAR m_szWindowClass[MAX_LOADSTRING];          // the main window class name

    bool InitWindow();
    bool InitDirectX();
    bool InitInstance();

    //static functions
    static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
    static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam);

    int Run();

};

实施

#include "stdafx.h"
#include "RenderEngine.h"
HINSTANCE RenderEngine::m_hInst = NULL;

bool RenderEngine::InitWindow()
{
    RenderEngine::m_hInst = NULL;
    // Initialize global strings
    LoadString(m_hInst, IDS_APP_TITLE, m_szTitle, MAX_LOADSTRING);
    LoadString(m_hInst, IDC_RENDERENGINE, m_szWindowClass, MAX_LOADSTRING);

    if(!RegisterEngineClass())
    {
        return false;
    }

    if(!InitInstance())
    {
        return false;
    }

    return true;
}

ATOM RenderEngine::RegisterEngineClass()
{
    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = RenderEngine::WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = m_hInst;
    wcex.hIcon          = LoadIcon(m_hInst, MAKEINTRESOURCE(IDI_RENDERENGINE));
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = MAKEINTRESOURCE(IDC_RENDERENGINE);
    wcex.lpszClassName  = m_szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassEx(&wcex);
}

LRESULT CALLBACK RenderEngine::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(m_hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
            break;
        case IDM_EXIT:
            DestroyWindow(hWnd);
            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;
}

bool RenderEngine::InitInstance()
{
   m_hWnd = NULL;// When I step into my code it says on this line 0x000000 unused = ??? expression cannot be evaluated
   m_hWnd = CreateWindow(m_szWindowClass, m_szTitle, WS_OVERLAPPEDWINDOW,
       CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, m_hInst, NULL);

   if (!m_hWnd)// At this point, memory has been allocated unused = ??. It steps over this
   {
      return FALSE;
   }

   if(!ShowWindow(m_hWnd, m_nCmdShow))// m_nCmdShow = 1 and m_hWnd is still unused and expression
   {//Still cannot be evaluated. This statement is true. and shuts down.
        return false;
   }
   UpdateWindow(m_hWnd);

   return true;
}

// Message handler for about box.
INT_PTR CALLBACK RenderEngine::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;
}

int RenderEngine::Run()
{
    MSG msg;
    HACCEL hAccelTable;

    hAccelTable = LoadAccelerators(m_hInst, MAKEINTRESOURCE(IDC_RENDERENGINE));

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

    return (int) msg.wParam;
}

和我的winMain函数调用类

// RenderEngine.cpp : Defines the entry point for the application.
#include "stdafx.h"
#include "RenderEngine.h"

// Global Variables:

RenderEngine go;

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

        // TODO: Place code here.
        RenderEngine::m_hInst = hInstance;
        go.m_nCmdShow = nCmdShow;
        if(!go.InitWindow())
        {
            return 0;
        }
            go.Run();

        return 0;
    }

Answer 1

如果窗口以前不可见，则

ShowWindow会返回0，因此!ShowWindow(m_hWnd, m_nCmdShow)评估为true，导致InitInstance返回false。

对于调试器中所有这些“未使用”的东西，你是否在Debug模式下编译？

我的窗口的句柄未使用，无法评估

1 个答案: