在 Win32 桌面应用程序上创建按钮时出错

Question

我正在尝试在我的 Windows32 桌面应用程序的主 window 上创建一个按钮，但是当我运行它时， window 显示“你好， Windows 桌面！"但按钮不显示，我不确定为什么。我认为问题出在“HWND hwndButton = CreateWindow”，但我不确定问题是什么或我可能遗漏了什么。我的代码如下所示：

#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <tchar.h>

#define IDC_BUTTON                  3456

// Global variables

// The main window class name.
static TCHAR szWindowClass[] = _T("CD_ROM_READER_APP");

// The string that appears in the application's title bar.
static TCHAR szTitle[] = _T("CD Rom Reader App");

HINSTANCE hInst;

// Forward declarations of functions included in this code module:
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int CALLBACK WinMain(
    _In_ HINSTANCE hInstance,
    _In_opt_ HINSTANCE hPrevInstance,
    _In_ LPSTR     lpCmdLine,
    _In_ int       nCmdShow
)
{
    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, IDI_APPLICATION);
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 2);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance, IDI_APPLICATION);

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(NULL,
            _T("Call to RegisterClassEx failed!"),
            _T("CD Rom Reader App"),
            NULL);

        return 1;
    }

    // Store instance handle in our global variable
    hInst = hInstance;

    // The parameters to CreateWindow explained:
    // szWindowClass: the name of the application
    // szTitle: the text that appears in the title bar
    // WS_OVERLAPPEDWINDOW: the type of window to create
    // CW_USEDEFAULT, CW_USEDEFAULT: initial position (x, y)
    // 500, 100: initial size (width, length)
    // NULL: the parent of this window
    // NULL: this application does not have a menu bar
    // hInstance: the first parameter from WinMain
    // NULL: not used in this application
    HWND hWnd = CreateWindow(
        szWindowClass,
        szTitle,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        1000, 500,
        NULL,
        NULL,
        hInstance,
        NULL
    );

    if (!hWnd)
    {
        MessageBox(NULL,
            _T("Call to CreateWindow failed!"),
            _T("CD Rom Reader App"),
            NULL);

        return 1;
    }

    // The parameters to ShowWindow explained:
    // hWnd: the value returned from CreateWindow
    // nCmdShow: the fourth parameter from WinMain
    ShowWindow(hWnd,
        nCmdShow);
    UpdateWindow(hWnd);

    // Main message loop:
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  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)
{
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR greeting[] = _T("Hello, Windows desktop!");

    switch (message)
    {
    case WM_CREATE:
        return 0;

    case WM_COMMAND:
    {
        switch (LOWORD(wParam))
        {
            case IDC_BUTTON:
            
                HWND hwndButton = CreateWindow(
                L"BUTTON",  // Predefined class; Unicode assumed 
                L"OK",      // Button text 
                WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
                10,         // x position 
                10,         // y position 
                100,        // Button width
                100,        // Button height
                hWnd,     // Parent window
                NULL,       // No menu.
                (HINSTANCE)GetWindowLongPtr(hWnd, GWLP_HINSTANCE),
                NULL);      // Pointer not needed.

                //do whatever you want to do here when button is pressed
                break;
        }
    }
    break;


    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);

        // Here your application is laid out.
        // For this introduction, we just print out "Hello, Windows desktop!"
        // in the top left corner.
        TextOut(hdc,
            5, 5,
            greeting, _tcslen(greeting));
        // End application-specific layout section.

        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return 0;
}

Answer 1

你应该在WM_CREATE（或main函数）中创建一个按钮，并传递HMENU参数，然后使用WM_COMMAND处理按钮按下功能。

您可以参考以下代码：

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR greeting[] = _T("Hello, Windows desktop!");

    switch (message)
    {
    case WM_CREATE:
    {
        HWND hwndButton = CreateWindow(
            L"BUTTON",  // Predefined class; Unicode assumed 
            L"OK",      // Button text 
            WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
            10,         // x position 
            10,         // y position 
            100,        // Button width
            100,        // Button height
            hWnd,     // Parent window
            (HMENU)IDC_BUTTON,       // No menu.
            (HINSTANCE)GetWindowLongPtr(hWnd, GWLP_HINSTANCE),
            NULL);      // Pointer not needed.
        return 0;
    }
    case WM_COMMAND:
    {
        switch (LOWORD(wParam))
        {
        case IDC_BUTTON:
            //do whatever you want to do here when button is pressed
            //like
            MessageBox(NULL,L"hello windows", L"title", 0);
        }
    }
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);

        // Here your application is laid out.
        // For this introduction, we just print out "Hello, Windows desktop!"
        // in the top left corner.
        TextOut(hdc,
            5, 5,
            greeting, _tcslen(greeting));
        // End application-specific layout section.

        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return 0;
}

在 Win32 桌面应用程序上创建按钮时出错

Error Creating a button on Win32 Desktop App

c++

user-interface

winapi

desktop

button