如何处理按钮按下（桌面应用程序）

Question

我正在制作一个桌面应用程序，我让它显示一个按钮。现在我想做的是以某种方式处理按钮按下，但我不知道如何处理。到目前为止，这是我的代码：

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

// Global variables

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

// The string that appears in the application's title bar.
static TCHAR szTitle[] = _T("First Desktop Application");

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 + 1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance, IDI_APPLICATION);

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(NULL,
            _T("Call to RegisterClassEx failed!"),
            _T("Windows Desktop Guided Tour"),
            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,
        500, 500,
        NULL,
        NULL,
        hInstance,
        NULL
    );
    HWND hwndButton = CreateWindow(
        L"BUTTON",  // Predefined class; Unicode assumed 
        L"Test2",      // Button text 
        WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,  // Styles 
        10,         // x position 
        100,         // y position 
        100,        // Button width
        20,        // Button height
        hWnd,     // Parent window
        NULL,       // No menu.
        (HINSTANCE)GetWindowLongPtr(hWnd, GWLP_HINSTANCE),
        NULL);

    if (!hWnd)
    {
        MessageBox(NULL,
            _T("Call to CreateWindow failed!"),
            _T("Windows Desktop Guided Tour"),
            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("Test");

    switch (message)
    {
    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;
}

这是一个 Windows 桌面向导项目，于 Visual Studio 2019 年完成。我只想让它做一些简单的事情，比如在屏幕上显示一些文本或按下按钮时的其他内容。

这就是 window 的样子：

Answer 1

单击 BUTTON 时，它会向其父级 window 发送 BN_CLICKED 通知消息。您只需在 WndProc() 中处理该消息，例如：

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
        ...

        case WM_COMMAND:
        {
            if (HIWORD(wParam) == BN_CLICKED)
            {
                // LOWORD(wParam) is the button's ID
                // HWND(lParam) is the button's HWND
                // do something with them as needed...
                return 0;
            }
            break;
        }

        ...
    }

    return DefWindowProc(hWnd, message, wParam, lParam);
}

这在 MSDN 的 BUTTON documentation 中有解释：

Button Messages

Handling Messages from a Button

Notifications from a button are sent as either WM_COMMAND or WM_NOTIFY messages. Information about which message is used can be found on the reference page for each notification.

For more information on how to handle messages, see Control Messages. See also Button Messages.

Notification Messages from Buttons

When the user clicks a button, its state changes, and the button sends notification codes, in the form of WM_COMMAND messages, to its parent window. For example, a push button control sends the BN_CLICKED notification code whenever the user chooses the button. In all cases (except for BCN_HOTITEMCHANGE), the low-order word of the wParam parameter contains the control identifier, the high-order word of wParam contains the notification code, and the lParam parameter contains the control window handle.

如何处理按钮按下（桌面应用程序）

How to handle a button press (Desktop Application)

c++

winapi

desktop-application

button

Handling Messages from a Button

Notification Messages from Buttons