使用C++在VS2019中制作一个GUI来展示倒计时的完整代码

以下是使用C++和MFC库在VS2019中制作倒计时GUI的完整代码：

// CountdownTimerDlg.h

#pragma once

#include "afxwin.h"

class CCountdownTimerDlg : public CDialogEx
{
public:
    CCountdownTimerDlg(CWnd* pParent = nullptr);   // standard constructor
    virtual ~CCountdownTimerDlg();

// Dialog Data
#ifdef AFX_DESIGN_TIME
    enum { IDD = IDD_COUNTDOWN_TIMER_DIALOG };
#endif

protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

    DECLARE_MESSAGE_MAP()

private:
    int m_hours;
    int m_minutes;
    int m_seconds;

    CStatic m_display;

    bool m_timer_running;
    UINT_PTR m_timer_id;

    void UpdateDisplay();

public:
    virtual BOOL OnInitDialog();
    afx_msg void OnBnClickedStartButton();
    afx_msg void OnBnClickedStopButton();
    afx_msg void OnTimer(UINT_PTR nIDEvent);
};

// CountdownTimerDlg.cpp

#include "stdafx.h"
#include "CountdownTimer.h"
#include "CountdownTimerDlg.h"
#include "afxdialogex.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// CCountdownTimerDlg dialog

CCountdownTimerDlg::CCountdownTimerDlg(CWnd* pParent /*=nullptr*/)
    : CDialogEx(IDD_COUNTDOWN_TIMER_DIALOG, pParent),
    m_hours(0), m_minutes(0), m_seconds(0), m_timer_running(false), m_timer_id(0)
{
}

CCountdownTimerDlg::~CCountdownTimerDlg()
{
}

void CCountdownTimerDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialogEx::DoDataExchange(pDX);
    DDX_Control(pDX, IDC_DISPLAY, m_display);
}

BEGIN_MESSAGE_MAP(CCountdownTimerDlg, CDialogEx)
    ON_BN_CLICKED(IDC_START_BUTTON, &CCountdownTimerDlg::OnBnClickedStartButton)
    ON_BN_CLICKED(IDC_STOP_BUTTON, &CCountdownTimerDlg::OnBnClickedStopButton)
    ON_WM_TIMER()
END_MESSAGE_MAP()

// CCountdownTimerDlg message handlers

BOOL CCountdownTimerDlg::OnInitDialog()
{
    CDialogEx::OnInitDialog();

    // Set the timer interval to 1 second
    SetTimer(m_timer_id, 1000, NULL);

    return TRUE;
}

void CCountdownTimerDlg::OnBnClickedStartButton()
{
    // Get the user input for hours, minutes, and seconds
    m_hours = GetDlgItemInt(IDC_HOURS_EDIT);
    m_minutes = GetDlgItemInt(IDC_MINUTES_EDIT);
    m_seconds = GetDlgItemInt(IDC_SECONDS_EDIT);

    // Start the timer
    m_timer_running = true;
}

void CCountdownTimerDlg::OnBnClickedStopButton()
{
    // Stop the timer
    m_timer_running = false;
}

void CCountdownTimerDlg::OnTimer(UINT_PTR nIDEvent)
{
    if (m_timer_running)
    {
        // Decrement the remaining time
        if (m_seconds > 0)
        {
            m_seconds--;
        }
        else if (m_minutes > 0)
        {
            m_minutes--;
            m_seconds = 59;
        }
        else if (m_hours > 0)
        {
            m_hours--;
            m_minutes = 59;
            m_seconds = 59;
        }
        else
        {
            // Time's up!
            m_timer_running = false;
        }

        UpdateDisplay();
    }

    CDialogEx::OnTimer(nIDEvent);
}

void CCountdownTimerDlg::UpdateDisplay()
{
    CString display_text;
    display_text.Format(_T("%02d:%02d:%02d"), m_hours, m_minutes, m_seconds);
    m_display.SetWindowText(display_text);
}

在这个代码中，我们创建了一个名为CCountdownTimerDlg的对话框类。在OnInitDialog函数中，我们设置了定时器间隔为1秒，并在OnTimer函数中处理了倒计时逻辑。用户通过在编辑框中输入小时、分钟、秒数来指定倒计时时间，并通过点击开始和停止按钮来启动和停止倒计时。最后，我们在UpdateDisplay函数中更新了GUI中的显示内容。