[CSHARP] How to Capture System Events

Xin chào các bạn, bài viết hôm nay mình sẽ tiếp tục hướng dẫn các bạn cách bắt sự kiện Windows System trên lập trình C#, Winform.

[C#] Lắng nghe sự kiện System Event Windows trên winform

Microsoft cung cấp cho chúng ta một class để chúng ta sử dụng để bắt sự kiện trên Windows: Microsoft.Win32.SystemEvents

Giao diện demo ứng dụng C#:

Ở hình trên, các bạn thấy khi mình thay đổi: Độ phân giải màn hình, ngày giờ hệ thống... thì nó bắt sự kiện và show ra cho mình biết.

Dưới đây, là các sự kiện của lớp SystemEvents:

Name	Description
DisplaySettingsChanged	Occurs when the user changes the display settings.
DisplaySettingsChanging	Occurs when the display settings are changing.
EventsThreadShutdown	Occurs before the thread that listens for system events is terminated.
InstalledFontsChanged	Occurs when the user adds fonts to or removes fonts from the system.
LowMemory	Obsolete. Occurs when the system is running out of available RAM.
PaletteChanged	Occurs when the user switches to an application that uses a different palette.
PowerModeChanged	Occurs when the user suspends or resumes the system.
SessionEnded	Occurs when the user is logging off or shutting down the system.
SessionEnding	Occurs when the user is trying to log off or shut down the system.
SessionSwitch	Occurs when the currently logged-in user has changed.
TimeChanged	Occurs when the user changes the time on the system clock.
TimerElapsed	Occurs when a windows timer interval has expired.
UserPreferenceChanged	Occurs when a user preference has changed.
UserPreferenceChanging	Occurs when a user preference is changing.

Full source code C#:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SystemEventListener
{
    public partial class Form1 : Form
    {
        private bool eventHandlersCreated;
        public Form1()
        {
            InitializeComponent();
        }

        private void btnListen_Click(object sender, EventArgs e)
        {
            this.StartListening();
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            this.StopListening();
        }

        private void StartListening()
        {
            Microsoft.Win32.SystemEvents.InstalledFontsChanged += new EventHandler(FontHandler);
            Microsoft.Win32.SystemEvents.DisplaySettingsChanged += new EventHandler(ScreenHandler);
            Microsoft.Win32.SystemEvents.TimeChanged += new EventHandler(TimeHandler);
            Microsoft.Win32.SystemEvents.UserPreferenceChanged += new Microsoft.Win32.UserPreferenceChangedEventHandler(PreferenceChangedHandler);

            this.eventHandlersCreated = true;
        }

        private void StopListening()
        {
            Microsoft.Win32.SystemEvents.InstalledFontsChanged -= new EventHandler(FontHandler);
            Microsoft.Win32.SystemEvents.DisplaySettingsChanged -= new EventHandler(ScreenHandler);
            Microsoft.Win32.SystemEvents.TimeChanged -= new EventHandler(TimeHandler);
            Microsoft.Win32.SystemEvents.UserPreferenceChanged -= new Microsoft.Win32.UserPreferenceChangedEventHandler(PreferenceChangedHandler);

            this.eventHandlersCreated = false;
        }

        private void FontHandler(object sender, EventArgs e)
        {
            txtLog.Text += string.Format("Installed fonts changed. {0}", Environment.NewLine);
        }

        private void PreferenceChangedHandler(object sender, Microsoft.Win32.UserPreferenceChangedEventArgs e)
        {
            txtLog.Text += string.Format("You changed a setting: {0} {1}", e.Category.ToString(), Environment.NewLine);
        }

        private void ScreenHandler(object sender, EventArgs e)
        {
            txtLog.Text += string.Format("Screen resolution changed. {0}", Environment.NewLine);
        }

        private void TimeHandler(object sender, EventArgs e)
        {
            txtLog.Text += string.Format("System time changed. {0}", Environment.NewLine);
        }
    }
}

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