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Fix GDI resource leaks, disposal pattern, and minor code quality improvements #1

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6cff8ba
Initial plan
Copilot Mar 14, 2026
ed1923b
Improve code quality: fix resource leaks, disposal, SYSKEYDOWN, nulla…
Copilot Mar 14, 2026
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5 changes: 3 additions & 2 deletions GlobalKeyLogger/GlobalKeyLogger.csproj
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<OutputType>WinExe</OutputType>
Expand All @@ -7,7 +7,8 @@
<RuntimeIdentifier>win-x64</RuntimeIdentifier>
<SelfContained>true</SelfContained>
<PublishSingleFile>true</PublishSingleFile>
<PublishTrimmed>false</PublishTrimmed> <!-- Optional, don't trim if you don't want to risk issues -->
<PublishTrimmed>false</PublishTrimmed>
<Nullable>enable</Nullable>
</PropertyGroup>


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152 changes: 87 additions & 65 deletions GlobalKeyLogger/Program.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
using System;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
Expand All @@ -8,48 +8,64 @@

class GlobalKeyLogger : ApplicationContext
{
private static Stopwatch stopwatch = Stopwatch.StartNew();
private static StreamWriter writer;
private static readonly Stopwatch stopwatch = Stopwatch.StartNew();
private static StreamWriter? writer;
private static long lastKeyDownTime = 0;
private static bool firstKey = true;
private static long flightTime = -1;
private static IntPtr _hookID = IntPtr.Zero;
private static Dictionary<int, long> keyDownTimes = new Dictionary<int, long>();
private static NotifyIcon trayIcon;
private static readonly Dictionary<int, long> keyDownTimes = new Dictionary<int, long>();
private static NotifyIcon? trayIcon;
private static bool isRecording = true;
private static Icon recordIcon;
private static Icon pauseIcon;
private static string logFileName;
private static int keystrokeCount = 0; // 🆕 Track number of logged keystrokes
private static Icon? recordIcon;
private static Icon? pauseIcon;
private static string logFileName = string.Empty;
private static int keystrokeCount = 0;
private bool _disposed = false;

private static LowLevelKeyboardProc _proc = HookCallback;
private static readonly LowLevelKeyboardProc _proc = HookCallback;

public GlobalKeyLogger()
{
// Load icons
recordIcon = CreateRedDotIcon();
pauseIcon = CreatePauseIcon();

// Create tray icon
trayIcon = new NotifyIcon()
{
Icon = recordIcon,
Visible = true,
Text = "Global Keylogger (0)" // Initial tooltip
Text = "Global Keylogger (0)"
};

// Create context menu
trayIcon.ContextMenuStrip = new ContextMenuStrip();
trayIcon.ContextMenuStrip.Items.Add("Pause", null, PauseLogging);
trayIcon.ContextMenuStrip.Items.Add("Exit", null, Exit);

trayIcon.DoubleClick += TrayIcon_DoubleClick;

// Setup keylogger
CreateNewLogFile();
_hookID = SetHook(_proc);
}

protected override void Dispose(bool disposing)
{
if (_disposed) return;
_disposed = true;
if (disposing)
{
if (_hookID != IntPtr.Zero)
{
UnhookWindowsHookEx(_hookID);
_hookID = IntPtr.Zero;
}
writer?.Dispose();
trayIcon?.Dispose();
recordIcon?.Dispose();
pauseIcon?.Dispose();
}
base.Dispose(disposing);
}

private void CreateNewLogFile()
{
string timestamp = DateTime.Now.ToString("yyyy-MM-dd_HH-mm-ss");
Expand All @@ -60,81 +76,75 @@ private void CreateNewLogFile()
writer.Flush();
}

private void TrayIcon_DoubleClick(object sender, EventArgs e)
private void TrayIcon_DoubleClick(object? sender, EventArgs e)
{
MessageBox.Show($"Keylogger is {(isRecording ? "recording" : "paused")}.\nLogged {keystrokeCount} keystrokes.\n\nLogging to:\n{logFileName}\n\nRight-click tray icon for options.", "Global Keylogger");
MessageBox.Show(
$"Keylogger is {(isRecording ? "recording" : "paused")}.\nLogged {keystrokeCount} keystrokes.\n\nLogging to:\n{logFileName}\n\nRight-click tray icon for options.",
"Global Keylogger");
}

private void PauseLogging(object sender, EventArgs e)
private void PauseLogging(object? sender, EventArgs e)
{
isRecording = !isRecording;
trayIcon.Icon = isRecording ? recordIcon : pauseIcon;
trayIcon.ContextMenuStrip.Items[0].Text = isRecording ? "Pause" : "Resume";
UpdateTooltip(); // 🆕 Update tooltip on pause/resume
trayIcon!.Icon = isRecording ? recordIcon : pauseIcon;
trayIcon.ContextMenuStrip!.Items[0].Text = isRecording ? "Pause" : "Resume";
UpdateTooltip();
}

private void Exit(object sender, EventArgs e)
private void Exit(object? sender, EventArgs e)
{
trayIcon.Visible = false;
writer?.Close();
UnhookWindowsHookEx(_hookID);
trayIcon!.Visible = false;
Dispose();
Application.Exit();
}

private static IntPtr SetHook(LowLevelKeyboardProc proc)
{
using (Process curProcess = Process.GetCurrentProcess())
using (ProcessModule curModule = curProcess.MainModule!)
{
return SetWindowsHookEx(WH_KEYBOARD_LL, proc,
GetModuleHandle(curModule.ModuleName), 0);
}
using Process curProcess = Process.GetCurrentProcess();
using ProcessModule curModule = curProcess.MainModule!;
return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
}

private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
if (nCode >= 0)
if (nCode >= 0 && writer != null && isRecording)
{
int vkCode = Marshal.ReadInt32(lParam);

if (isRecording)
if (wParam == (IntPtr)WM_KEYDOWN || wParam == (IntPtr)WM_SYSKEYDOWN)
{
if (wParam == (IntPtr)WM_KEYDOWN)
{
long currDownTime = stopwatch.ElapsedMilliseconds;
long currDownTime = stopwatch.ElapsedMilliseconds;

if (firstKey)
{
if (firstKey)
{
flightTime = -1;
firstKey = false;
}
else
{
flightTime = currDownTime - lastKeyDownTime;
if (flightTime > 1500)
flightTime = -1;
firstKey = false;
}
else
{
flightTime = currDownTime - lastKeyDownTime;
if (flightTime > 1500)
flightTime = -1;
}

lastKeyDownTime = currDownTime;
keyDownTimes[vkCode] = currDownTime;
}
else if (wParam == (IntPtr)WM_KEYUP)

lastKeyDownTime = currDownTime;
keyDownTimes[vkCode] = currDownTime;
}
else if (wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP)
{
if (keyDownTimes.TryGetValue(vkCode, out long downTime))
{
if (keyDownTimes.TryGetValue(vkCode, out long downTime))
{
long releaseTime = stopwatch.ElapsedMilliseconds;
long holdTime = releaseTime - downTime;
long holdTime = stopwatch.ElapsedMilliseconds - downTime;

writer.WriteLine($"{vkCode},{holdTime},{flightTime}");
writer.Flush();
writer.WriteLine($"{vkCode},{holdTime},{flightTime}");
writer.Flush();

keystrokeCount++; // 🆕 Count each logged key
UpdateTooltip(); // 🆕 Update tray text
keystrokeCount++;
UpdateTooltip();

keyDownTimes.Remove(vkCode);
}
keyDownTimes.Remove(vkCode);
}
}
}
Expand All @@ -145,35 +155,43 @@ private static void UpdateTooltip()
{
string state = isRecording ? "Recording" : "Paused";
string tooltip = $"Keylogger ({state})\nKeys: {keystrokeCount}";
trayIcon.Text = tooltip.Length > 63 ? tooltip.Substring(0, 63) : tooltip;
trayIcon!.Text = tooltip.Length > 63 ? tooltip.Substring(0, 63) : tooltip;
}

private static Icon CreateRedDotIcon()
{
Bitmap bmp = new Bitmap(16, 16);
using Bitmap bmp = new Bitmap(16, 16);
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clear(Color.Transparent);
g.FillEllipse(Brushes.Red, 2, 2, 12, 12);
}
return Icon.FromHandle(bmp.GetHicon());
IntPtr hIcon = bmp.GetHicon();
Icon icon = (Icon)Icon.FromHandle(hIcon).Clone();
DestroyIcon(hIcon);
return icon;
}

private static Icon CreatePauseIcon()
{
Bitmap bmp = new Bitmap(16, 16);
using Bitmap bmp = new Bitmap(16, 16);
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clear(Color.Transparent);
g.FillRectangle(Brushes.RoyalBlue, 4, 2, 3, 12);
g.FillRectangle(Brushes.RoyalBlue, 9, 2, 3, 12);
}
return Icon.FromHandle(bmp.GetHicon());
IntPtr hIcon = bmp.GetHicon();
Icon icon = (Icon)Icon.FromHandle(hIcon).Clone();
DestroyIcon(hIcon);
return icon;
}

private const int WH_KEYBOARD_LL = 13;
private const int WM_KEYDOWN = 0x0100;
private const int WM_KEYUP = 0x0101;
private const int WM_SYSKEYDOWN = 0x0104;
private const int WM_SYSKEYUP = 0x0105;

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetWindowsHookEx(int idHook,
Expand All @@ -190,6 +208,10 @@ private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetModuleHandle(string lpModuleName);

[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool DestroyIcon(IntPtr hIcon);

[STAThread]
static void Main()
{
Expand Down