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How to record while the window is not active?

I am making a recorder that records a specific window the user chooses. While I am recording, the program forces the window to be active all the time. It does not let me minimize it or even move it. It forced me to use alt + f4(that kills the active window) because I was not able to stop the recording. Is there a way to fix that?
Combobox code:
private void Handlebox_SelectedIndexChanged(object sender, EventArgs e)
{
if (Handlebox.SelectedIndex == 0)
{
handle_name = Handlebox.Items[0].ToString();
}
else if (Handlebox.SelectedIndex == 1)
{
handle_name = Handlebox.Items[1].ToString();
}
else if (Handlebox.SelectedIndex == 2)
{
handle_name = Handlebox.Items[2].ToString();
}
else if (Handlebox.SelectedIndex == 3)
{
handle_name = Handlebox.Items[3].ToString();
}
else if (Handlebox.SelectedIndex == 4)
{
handle_name = Handlebox.Items[4].ToString();
}
else if (Handlebox.SelectedIndex == 5)
{
handle_name = Handlebox.Items[5].ToString();
}
}
The way I add all the processes in the combobox:
foreach (Process process in processlist)
{
if (!String.IsNullOrEmpty(process.MainWindowTitle))
{
Handlebox.Items.Add(process.ProcessName);
}
}
The script that the whole recording takes place:
// Record video:
[StructLayout(LayoutKind.Sequential)]
public struct Rect
{
public int left;
public int top;
public int right;
public int bottom;
}
[DllImport("user32.dll")]
private static extern int SetForegroundWindow(IntPtr hWnd);
private const int SW_RESTORE = 9;
[DllImport("user32.dll")]
private static extern IntPtr ShowWindow(IntPtr hWnd, int nCmdShow);
[DllImport("user32.dll")]
public static extern IntPtr GetWindowRect(IntPtr hWnd, ref Rect rect);
public Bitmap CaptureApplication(string procName)
{
Process proc;
// Cater for cases when the process can't be located.
try
{
proc = Process.GetProcessesByName(procName)[0];
}
catch (IndexOutOfRangeException e)
{
return null;
}
// You need to focus on the application
SetForegroundWindow(proc.MainWindowHandle);
ShowWindow(proc.MainWindowHandle, SW_RESTORE);
// Delay
Thread.Sleep(1000);
Rect rect = new Rect();
IntPtr error = GetWindowRect(proc.MainWindowHandle, ref rect);
// sometimes it gives error.
while (error == (IntPtr)0)
{
error = GetWindowRect(proc.MainWindowHandle, ref rect);
}
int width = rect.right - rect.left;
int height = rect.bottom - rect.top;
Bitmap bmp = new Bitmap(width, height, PixelFormat.Format32bppArgb);
Graphics.FromImage(bmp).CopyFromScreen(rect.left,rect.top,0,0,new Size(width, height),CopyPixelOperation.SourceCopy);
return bmp;
}
public void RecordVideo()
{
// Keep track of time:
watch.Start();
// Save screenshot:
string name = tempPath + "//screenshot-" + fileCount + ".png";
CaptureApplication(handle_name).Save(name, ImageFormat.Png);
inputImageSequence.Add(name);
fileCount++;
// Dispose of bitmap:
CaptureApplication(handle_name).Dispose();
}

Apologies for the brevity and style of this reply; I'm currently on mobile.
Could you express your combobox event handler as:
private void Handlebox_SelectedIndexChanged(object sender, EventArgs e)
{
if (Handlebox.SelectedIndex == -1) return;
handle_name = Handlebox.SelectedItem.ToString();
}
I'm not sure what exactly you want this application to do eventually, but If all you want is to gracefully exit, I would look into registering an event handler that watches for a key combination, and stops and saves the recording when it is pressed. I can't easily type out how to do that, but some concerted googling should help you.

Find out which Windows Explorer window was clicked to start my executable.

I am working on a console executable that may run in multi monitor environment.
It may be started by double clicking on the Exe file name inside Windows Explorer.
I want to move the console to the same monitor as the Windows Explorer window that started it. Is there any way to do it?
I was able to get parent process and get MainWindowHandle.
But it will not give me the correct window. It will give me the first Explorer window. See code below. SetupConsoleWindow is the main function.
internal static class NativeMethods
{
internal const int SWP_NOSIZE = 0x0001;
[DllImport("kernel32.dll")]
internal static extern bool AllocConsole();
[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
internal static extern IntPtr SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int Y, int cx, int cy, int wFlags);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern IntPtr GetConsoleWindow();
}
public static Process GetParentProcess()
{
var currentProcessName = Process.GetProcessById(Process.GetCurrentProcess().Id).ProcessName;
var processesByName = Process.GetProcessesByName(currentProcessName);
for (var index = 0; index < processesByName.Length; index++)
{
string processIndexdName = index == 0 ? currentProcessName : currentProcessName + "#" + index;
var processId = new PerformanceCounter("Process", "ID Process", processIndexdName);
if ((int)processId.NextValue() == Process.GetCurrentProcess().Id)
break;
}
var parentPerformanceCounter = new PerformanceCounter("Process", "Creating Process ID", currentProcessName);
Process parentProcess = Process.GetProcessById((int)parentPerformanceCounter.NextValue());
return parentProcess;
}
public static void SetupConsoleWindow()
{
NativeMethods.AllocConsole();
var parentProcess = GetParentProcess();
if (parentProcess != null)
{
IntPtr consoleWindowHandle = NativeMethods.GetConsoleWindow();
Screen parentScreen = Screen.FromHandle(parentProcess.MainWindowHandle);
Rectangle monitor = parentScreen.WorkingArea;
NativeMethods.SetWindowPos(consoleWindowHandle, 0, monitor.Left, monitor.Top, 0, 0, NativeMethods.SWP_NOSIZE);
}
}

So what you want to do is launch your program on the same monitor as the Windows Explorer window that started it. Doing this the way you currently intend to may be technically possible, but it would be cumbersome and flaky. It would involve enumerating all the open windows, figuring out which ones are Explorer windows, then for each of those which folder is being viewed and then which file is currently selected. You would then compare the name of that file with your program's name and, if multiple such windows are found, choose the most top-level one. You would have to hope that the file did not somehow get deselected between the double click and your main().
This process is well documented here. For reference, here is what the code to get the currently selected item looks like in C++:
#include <shlobj.h>
#include <exdisp.h>
TCHAR g_szPath[MAX_PATH];
TCHAR g_szItem[MAX_PATH];
void CALLBACK RecalcText(HWND hwnd, UINT, UINT_PTR, DWORD)
{
HWND hwndFind = GetForegroundWindow();
g_szPath[0] = TEXT('\0');
g_szItem[0] = TEXT('\0');
IShellWindows *psw;
if (SUCCEEDED(CoCreateInstance(CLSID_ShellWindows, NULL, CLSCTX_ALL,
IID_IShellWindows, (void**)&psw))) {
VARIANT v;
V_VT(&v) = VT_I4;
IDispatch *pdisp;
BOOL fFound = FALSE;
for (V_I4(&v) = 0; !fFound && psw->Item(v, &pdisp) == S_OK;
V_I4(&v)++) {
IWebBrowserApp *pwba;
if (SUCCEEDED(pdisp->QueryInterface(IID_IWebBrowserApp, (void**)&pwba))) {
HWND hwndWBA;
if (SUCCEEDED(pwba->get_HWND((LONG_PTR*)&hwndWBA)) &&
hwndWBA == hwndFind) {
fFound = TRUE;
IServiceProvider *psp;
if (SUCCEEDED(pwba->QueryInterface(IID_IServiceProvider, (void**)&psp))) {
IShellBrowser *psb;
if (SUCCEEDED(psp->QueryService(SID_STopLevelBrowser,
IID_IShellBrowser, (void**)&psb))) {
IShellView *psv;
if (SUCCEEDED(psb->QueryActiveShellView(&psv))) {
IFolderView *pfv;
if (SUCCEEDED(psv->QueryInterface(IID_IFolderView,
(void**)&pfv))) {
IPersistFolder2 *ppf2;
if (SUCCEEDED(pfv->GetFolder(IID_IPersistFolder2,
(void**)&ppf2))) {
LPITEMIDLIST pidlFolder;
if (SUCCEEDED(ppf2->GetCurFolder(&pidlFolder))) {
if (!SHGetPathFromIDList(pidlFolder, g_szPath)) {
lstrcpyn(g_szPath, TEXT("<not a directory>"), MAX_PATH);
}
int iFocus;
if (SUCCEEDED(pfv->GetFocusedItem(&iFocus))) {
LPITEMIDLIST pidlItem;
if (SUCCEEDED(pfv->Item(iFocus, &pidlItem))) {
IShellFolder *psf;
if (SUCCEEDED(ppf2->QueryInterface(IID_IShellFolder,
(void**)&psf))) {
STRRET str;
if (SUCCEEDED(psf->GetDisplayNameOf(pidlItem,
SHGDN_INFOLDER,
&str))) {
StrRetToBuf(&str, pidlItem, g_szItem, MAX_PATH);
}
psf->Release();
}
CoTaskMemFree(pidlItem);
}
}
CoTaskMemFree(pidlFolder);
}
ppf2->Release();
}
pfv->Release();
}
psv->Release();
}
psb->Release();
}
psp->Release();
}
}
pwba->Release();
}
pdisp->Release();
}
psw->Release();
}
InvalidateRect(hwnd, NULL, TRUE);
}
However, you may be making this more complicated than it needs to be. Consider this instead:
Get the current mouse coordinates with Cursor.Position (or GetCursorPos)
Get the monitor on which the mouse cursor is present
Move your window to that monitor

Spy++ doesn't reach button in Qt application

I'm trying to get the properties of a button but when I drag the spy++'s find window tool it doesn't reach the button (of caption "iniciar gravação" in that case) but rather the button grid parent, like this:
Why is that and how can I get the button properties? I tried with auto it info tool but I get the same behavior.
I tried get that button properties from C# code, like this:
public class WindowHandleInfo
{
private delegate bool EnumWindowProc(IntPtr hwnd, IntPtr lParam);
[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr lParam);
private IntPtr _MainHandle;
public WindowHandleInfo(IntPtr handle)
{
this._MainHandle = handle;
}
public List<IntPtr> GetAllChildHandles()
{
List<IntPtr> childHandles = new List<IntPtr>();
GCHandle gcChildhandlesList = GCHandle.Alloc(childHandles);
IntPtr pointerChildHandlesList = GCHandle.ToIntPtr(gcChildhandlesList);
try
{
EnumWindowProc childProc = new EnumWindowProc(EnumWindow);
EnumChildWindows(this._MainHandle, childProc, pointerChildHandlesList);
}
finally
{
gcChildhandlesList.Free();
}
return childHandles;
}
private bool EnumWindow(IntPtr hWnd, IntPtr lParam)
{
GCHandle gcChildhandlesList = GCHandle.FromIntPtr(lParam);
if (gcChildhandlesList == null || gcChildhandlesList.Target == null)
{
return false;
}
List<IntPtr> childHandles = gcChildhandlesList.Target as List<IntPtr>;
childHandles.Add(hWnd);
return true;
}
}
void printWindows(IntPtr parent, int tabLevel)
{
var w = new WindowHandleInfo(parent);
foreach (IntPtr h in w.GetAllChildHandles())
{
string caption = GetTextBoxText(h) ?? "not found";
Debug.Write(new string('\t', tabLevel));
Debug.WriteLine(caption);
printWindows(h, tabLevel + 1);
}
}
int GetTextBoxTextLength(IntPtr hTextBox)
{
// helper for GetTextBoxText
const int WM_GETTEXTLENGTH = 0x000E;
int result = SendMessage(hTextBox, WM_GETTEXTLENGTH, 0, IntPtr.Zero);
return result;
}
string GetTextBoxText(IntPtr hTextBox)
{
const int WM_GETTEXT = 0x000D;
int len = GetTextBoxTextLength(hTextBox);
if (len <= 0) return null; // no text
StringBuilder sb = new StringBuilder(len + 1);
SendMessage(hTextBox, WM_GETTEXT, len + 1, sb);
return sb.ToString();
}
using like this:
IntPtr parent = FindWindow(IntPtr.Zero, "my app title");
printWindows(parent, 0);
But I can't see anyhing related to Iniciar gravação button.

Qt UI controls (widgets, in Qt lexicon. Aka buttons, line edits, comboboxes, etc.) are not backed by native controls. They just steal the native UI look and feel from them and mimic it.
For this reason, you won't find those controls using some of those "spy" tools -- you may still find them through accessibility, though (*).
Or, you can inspect your application using other Qt-specific tools, such as GammaRay for debugging or Squish for UI testing.
(*) controls shipped with Qt are accessibile, but if someone manually reimplements something that looks like a button and doesn't provide it with accessibility then you can't do much about that.

How to Disable Autoscrolling in richtextbox in c#

i want to disable the scrolling feature of richtextbox in c#. i just want to make richtextbox to allow user to enter only in its size area, means no vertical scrolling for user. just like MS-word or open Office Pages.thanx in advance.

You should override WndProc and block WM_SETFOCUS.
protected override void WndProc(ref Message m)
{
if(m.Msg != WM_SETFOCUS)
base.WndProc(ref m);
}
Here is a tutorial about this : How to: C# - Prevent RichTextBox from auto scrolling

This worked for me.
First thing as you may have seen in other posts you need access to user32.dll from C#.
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam);
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern int SendMessage(IntPtr hwndLock,Int32 wMsg,Int32 wParam, ref Point pt);
We need to make some constant declaration to make the SendMessage calls properly.
private const int WM_USER = 0x400;
private const int EM_HIDESELECTION = WM_USER + 63;
private const int WM_SETREDRAW = 0x000B;
private const int EM_GETSCROLLPOS = WM_USER + 221;
private const int EM_SETSCROLLPOS = WM_USER + 222;
Then, some public static methods to be used whenever we need to stop scrolling.
public static void Suspend(Control control)
{
Message msgSuspendUpdate = Message.Create(control.Handle, WM_SETREDRAW, IntPtr.Zero,
IntPtr.Zero);
NativeWindow window = NativeWindow.FromHandle(control.Handle);
window.DefWndProc(ref msgSuspendUpdate);
}
public static void Resume(Control control)
{
// Create a C "true" boolean as an IntPtr
IntPtr wparam = new IntPtr(1);
Message msgResumeUpdate = Message.Create(control.Handle, WM_SETREDRAW, wparam,
IntPtr.Zero);
NativeWindow window = NativeWindow.FromHandle(control.Handle);
window.DefWndProc(ref msgResumeUpdate);
control.Invalidate();
}
public static Point GetScrollPoint(Control control) {
Point point = new Point();
SendMessage(control.Handle, EM_GETSCROLLPOS, 0, ref point);
return point;
}
public static void SetScrollPoint(Control control, Point point)
{
SendMessage(control.Handle, EM_SETSCROLLPOS, 0, ref point);
}
The Suspend method stops the Control to make a redraw on the screen. The Resume method restarts redraws on the screen for the given Control.
The GetScrollPoint method gets the actual Point where the scroll caret is located. The SetScrollPoint puts the scroll caret at the given point.
How to use these methods? First, given a Control you need to stop autoscroll, make the call to Suspend, then to GetScrollPoint, (make what you need to do with the control, like highlight or append text) then SetScrollPoint and finally Resume.
In my case, I wanted to copy the entire line of a RichTextBox at any time when the cursor moves from line to line. (Doing so produce a scroll on long lines).
This is my working method:
private int intLastLine = -1;
private void richTextBoxSwitch_SelectionChanged(object sender, EventArgs e)
{
try
{
if (this.richTextBoxSwitch.TextLength > 0)
{
ControlBehavior.Suspend(this.richTextBoxSwitch);
Point point = ControlBehavior.GetScrollPoint(this.richTextBoxSwitch);
int intSelectionStartBackup = this.richTextBoxSwitch.SelectionStart;
int intSelectionLengthBackup = this.richTextBoxSwitch.SelectionLength;
int intCharIndex = this.richTextBoxSwitch.GetFirstCharIndexOfCurrentLine();
int intLine = this.richTextBoxSwitch.GetLineFromCharIndex(intCharIndex);
this.richTextBoxSwitch.SuspendLayout();
if (intLastLine != intLine)
{
intLastLine = intLine;
int intLength = this.richTextBoxSwitch.Lines[intLine].Length;
this.richTextBoxSwitch.Select(intCharIndex, intLength);
this.richTextBoxSwitch.BackColor = ColorMessageBackground;
strData = this.richTextBoxSwitch.SelectedText;
this.textBoxMessageSelected.Text = strData.Trim();
this.richTextBoxSwitch.Select(intSelectionStartBackup, intSelectionLengthBackup);
}
this.richTextBoxSwitch.ResumeLayout();
ControlBehavior.SetScrollPoint(this.richTextBoxSwitch, point);
ControlBehavior.Resume(this.richTextBoxSwitch);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
Hope this helps!

Programmatically Determine a Duration of a Locked Workstation?

How can one determine, in code, how long the machine is locked?
Other ideas outside of C# are also welcome.
I like the windows service idea (and have accepted it) for simplicity and cleanliness, but unfortunately I don't think it will work for me in this particular case. I wanted to run this on my workstation at work rather than home (or in addition to home, I suppose), but it's locked down pretty hard courtesy of the DoD. That's part of the reason I'm rolling my own, actually.
I'll write it up anyway and see if it works. Thanks everyone!

I hadn't found this before, but from any application you can hookup a SessionSwitchEventHandler. Obviously your application will need to be running, but so long as it is:
Microsoft.Win32.SystemEvents.SessionSwitch += new Microsoft.Win32.SessionSwitchEventHandler(SystemEvents_SessionSwitch);
void SystemEvents_SessionSwitch(object sender, Microsoft.Win32.SessionSwitchEventArgs e)
{
if (e.Reason == SessionSwitchReason.SessionLock)
{
//I left my desk
}
else if (e.Reason == SessionSwitchReason.SessionUnlock)
{
//I returned to my desk
}
}

I would create a Windows Service (a visual studio 2005 project type) that handles the OnSessionChange event as shown below:
protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
if (changeDescription.Reason == SessionChangeReason.SessionLock)
{
//I left my desk
}
else if (changeDescription.Reason == SessionChangeReason.SessionUnlock)
{
//I returned to my desk
}
}
What and how you log the activity at that point is up to you, but a Windows Service provides quick and easy access to windows events like startup, shutdown, login/out, along with the lock and unlock events.

The solution below uses the Win32 API. OnSessionLock is called when the workstation is locked, and OnSessionUnlock is called when it is unlocked.
[DllImport("wtsapi32.dll")]
private static extern bool WTSRegisterSessionNotification(IntPtr hWnd,
int dwFlags);
[DllImport("wtsapi32.dll")]
private static extern bool WTSUnRegisterSessionNotification(IntPtr
hWnd);
private const int NotifyForThisSession = 0; // This session only
private const int SessionChangeMessage = 0x02B1;
private const int SessionLockParam = 0x7;
private const int SessionUnlockParam = 0x8;
protected override void WndProc(ref Message m)
{
// check for session change notifications
if (m.Msg == SessionChangeMessage)
{
if (m.WParam.ToInt32() == SessionLockParam)
OnSessionLock(); // Do something when locked
else if (m.WParam.ToInt32() == SessionUnlockParam)
OnSessionUnlock(); // Do something when unlocked
}
base.WndProc(ref m);
return;
}
void OnSessionLock()
{
Debug.WriteLine("Locked...");
}
void OnSessionUnlock()
{
Debug.WriteLine("Unlocked...");
}
private void Form1Load(object sender, EventArgs e)
{
WTSRegisterSessionNotification(this.Handle, NotifyForThisSession);
}
// and then when we are done, we should unregister for the notification
// WTSUnRegisterSessionNotification(this.Handle);

I know this is an old question but i have found a method to get the Lock State for a given session.
I found my answer here but it was in C++ so i translated as much as i can to C# to get the Lock State.
So here goes:
static class SessionInfo {
private const Int32 FALSE = 0;
private static readonly IntPtr WTS_CURRENT_SERVER = IntPtr.Zero;
private const Int32 WTS_SESSIONSTATE_LOCK = 0;
private const Int32 WTS_SESSIONSTATE_UNLOCK = 1;
private static bool _is_win7 = false;
static SessionInfo() {
var os_version = Environment.OSVersion;
_is_win7 = (os_version.Platform == PlatformID.Win32NT && os_version.Version.Major == 6 && os_version.Version.Minor == 1);
}
[DllImport("wtsapi32.dll")]
private static extern Int32 WTSQuerySessionInformation(
IntPtr hServer,
[MarshalAs(UnmanagedType.U4)] UInt32 SessionId,
[MarshalAs(UnmanagedType.U4)] WTS_INFO_CLASS WTSInfoClass,
out IntPtr ppBuffer,
[MarshalAs(UnmanagedType.U4)] out UInt32 pBytesReturned
);
[DllImport("wtsapi32.dll")]
private static extern void WTSFreeMemoryEx(
WTS_TYPE_CLASS WTSTypeClass,
IntPtr pMemory,
UInt32 NumberOfEntries
);
private enum WTS_INFO_CLASS {
WTSInitialProgram = 0,
WTSApplicationName = 1,
WTSWorkingDirectory = 2,
WTSOEMId = 3,
WTSSessionId = 4,
WTSUserName = 5,
WTSWinStationName = 6,
WTSDomainName = 7,
WTSConnectState = 8,
WTSClientBuildNumber = 9,
WTSClientName = 10,
WTSClientDirectory = 11,
WTSClientProductId = 12,
WTSClientHardwareId = 13,
WTSClientAddress = 14,
WTSClientDisplay = 15,
WTSClientProtocolType = 16,
WTSIdleTime = 17,
WTSLogonTime = 18,
WTSIncomingBytes = 19,
WTSOutgoingBytes = 20,
WTSIncomingFrames = 21,
WTSOutgoingFrames = 22,
WTSClientInfo = 23,
WTSSessionInfo = 24,
WTSSessionInfoEx = 25,
WTSConfigInfo = 26,
WTSValidationInfo = 27,
WTSSessionAddressV4 = 28,
WTSIsRemoteSession = 29
}
private enum WTS_TYPE_CLASS {
WTSTypeProcessInfoLevel0,
WTSTypeProcessInfoLevel1,
WTSTypeSessionInfoLevel1
}
public enum WTS_CONNECTSTATE_CLASS {
WTSActive,
WTSConnected,
WTSConnectQuery,
WTSShadow,
WTSDisconnected,
WTSIdle,
WTSListen,
WTSReset,
WTSDown,
WTSInit
}
public enum LockState {
Unknown,
Locked,
Unlocked
}
[StructLayout(LayoutKind.Sequential)]
private struct WTSINFOEX {
public UInt32 Level;
public UInt32 Reserved; /* I have observed the Data field is pushed down by 4 bytes so i have added this field as padding. */
public WTSINFOEX_LEVEL Data;
}
[StructLayout(LayoutKind.Sequential)]
private struct WTSINFOEX_LEVEL {
public WTSINFOEX_LEVEL1 WTSInfoExLevel1;
}
[StructLayout(LayoutKind.Sequential)]
private struct WTSINFOEX_LEVEL1 {
public UInt32 SessionId;
public WTS_CONNECTSTATE_CLASS SessionState;
public Int32 SessionFlags;
/* I can't figure out what the rest of the struct should look like but as i don't need anything past the SessionFlags i'm not going to. */
}
public static LockState GetSessionLockState(UInt32 session_id) {
IntPtr ppBuffer;
UInt32 pBytesReturned;
Int32 result = WTSQuerySessionInformation(
WTS_CURRENT_SERVER,
session_id,
WTS_INFO_CLASS.WTSSessionInfoEx,
out ppBuffer,
out pBytesReturned
);
if (result == FALSE)
return LockState.Unknown;
var session_info_ex = Marshal.PtrToStructure<WTSINFOEX>(ppBuffer);
if (session_info_ex.Level != 1)
return LockState.Unknown;
var lock_state = session_info_ex.Data.WTSInfoExLevel1.SessionFlags;
WTSFreeMemoryEx(WTS_TYPE_CLASS.WTSTypeSessionInfoLevel1, ppBuffer, pBytesReturned);
if (_is_win7) {
/* Ref: https://msdn.microsoft.com/en-us/library/windows/desktop/ee621019(v=vs.85).aspx
* Windows Server 2008 R2 and Windows 7: Due to a code defect, the usage of the WTS_SESSIONSTATE_LOCK
* and WTS_SESSIONSTATE_UNLOCK flags is reversed. That is, WTS_SESSIONSTATE_LOCK indicates that the
* session is unlocked, and WTS_SESSIONSTATE_UNLOCK indicates the session is locked.
* */
switch (lock_state) {
case WTS_SESSIONSTATE_LOCK:
return LockState.Unlocked;
case WTS_SESSIONSTATE_UNLOCK:
return LockState.Locked;
default:
return LockState.Unknown;
}
}
else {
switch (lock_state) {
case WTS_SESSIONSTATE_LOCK:
return LockState.Locked;
case WTS_SESSIONSTATE_UNLOCK:
return LockState.Unlocked;
default:
return LockState.Unknown;
}
}
}
}
Note: The above code was extracted from a much larger project so if i missed a bit sorry. I havn't got time to test the above code but plan to come back in a week or two to check everything. I only posted it now because i didn't want to forget to do it.

NOTE: This is not an answer, but a (contribution) to Timothy Carter answer, because my reputation doesn't allow me to comment so far.
Just in case somebody tried the code from Timothy Carter's answer and did not get it to work right away in a Windows service, there's one property that need to be set to true in the constructor of the service.
Just add the line in the constructor:
CanHandleSessionChangeEvent = true;
And be sure not to set this property after the service is started otherwise an InvalidOperationException will be thrown.

If you're interested in writing a windows-service to "find" these events, topshelf (the library/framework that makes writing windows services much easier) has a hook.
public interface IMyServiceContract
{
void Start();
void Stop();
void SessionChanged(Topshelf.SessionChangedArguments args);
}
public class MyService : IMyServiceContract
{
public void Start()
{
}
public void Stop()
{
}
public void SessionChanged(SessionChangedArguments e)
{
Console.WriteLine(e.ReasonCode);
}
}
and now the code to wire up the topshelf service to the interface/concrete above
Everything below is "typical" topshelf setup.... except for 2 lines which I marked as
/* THIS IS MAGIC LINE */
Those are what get the SessionChanged method to fire.
I tested this with windows 10 x64. I locked and unlocked my machine and I got the desired result.
IMyServiceContract myServiceObject = new MyService(); /* container.Resolve<IMyServiceContract>(); */
HostFactory.Run(x =>
{
x.Service<IMyServiceContract>(s =>
{
s.ConstructUsing(name => myServiceObject);
s.WhenStarted(sw => sw.Start());
s.WhenStopped(sw => sw.Stop());
s.WhenSessionChanged((csm, hc, chg) => csm.SessionChanged(chg)); /* THIS IS MAGIC LINE */
});
x.EnableSessionChanged(); /* THIS IS MAGIC LINE */
/* use command line variables for the below commented out properties */
/*
x.RunAsLocalService();
x.SetDescription("My Description");
x.SetDisplayName("My Display Name");
x.SetServiceName("My Service Name");
x.SetInstanceName("My Instance");
*/
x.StartManually(); // Start the service manually. This allows the identity to be tweaked before the service actually starts
/* the below map to the "Recover" tab on the properties of the Windows Service in Control Panel */
x.EnableServiceRecovery(r =>
{
r.OnCrashOnly();
r.RestartService(1); ////first
r.RestartService(1); ////second
r.RestartService(1); ////subsequents
r.SetResetPeriod(0);
});
x.DependsOnEventLog(); // Windows Event Log
x.UseLog4Net();
x.EnableShutdown();
x.OnException(ex =>
{
/* Log the exception */
/* not seen, I have a log4net logger here */
});
});
My packages.config to provide hints about versions:
<package id="log4net" version="2.0.5" targetFramework="net45" />
<package id="Topshelf" version="4.0.3" targetFramework="net461" />
<package id="Topshelf.Log4Net" version="4.0.3" targetFramework="net461" />

In Windows Task Scheduler, you could create tasks that trigger on workstation lock and on workstation unlock. Each task could write a flag and timestamp to a file to state if the workstation is locked or unlocked and when it happened.
I realize that this is not a programmatic way. It is simpler than writing a service. It won't miss an event because your program happens to not be running at the time of lock/unlock transition.

Below is the 100% working code to find if the PC is locked or not.
Before using this use the namespace System.Runtime.InteropServices.
[DllImport("user32", EntryPoint = "OpenDesktopA", CharSet = CharSet.Ansi,SetLastError = true, ExactSpelling = true)]
private static extern Int32 OpenDesktop(string lpszDesktop, Int32 dwFlags, bool fInherit, Int32 dwDesiredAccess);
[DllImport("user32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
private static extern Int32 CloseDesktop(Int32 hDesktop);
[DllImport("user32", CharSet = CharSet.Ansi,SetLastError = true,ExactSpelling = true)]
private static extern Int32 SwitchDesktop(Int32 hDesktop);
public static bool IsWorkstationLocked()
{
const int DESKTOP_SWITCHDESKTOP = 256;
int hwnd = -1;
int rtn = -1;
hwnd = OpenDesktop("Default", 0, false, DESKTOP_SWITCHDESKTOP);
if (hwnd != 0)
{
rtn = SwitchDesktop(hwnd);
if (rtn == 0)
{
// Locked
CloseDesktop(hwnd);
return true;
}
else
{
// Not locked
CloseDesktop(hwnd);
}
}
else
{
// Error: "Could not access the desktop..."
}
return false;
}