- 1 year ago
Take screenshot right before Windows locks
To capture a screenshot right before Windows locks, you can use a combination of the Windows API and a timer. Here's an example in C#:
csharpusing System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Threading;
using System.Windows.Forms;
class Program
{
private static Timer timer;
private static IntPtr desktop;
private static Bitmap screenshot;
[DllImport("user32.dll")]
private static extern IntPtr GetDC(IntPtr hwnd);
[DllImport("user32.dll")]
private static extern bool ReleaseDC(IntPtr hwnd, IntPtr dc);
static void Main()
{
// Subscribe to the SessionEnding event
SystemEvents.SessionEnding += SystemEvents_SessionEnding;
// Capture the screen when the timer elapses
timer = new Timer(CaptureScreen, null, Timeout.Infinite, Timeout.Infinite);
timer.Change(TimeSpan.Zero, TimeSpan.FromSeconds(1));
// Start the application message loop
Application.Run();
}
private static void SystemEvents_SessionEnding(object sender, SessionEndingEventArgs e)
{
// Stop the timer and capture the final screenshot
timer.Change(Timeout.Infinite, Timeout.Infinite);
CaptureScreen(null);
}
private static void CaptureScreen(object state)
{
// Release any previous screenshot
screenshot?.Dispose();
// Get the screen size
var screenBounds = Screen.PrimaryScreen.Bounds;
int width = screenBounds.Width;
int height = screenBounds.Height;
// Create a new bitmap for the screenshot
screenshot = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
// Capture the screen
using (Graphics graphics = Graphics.FromImage(screenshot))
{
IntPtr dc = IntPtr.Zero;
try
{
dc = GetDC(IntPtr.Zero);
if (dc != IntPtr.Zero)
{
using (var screenGraphics = Graphics.FromHdc(dc))
{
graphics.CopyFromScreen(0, 0, 0, 0, new Size(width, height));
}
}
}
finally
{
if (dc != IntPtr.Zero)
ReleaseDC(IntPtr.Zero, dc);
}
}
// Save the screenshot to a file or perform any other desired operation
screenshot.Save("screenshot.png");
}
}
In the above example, we utilize the SystemEvents.SessionEnding
event to capture the screenshot when the session is ending (such as when Windows is locking). The CaptureScreen
method captures the screen using the Graphics.CopyFromScreen
method and saves it to a file (screenshot.png
in this example).
Make sure to handle any necessary file permissions and adjust the save location and file format as needed.
Compile and run the application, and it will continuously capture screenshots until the session ends. When the session ends (e.g., Windows locks), the SystemEvents.SessionEnding
event is triggered, and the final screenshot is captured and saved.
Note: This example uses the Windows Forms System.Windows.Forms.Application.Run
method to start the application message loop.