How to Write a Screen Recorder in .NET?

Question

Is there a way to make a screen recorder in C#? If so, does anybody know of any tutorials I could use or any information on the subject?

Answer 1

Take a look at this VB.NET code.

Public Class ScreenRecorder

Private Shared tempDir As String = My.Computer.FileSystem.SpecialDirectories.Temp & "snapshot"
Private Shared snap As New System.Threading.Thread(AddressOf Snapshot)
Private Shared _Bounds As System.Drawing.Rectangle = System.Windows.Forms.Screen.PrimaryScreen.Bounds

Public Shared Property Bounds() As System.Drawing.Rectangle
    Get
        Return _Bounds
    End Get
    Set(ByVal value As System.Drawing.Rectangle)
        _Bounds = value
    End Set
End Property

Private Shared Sub Snapshot()
    If Not My.Computer.FileSystem.DirectoryExists(tempDir) Then _
        My.Computer.FileSystem.CreateDirectory(tempDir)
    Dim Co As Integer = 0
    Do
        Co += 1
        System.Threading.Thread.Sleep(50)
        Dim X As New System.Drawing.Bitmap(_Bounds.Width, _Bounds.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb)
        Using G = System.Drawing.Graphics.FromImage(X)
            G.CopyFromScreen(_Bounds.Location, New System.Drawing.Point(), _Bounds.Size)
            Dim CurBounds As New System.Drawing.Rectangle(System.Windows.Forms.Cursor.Position - Bounds.Location, System.Windows.Forms.Cursor.Current.Size)
            Forms.Cursors.Default.Draw(G, CurBounds)
        End Using
        Dim FS As New IO.FileStream(tempDir & FormatString(Co.ToString, 5, "0"c) & ".png", IO.FileMode.OpenOrCreate)
        X.Save(FS, System.Drawing.Imaging.ImageFormat.Png)
        X.Dispose()
        FS.Close()
    Loop
End Sub

Public Shared Sub ClearRecording()
    If My.Computer.FileSystem.DirectoryExists(tempDir) Then _
    My.Computer.FileSystem.DeleteDirectory(tempDir, FileIO.DeleteDirectoryOption.DeleteAllContents)
    My.Computer.FileSystem.CreateDirectory(tempDir)
End Sub

Public Shared Sub Save(ByVal Output As String)
    Dim G As New Windows.Media.Imaging.GifBitmapEncoder

    Dim X As New List(Of IO.FileStream)
    For Each Fi As String In My.Computer.FileSystem.GetFiles(tempDir, FileIO.SearchOption.SearchTopLevelOnly, "*.png")
        Dim TempStream As New IO.FileStream(Fi, IO.FileMode.Open)
        Dim Frame = Imaging.BitmapFrame.Create(TempStream)
        X.Add(TempStream)
        G.Frames.Add(Frame)
    Next
    Dim FS As New IO.FileStream(Output, IO.FileMode.OpenOrCreate)
    G.Save(FS)
    FS.Close()

    For Each St As IO.FileStream In X
        St.Close()

    Next

End Sub

Public Shared Sub Start()
    snap = New System.Threading.Thread(AddressOf Snapshot)
    snap.Start()
End Sub

Public Shared Sub [Stop]()
    snap.Abort()
End Sub

Private Shared Function FormatString(ByVal S As String, ByVal places As Integer, ByVal character As Char) As String
    If S.Length >= places Then Return S
    For X As Integer = S.Length To places
        S = character & S
    Next
    Return S
End Function

End Class

Answer 2

I took the VB.net code from Lucas McCoy and turned it into C#. This records for 5 seconds and saved the gif to desktop. PS: I get an error sometimes when the last screenshot is still aborting via the thread and then the stream tries to read it.

Very slow code.

using System;
using System.Collections.Generic;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;


namespace ConsoleApplication1
{

    public class ScreenRecorder
    {

        private static string tempDir = Path.GetTempPath() + "/snapshot/";
        private static System.Threading.Thread snap = new System.Threading.Thread(Snapshot);

        private static System.Drawing.Rectangle _Bounds = System.Windows.Forms.Screen.PrimaryScreen.Bounds;
        public static System.Drawing.Rectangle Bounds
        {
            get { return _Bounds; }
            set { _Bounds = value; }
        }

        private static void Snapshot()
        {
            if (!Directory.Exists(tempDir))
                Directory.CreateDirectory(tempDir);
            int Co = 0;
            do
            {
                Co += 1;
                System.Threading.Thread.Sleep(50);
                System.Drawing.Bitmap X = new System.Drawing.Bitmap(_Bounds.Width, _Bounds.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
                using(System.Drawing.Graphics G = System.Drawing.Graphics.FromImage(X)) {
                    G.CopyFromScreen(_Bounds.Location, new System.Drawing.Point(), _Bounds.Size);
                    System.Drawing.Rectangle CurBounds = new System.Drawing.Rectangle(System.Drawing.Point.Subtract(System.Windows.Forms.Cursor.Position,Bounds.Size), System.Windows.Forms.Cursor.Current.Size);
                    System.Windows.Forms.Cursors.Default.Draw(G, CurBounds);
               }
                System.IO.FileStream FS = new System.IO.FileStream(tempDir + FormatString(Co.ToString(), 5, '0') + ".png", System.IO.FileMode.OpenOrCreate);
                X.Save(FS, System.Drawing.Imaging.ImageFormat.Png);
                X.Dispose();
                FS.Close();
            } while (true);
        }

        public static void ClearRecording()
        {
            if (Directory.Exists(tempDir))
                Directory.Delete(tempDir, true);
                Directory.CreateDirectory(tempDir);
        }

        public static void Save(string Output)
        {
            System.Windows.Media.Imaging.GifBitmapEncoder G = new System.Windows.Media.Imaging.GifBitmapEncoder();

            List<System.IO.FileStream> X = new List<System.IO.FileStream>();
            foreach (string Fi in Directory.GetFiles(tempDir, "*.png", SearchOption.TopDirectoryOnly))
            {
                System.IO.FileStream TempStream = new System.IO.FileStream(Fi, System.IO.FileMode.Open);
                System.Windows.Media.Imaging.BitmapFrame Frame = System.Windows.Media.Imaging.BitmapFrame.Create(TempStream);
                X.Add(TempStream);
                G.Frames.Add(Frame);
            }
            System.IO.FileStream FS = new System.IO.FileStream(Output, System.IO.FileMode.OpenOrCreate);
            G.Save(FS);
            FS.Close();

            foreach (System.IO.FileStream St in X)
            {
                St.Close();

            }

        }

        public static void Start()
        {
            snap = new System.Threading.Thread(Snapshot);
            snap.Start();
        }

        public static void Stop()
        {
            snap.Abort();
        }

        private static string FormatString(string S, int places, char character)
        {
            if (S.Length >= places)
                return S;
            for (int X = S.Length; X <= places; X++)
            {
                S = character + S;
            }
            return S;
        }

    }

    class Program
    {
        static void Main(string[] args)
        {
            ScreenRecorder.Start();
            System.Threading.Thread.Sleep(5000);
            ScreenRecorder.Stop();
            ScreenRecorder.Save(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "\\video.gif");
            ScreenRecorder.ClearRecording();
        }
    }
}

These are references I had to add:

Answer 3

For the Thread Exception, you can avoid that with this code

    public static void Stop()
    {
        flag = false;
        snap.Join();
    }

and put the flag as static private bool (global) and put it instead of the true value in the while loop:

while(flag)

that how you can avoid threading overlap on resource. I know that is not the subject but I want to share this piece of info because threads always make the debugging nasty.

Regards, Fawaz