Mouse & Keyboard Recorder for .NET
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This application is
designed to record user mouse activity, and keyboard presses from anywhere on
the desktop, even when other applications have the focus.
This type of application
can be used in many different scenarios, such as –
- A remote pointer application
- A go-anywhere colour picker feature
- Macro generation software
- Key logging utilities
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One key feature of this
application is that it uses events to model user actions. This means that the
calling application need not constantly poll sets of properties for changes. As
you will see in the code, the program is divided into two loosely coupled
files, namely Form1.cs (the user interface) and another called InputListener.cs
(the nuts & bolts of the software).
Although .NET allows you to
track mouse activity using the Control.MouseButtons and Control.MousePosition classes, there is no native means of capturing global
key-presses. To achieve this functionality, a Win32 API function is used,
namely GetAsyncKeyState. This function
takes a numeric keyboard scan-code as a parameter and returns –32767 (referred
to as int16.MinValue+1 in code) if the key is pressed.
Keyboard scan-codes for
standard alphanumeric keys are quite straightforward. Keys A-Z are mapped to
their uppercase ASCII equivalent. Keys 0-9 (excluding the numeric keypad) are
directly mapped to their ASCII equivalent. Extended keys such as delete or
enter are mapped to unprintable ASCII codes, and appear as strange symbols in
the display, as can be seen from the screenshot above. A bit of experimentation
with the application will help you discover the codes for the rest of the
keyboard.
Without further delay, lets
start coding the application. Start off by creating a new C# Windows Forms project
named “Recorder” in Visual Studio .NET. Right click on Solution Explorer and
add a new class named InputListener.
Enter the following code as
the body of the InputListener class. It is used simply to set up a new thread
that runs an infinite loop, which will act as the underlying polling mechanism.
This underlying polling mechanism will be completely transparent to the calling
application.
public class InputListener
{
public void Run()
{
Thread thdMain = new
Thread(new ThreadStart(RunThread));
thdMain.Start();
}
private void RunThread()
{
while(true)
{
Thread.Sleep(10);
}
}
}
It is a unwritten coding
convention that all events should contain two parameters, an object referring
to the source of the event, and a second object, derived from EventArgs and
containing any further information the ‘subscribing’ application may need. The
first event we will deal with is the Mouse Move Event, this uses the
MouseMoveEventArgs class, which is defined thus (and included in the body of
the Recorder Namespace in InputListener.cs):
public class MouseMoveEventArgs : EventArgs
{
public
MouseMoveEventArgs(int X,int Y)
{
this.X
= X;
this.Y
= Y;
}
public readonly int X;
public readonly int Y;
}
In the input listener class,
we must define the Event, and the delegate for this event, using the following
code
private int lastX = 0;
private int lastY = 0;
public delegate void
MouseMoveHandler
(object inputListener,
MouseMoveEventArgs
mouseMoveInfo);
public event MouseMoveHandler OnMouseMove;
This event is generated by
monitoring the Control.MousePosition class for changes. The best place to do this is within the loop in the
RunThread method, that we created earlier. Therefore, add the following code
directly after the Thread.Sleep(10); in RunThread().
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