Programmatically Taking a Screen Snapshot

An Overview

Honestly, this lesson is not primarily focusing on how to take a screen snapshot! Instead, it is focusing on how to simulate keyboard strokes and send them to the active application.

In .NET, this is done using the System.Windows.Forms.Forms.SendKeys class. As you might guess it is located in System.Windows.Forms.dll.

Using the SendKeys class you can call static methods like SendWait() to send the keystrokes and wait for them to be processed, or you can send them via the Send() method if you do not care about whether they processed or not.

Calling Send() and SendKeys() functions

Both Send() and SendKeys() requires a single argument keys. This argument represents the keys to send it. Each key is represented by one or more characters. To get list of all values supported for this argument visit the documentation for the SendKeys class, visit this page.

Code Sample

For our example we will try to combine two keys Alt + Print Screen. Alt represented by a percent (%) sign. Print Screen key is represented by the value PrtSc enclosed in curly brackets.

public static Image TakeScreenSnapshot(bool activeWindowOnly)
{
    // PrtSc = Print Screen Key

    string keys = "{PrtSc}";

    if (activeWindowOnly)
        keys = "%" + keys; // % = Alt

    SendKeys.SendWait(keys);

    return Clipboard.GetImage();
}

Enjoy.