Windows keyboard event

So you can think of the event viewer as a database that records every activity on your computer. If you explore the event viewer in-depth, you will see different information, warnings, and plenty of errors. Even the best-maintained computers show plenty of errors and warnings. There are 3 main ways you can gain access to the event viewer on Windows 10 — via the Start menu, Run dialogue, and the command line. You will be greeted with this page:. When you open the event viewer to see your computer's activity logs, you are automatically shown the Event Viewer Local tab.

But this might not contain the details you need, as it's just a page you are greeted with when you open the Event Viewer. Application Events: Information, errors, and warning reports of program activities.

Security Events: This shows the results of various security actions. They are called audits and each of them can be a success or a failure. Setup Event: this has to do with domain controllers, which is a server that verifies users on computer networks.

System Events: these are reports from system files detailing the errors they have encountered. Forwarded Events: these are sent to your computer from other computers in the same network. The nCode parameter is a hook code that the hook procedure uses to determine the action to perform. The value of the hook code depends on the type of the hook; each type has its own characteristic set of hook codes.

The values of the wParam and lParam parameters depend on the hook code, but they typically contain information about a message that was sent or posted.

The SetWindowsHookEx function always installs a hook procedure at the beginning of a hook chain. When an event occurs that is monitored by a particular type of hook, the system calls the procedure at the beginning of the hook chain associated with the hook.

Each hook procedure in the chain determines whether to pass the event to the next procedure. A hook procedure passes an event to the next procedure by calling the CallNextHookEx function.

Note that the hook procedures for some types of hooks can only monitor messages. A global hook monitors messages for all threads in the same desktop as the calling thread.

A thread-specific hook monitors messages for only an individual thread. A global hook procedure can be called in the context of any application in the same desktop as the calling thread, so the procedure must be in a separate DLL module. A thread-specific hook procedure is called only in the context of the associated thread.

If an application installs a hook procedure for one of its own threads, the hook procedure can be in either the same module as the rest of the application's code or in a DLL. If the application installs a hook procedure for a thread of a different application, the procedure must be in a DLL. For information, see Dynamic-Link Libraries. You should use global hooks only for debugging purposes; otherwise, you should avoid them. Global hooks hurt system performance and cause conflicts with other applications that implement the same type of global hook.

Each type of hook enables an application to monitor a different aspect of the system's message-handling mechanism. The following sections describe the available hooks. The structure contains the return value from the window procedure that processed the message, as well as the message parameters associated with the message.

Subclassing the window does not work for messages set between processes. The value the hook procedure returns determines whether the system allows or prevents one of these operations. In some respects this mapping is unfortunate, because you should never think of virtual-key codes as characters, for the reasons discussed. The header file WinUser.

For the complete list of virtual-key codes, see Virtual-Key Codes. Instead, just use the numeric value. There are two types of system key:. The F10 key activates the menu bar of a window. Various ALT-key combinations invoke system commands. In addition, if a window has a menu, the ALT key can be used to activate menu items. Some ALT key combinations do not do anything. This includes the function keys other than F If you hold down a key long enough to start the keyboard's repeat feature, the system sends multiple key-down messages, followed by a single key-up message.

In all four of the keyboard messages discussed so far, the wParam parameter contains the virtual-key code of the key. The lParam parameter contains some miscellaneous information packed into 32 bits.

You typically do not need the information in lParam. One flag that might be useful is bit 30, the "previous key state" flag, which is set to 1 for repeated key-down messages.

As the name implies, system key strokes are primarily intended for use by the operating system. Otherwise, you will block the operating system from handling the command. Key strokes are converted into characters by the TranslateMessage function, which we first saw in Module 1.

This function examines key-down messages and translates them into characters. The wParam parameter of the message contains the UTF character. Assuming a standard keyboard layout, you would get the following sequence of messages:.