Windows USER is a component of the
Microsoft Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
operating system that provides core functionality for building simple
user interfaces. The component has existed in all versions of Windows, and includes functionality for
window management
A window manager is system software that controls the placement and appearance of windows within a windowing system in a graphical user interface. Most window managers are designed to help provide a desktop environment. They work in conjunction ...
,
message passing,
input processing and standard
controls.
Functionality and role
Windows USER provides a large part of the core user experience for Microsoft Windows. Historically, it was responsible for:
[Petzold, Charles (1998). ''Programming Windows Fifth Edition'', Microsoft Press, .]
[Chen, Raymond (2007). ''The Old New Thing'', Addison-Wesley Professional,
]
* Causing windows to be drawn (using
GDI as a device-independent API for drawing primitives)
* Obscuring
overlapping windows behind others
* Window size and positioning
* Providing all the standard window management controls (such as close boxes or
title bar
A title is one or more words used before or after a person's name, in certain contexts. It may signify either generation, an official position, or a professional or academic qualification. In some languages, titles may be inserted between the f ...
s)
* Providing the standard Windows
menu bar
A menu bar is a graphical control element which contains drop-down menus.
The menu bar's purpose is to supply a common housing for window- or application-specific menus which provide access to such functions as opening files, interacting wi ...
* Providing of standard controls (such as
button,
List box or
Edit Box)
* Providing
dialog box management (short-cut keys, tab key processing)
* Processing all user input from the mouse and keyboard
* The
desktop background image
* Drawing all standard visual elements
*
Inter-process communication
In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categori ...
using
Dynamic Data Exchange
* Mouse pointer cursor display and management
* Data transfer (
Clipboard)
Gradually, as Windows has become larger and better factored, Windows USER has cooperated with other components to provide this functionality:
* Controls: Starting with
Windows 95, new controls were placed into a separate common controls component. Starting with
Windows XP, new implementations of the standard controls were also moved to that same component.
* Windows Management experience: Starting with
Windows Vista, drawing standard window management was moved from Windows USER to the
Desktop Window Manager.
* Standard Visuals: Starting with Windows XP, visual elements are drawn by the Theming component.
* Inter-program communication: Starting with Windows 3.1,
Object Linking and Embedding replaced Dynamic Data Exchange as the recommended model for inter program communication.
* Menu bar: Starting in Windows 7, the
Ribbon
A ribbon or riband is a thin band of material, typically cloth but also plastic or sometimes metal, used primarily as decorative binding and tying. Cloth ribbons are made of natural materials such as silk, cotton, and jute and of synthetic mater ...
interface is a recommended replacement for the menu bar and context menus. It is provided by the UIRibbon component.
Windows Ribbon Framework
/ref>
Developer experience
Windows USER implements abstractions that are used to build Windows applications. These include
* HWND (Handle to Window)
The HWND is the basic unit of visual display and input in the Windows developer platform. All visual elements either have their own HWNDs or live as part of a larger HWND. Many functions in Windows USER manipulate properties on HWNDs such as size, position and title. Each HWND also has a communication channel (WNDPROC - Window Procedure) for delivery of messages.
Windows are managed as a tree, with the desktop window at the root of the hierarchy. Child windows are usually (but not always) visually contained within their parents.
* MSG (Message)
Applications and the operating system communicate with HWNDs using messages. A window message is the combination of a target HWND, a message code, and other details such as mouse position.
* Message Loop
By combining calls to Windows USER in the right way, a Windows application processes messages. The core Windows message loop (including calls to GetMessage, TranslateMessage and DispatchMessage) is at the core of any Windows application.
Developer functionality related to Windows USER is provided in the C header file winuser.h.
Implementation
In 16-bit versions of Windows, Windows USER was implemented as a file called user.exe. The file extension here was a misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name ...
, as Windows USER was in fact always a dynamic link library.
In 32-bit versions of Windows, the 32-bit version of Windows USER is called user32.dll and is located in the System32 directory, while compatibility with 16-bit applications is provided by having a modified version of user.exe also present.
In 64-bit versions of Windows, the 64-bit implementation of Windows USER is called user32.dll and is located in the System32 directory, while a modified 32-bit version (also called user32.dll) is present in the SysWOW64 directory.
See also
* Graphics Device Interface (GDI)
* Microsoft Windows library files
References
External links
Comprehensive Reference on WOW64 Folders, Variables, Values and References
{{Windows Components
Windows NT architecture
Windows components
Windows technology