Windows USER

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Windows USER is a component of the Microsoft Windows operating system that provides core functionality for building simple user interfaces. Components already exist in all versions of Windows, and include functionality for window management, message delivery, input processing and standard control.

Video Windows USER

Functionality and roles

Windows USER provides most of the core user experience for Microsoft Windows. Historically, it is responsible for:

• Causes the window to be drawn (using GDI as a free-tool API for drawing primitives)
• Blur over an overlapping window behind another
• The size and positioning of windows
• Provides all standard window management controls (such as a close box or title bar)
• Provides a standard Windows menu bar
• Provides standard controls (such as buttons, List boxes or Edit Boxes)
• Provides management dialog box (shortcut key, tab key processing)
• Process all user input from mouse and keyboard
• Desktop background image
• Drawing all standard visual elements
• Communication between processes using Dynamic Data Exchange
• The mouse pointer shows the cursor and management
• Data transfer (Clipboard)

Gradually, as Windows has become bigger and better the factor, Windows USER has been working with other components to provide this functionality:

• Controls: Starting with Windows 95, new controls are placed into separate general control components. Starting with Windows XP, a new implementation of the standard control is also moved to the same component.
• Windows Management Experience: Starting with Windows Vista, a standard windows management image is moved from Windows USER to the Desktop Window Manager.
• Visual Standard: Starting with Windows XP, visual elements are drawn by the Theming component.
• Communication between programs: Started with Windows 3.1, Object Linking and Embedding replacing Dynamic Data Exchange as the recommended model for communication between programs.
• Menu bar: Starting in Windows 7, the Ribbon interface is the recommended substitute for the menu bar and context menu. This is provided by the UIRibbon component.

Maps Windows USER

Developer experience

Windows USER implements the abstractions used to build Windows applications. This includes

• HWND (Handles to Window)

HWND is the basic unit of visual display and input on the Windows developer platform. All visual elements have their own HWND or live as part of a larger HWND. Many functions in Windows USER manipulate properties in HWND such as size, position, and title. Each HWND also has a communication channel (WNDPROC - Window Procedure) for message delivery.

Windows is managed as a tree, with a desktop window at the root of the hierarchy. Child windows are usually (but not always) visually contained in their parents.

• MSG (Message)

Applications and operating systems communicate with HWND using messages. The window message is a combination of the HWND target, the message code, and other details such as the position of the mouse.

• Message Circles

By merging calls to Windows USER the right way, Windows applications process messages. The Windows message loop core (including calls to GetMessage, TranslateMessage and DispatchMessage) is the core of any Windows application.

The developer function associated with Windows USER is provided in the C winuser.h header file.

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Implementation

In the 16-bit version of Windows, Windows USER is implemented as a file called user.exe. The file extension here is a misnomer, because the USER of Windows is in fact always a dynamic link library.

On 32-bit versions of Windows, 32-bit versions of Windows Users are called user32.dll and are 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 Windows USER implementation is called user32.dll and is located in the System32 directory, while the modified 32-bit version (also called user32.dll) exists in the SysWOW64 directory.

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See also

• Graphical Device Interface (GDI)
• Microsoft Windows libraries file

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References

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External links

• API call list - USER32.DLL - Tips for using the User API Client Library with Visual Basic
• Complete Reference of Folder, Variables, Value, and Reference WOW64

Source of the article : Wikipedia