Microwindows is a windowing system

Windowing system

A windowing system is a component of a graphical user interface , and more specifically of a desktop environment, which supports the implementation of window managers, and provides basic support for graphics hardware, pointing devices such as mice, and keyboards...

 which is full featured enough to be used on a PC

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

 or a PDA

PDA

A PDA is most commonly a Personal digital assistant, also known as a Personal data assistant, a mobile electronic device.PDA may also refer to:In science, medicine and technology:...

. The Nano-X Window System is an Open Source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 project aimed at bringing the features of modern graphical windowing environments to smaller devices and platforms. The project was renamed to Nano-X Window System, due to legal threats from Microsoft regarding the Windows

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 trademark.

Overview

Nano-X's origin is with NanoGUI. NanoGUI was created by Alex Holden by taking David Bell's mini-X server and Alan Cox's modifications and adding client/server networking. Gregory Haerr then took interest in the NanoGUI project and began making extensive enhancements and modifications to NanoGUI. Around version 0.5, Gregory Haerr

Gregory Haerr

Gregory Haerr is an American entrepreneur and the founder and CEO of Century Software, a provider of Windows and Linux based terminal emulation software. Haerr founded the company in 1982, after having moved from his hometown of La Jolla to Salt Lake City in 1981. Haerr is the oldest of seven...

 added support for multiple API's, and began distributing Microwindows. In Microwindows 0.84, all previous NanoGUI changes were incorporated and since then has been the combined NanoGUI/Microwindows distribution. In January 2005, the system changed its name to the Nano-X Window System, with a planned first release as v0.91.

Technical

The Nano-X Window System is extremely portable, and completely written in C

C (programming language)

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....

, although some routines have been recoded in assembly for speed. It has been ported to the Intel 16 and 32 bit cpu's, as well as MIPS R4000 (NEC Vr41xx) StrongARM

StrongARM

The StrongARM is a family of microprocessors that implemented the ARM V4 instruction set architecture . It was developed by Digital Equipment Corporation and later sold to Intel, who continued to manufacture it before replacing it with the XScale....

 and PowerPC

PowerPC

PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...

 chips found on popular handheld and pocket PC's. There have been rumors of an SH3 port as well.

The Nano-X Window System currently runs on 32-bit

32-bit

The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....

 Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 systems with kernel framebuffer support, or through the popular SVGAlib library. In addition, it has been ported to 16-bit

16-bit

-16-bit architecture:The HP BPC, introduced in 1975, was the world's first 16-bit microprocessor. Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816. The Intel 8088 was program-compatible with the Intel 8086, and was 16-bit in that its registers were 16...

 Linux ELKS, and real mode

Real mode

Real mode, also called real address mode, is an operating mode of 80286 and later x86-compatible CPUs. Real mode is characterized by a 20 bit segmented memory address space and unlimited direct software access to all memory, I/O addresses and peripheral hardware...

 MS-DOS

MS-DOS

MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

. Microwindows screen drivers for 1, 2, 4, 8, 16 and 32 bits-per-pixel have been written, as well as a VGA

Video Graphics Array

Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...

 16 color 4 planes driver.

Recently, an X11 driver was completed that allows Microwindows applications to be run on top of the X Window desktop. This driver emulates all of Microwindows' truecolor and palette modes so that an application can be previewed using the target system's display characteristics directly on the desktop display, regardless of the desktop display characteristics.

Layered Design

Microwindows is essentially a layered design that allows different layers to be used or rewritten to suit the needs of the implementation. At the lowest level, screen, mouse

Mouse (computing)

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...

/touchpad

Touchpad

A touchpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on screen. Touch pads are a common feature of laptop computers, and they are also used as a substitute for a mouse where desk...

 and keyboard

Keyboard (computing)

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

 drivers provide access to the actual display

Computer display

A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

 and other user-input hardware. At the mid level, a portable graphics engine is implemented, providing support for line draws, area fills, polygons, clipping and color models. At the upper level, various API's are implemented providing access to the graphics applications programmer. These APIs may or may not provide desktop and/or window look and feel. Currently, Microwindows supports the Windows Win32/WinCE GDI

Graphics Device Interface

The Graphics Device Interface is a Microsoft Windows application programming interface and core operating system component responsible for representing graphical objects and transmitting them to output devices such as monitors and printers....

 and Nano-X APIs. These APIs provide close compatibility with the Win32 and X Window systems, allowing programs to be ported from other systems easily.

Device Drivers

The device driver interfaces are defined in device.h. A given implementation of Microwindows will link at least one screen, mouse and keyboard driver into the system. The mid level routines in the device-independent graphics engine core then call the device driver directly to perform the hardware-specific operations. This setup allows varying hardware devices to be added to the Microwindows system without affecting the way the entire system works.

Application programmer interfaces

Microwindows currently supports two different application programming interface

Application programming interface

An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...

s (APIs). This set of routines handles client

Client (computing)

A client is an application or system that accesses a service made available by a server. The server is often on another computer system, in which case the client accesses the service by way of a network....

–server

Server (computing)

In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

 activity, window manager

Window manager

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...

activities like drawing title bars, close boxes, etc, as well as handling the programmer's requests for graphics output. Both the APIs run on top of the core graphics engine routines and device drivers.

The basic model of any API on top of Microwindows is to initialize the screen, keyboard and mouse drivers, then hang in a select loop waiting for an event. When an event occurs, if it is a system event like keyboard or mouse activity, then this information is passed to the user program converted to an expose event, paint message, etc. If it is a user requesting a graphics operation, then the parameters are decoded and passed to the appropriate GdXXX engine routine. Note that the concept of a window versus raw graphics operations is handled at this API level. That is, the API defines the concepts of what a window is, what the coordinate systems are, etc, and then the coordinates are all converted to "screen coordinates" and passed to the core GdXXX engine routines to do the real work. This level also defines graphics or display contexts and passes that information, including clipping information, to the core engine routines.

Microwindows API

The Microwindows API tries to be compliant with the Microsoft Win32 and WinCE GDI standard. Currently, there is support for most of the graphics drawing and clipping routines, as well as automatic window title bar drawing and dragging windows for movement. The Microwindows API is message-based, and allows programs to be written without regard to the eventual window management policies implemented by the system. The Microwindows API is not currently client/server, and will be discussed in more detail in section 4.

Nano-X API

The Nano-X API is modeled after the mini-x server written initially by David Bell, which was a reimplementation of X on the MINIX operating system. It loosely follows the X Window System Xlib API, but the names all being with GrXXX rather than X.... Currently, the Nano-X API is client/server, but does not have any provisions for automatic window dressings, title bars, or user window moves. There are several groups writing widget sets currently, which will provide such things. The user programs must also then write only to a specific widget set API, rather than using the Nano-X API directly, which means that only the functionality provided by the widget set will be upwardly available to the applications programmer. (Although this could be considerable, in the case that, say Gdk was ported.)

Microwindows API

The fundamental communications mechanism in the Microwindows API is the message. A message consists of a well-known message number, and two parameters, known as wParam and lParam. Messages are stored in an application's message-queue, and retrieved via the GetMessage function. The application blocks while waiting for a message. There are messages that correspond to hardware events, like WM_CHAR for keyboard input or WM_LBUTTONDOWN for mouse button down. In addition, events signaling window creation and destruction WM_CREATE and WM_DESTROY are sent. In most cases, a message is associated with a window, identified as an HWND. After retrieving the message, the application sends the message to the associated window's handling procedure using DispatchMessage. When a window class is created, its associated message handling procedure is specified, so the system knows where to send the message.

The message-passing architecture allows the core API to manage many system functions by sending messages on all sorts of events, like window creation, painting needed, moving, etc. By default, the associated window handling function gets a "first pass" at the message, and then calls the DefWindowProc function, which handles default actions for all the messages. In this way, all windows can behave the same way when dragged, etc, unless specifically overridden by the user. Major window management policies can be redefined by merely re-implementing DefWindowProc, rather than making changes throughout the system.

Window creation and destruction

The basic unit of screen organization in Microwindows API is the window. Windows describe an area of the screen to draw onto, as well as an associate "window procedure" for handling messages destined for this window. Applications programmers can create windows from pre-defined classes, like buttons, edit boxes, and the like, or define their own window classes. In both cases, the method of creating and communicating with the windows remains exactly the same. The following functions deal with window registration, creation, and destruction: