Simple DirectMedia Layer

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Simple DirectMedia Layer
File:Sdl-logo.png
Logo
Developer(s) Sam Lantinga
Stable release 1.2.14 / October 19, 2009; 136570991 ago
Written in C
Operating system Cross-platform
Type API
License GNU Lesser General Public License
Website http://www.libsdl.org/

Simple DirectMedia Layer (SDL) is a cross-platform, free and open source software multimedia library written in C that presents a simple interface to various platforms' graphics, sound, and input devices. Software developers use it to write computer games or other multimedia applications that can run on many operating systems including Windows, Mac OS X, Linux, the PSP, Syllable, Haiku/BeOS, OpenVMS, WebOS, MorphOS, AmigaOS, and AmigaOS 4. It manages video, events, digital audio, CD-ROM, sound, threads, shared object loading, networking and timers[1].

Contents

History

Sam Lantinga created the library, first releasing it in early 1998, while working for Loki Software. He got the idea while porting a Windows application to Macintosh. He then used SDL to port Doom to BeOS (see Doom source ports). Several other free libraries were developed to work alongside SDL, such as SMPEG and OpenAL.

The SDL library has bindings for almost every programming language, from the popular (C++, Perl, C, Python (through pygame), Pascal etc.) to the less known (such as Euphoria or Pliant). This, and the fact that it is open-source and licensed under the LGPL, make SDL a common choice for many multimedia applications.

SDL itself is very simple; it merely acts as a thin, cross-platform wrapper, providing support for 2D pixel operations, sound, file access, event handling, timing, threading, and more. It is often used to complement OpenGL by setting up the graphical output and providing mouse and keyboard input, which are beyond the scope of OpenGL.

The library is divided into several subsystems, namely the Video (handles both surface functions and OpenGL), Audio, CD-ROM, Joystick and Timer subsystems. Besides this basic, low-level support, there also are a few separate official libraries that provide some additional functionality. These comprise the "standard library", and are provided on the official website and included in the official documentation:

  • SDL_image - support for multiple image formats
  • SDL_mixer - complex audio functions, mainly for sound mixing
  • SDL_net - networking support
  • SDL_ttf - TrueType font rendering support
  • SDL_rtf - simple Rich Text Format rendering

SDL 1.3

SDL 1.3 is a major update to the SDL 1.2 codebase. It replaces several parts of the 1.2 API with more general support for multiple input and output options. Some feature additions include multiple window support, multiple input device support (many mice, many keyboards, etc.), hardware-accelerated 2D graphics, and better Unicode support.[1]

SDL 1.3 also introduces a new licensing option, whereby one can obtain a commercial license to allow closed-source static linking. This opens up possibilities for distribution on platforms that do not allow dynamic linking.

Architecture

File:SDL Layers.svg
Abstraction layers of several SDL platforms.

SDL has the word "layer" in its title because it is actually a wrapper around operating-system-specific functionality. The chief purpose of SDL is to provide a common framework for accessing this functionality.

Because of the way SDL is designed, a lot of the source code is split into separate modules for each operating system, in order to make calls to the underlying system. When SDL is compiled, the correct modules are selected for the target system.

On Microsoft Windows, SDL uses a windib backend by default. A DirectX backend is also available. Older versions of SDL used DirectX 5, but SDL 1.2 (the current stable release) requires DirectX 7 by default. Sam Lantinga has stated that he plans to use DirectX 8 in future SDL releases[2].

On X11 platforms, including Linux and OpenVMS, SDL uses Xlib to communicate with the X11 system for graphics and events.

On Mac OS X, SDL uses Quartz.

Syntax and subsystems

The syntax of SDL is function-based: all operations done in SDL are done by passing parameters to functions. Special structures are also used to store the specific information SDL needs to handle. There are a few different subsystems SDL categorizes its functions under:

  • The Video, events and threads subsystem - this provides functionality for video, multi-threading, and event handling.
  • The Audio subsystem - this provides audio functionality.
  • The Time subsystem
  • The Joystick subsystem
  • The CD-ROM subsystem

Gallery

Extensions

libsdl.org Library List

See also

References

External links

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