Introduction to SDL 2.0

1. Introduction to SDL

1.1. What is SDL?

The Simple DirectMedia Layer library (SDL) is a general API that provides low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D framebuffer across multiple platforms.

The current version supports Windows XP/Vista/7/8, Mac OS X, Linux, iOS, and Android. The code contains support for other operating systems but those are not officially supported.

• For the latest information on what is supported see http://hg.libsdl.org/SDL/file/default/README-platforms.txt

SDL is written in C, but works with C++ natively, and has bindings to several other languages, including Ada, C#, Eiffel, Erlang, Euphoria, Guile, Haskell, Java, Lisp, Lua, ML, Objective C, Pascal, Perl, PHP, Pike, Pliant, Python, Ruby, and Smalltalk.

• For the latest list of languages see http://www.libsdl.org/languages.php

SDL 2.0 is under the zlib license, which allows free use for commercial and non-commercial purposes.

1.2. What can SDL do?

Video

• Set a video mode at any depth (8-bpp or greater) with optional conversion, if the video mode is not supported by the hardware
• Write directly to a linear graphics framebuffer
• Create surfaces with color key or alpha blending attributes
• Surface blits are automatically converted to the target format using optimized blitters and are hardware accelerated, when possible. MMX optimized blits are available for the x86
• Hardware accelerated blit and fill operations are used if supported by the hardware
• Window Management
• Rendering
• OpenGL API support for 3D games and engines

Input Events

• Events provided for:
  • Application visibility changes
  • Keyboard input
  • Mouse input
  • Joystick input
  • User-requested quit

• Each event can be enabled or disabled with SDL_EventState()

• Events are passed through a user-specified filter function before being posted to the internal event queue
• Thread-safe event queue

Force Feedback

• Force feedback is supported under Windows, Mac OS X and Linux

Audio

• Set audio playback of 8-bit and 16-bit audio, mono or stereo, with optional conversion if the format is not supported by the hardware
• Audio runs independently in a separate thread, filled via a user callback mechanism
• Designed for custom software audio mixers, but the example archive contains a complete audio/music output library

File I/O Abstraction

• General purpose abstraction for opening, reading and writing data
• Built-in support for files and memory

Shared Object Support

• Load shared objects (DLL on Windows, .dylib on Mac OS X, .so on Linux)
• Lookup functions in shared objects

Threads

• Simple thread creation API
• Simple thread local storage API
• Simple binary semaphores for synchronization

Timers

• Get the number of milliseconds elapsed
• Wait a specified number of milliseconds
• Set a single periodic timer with 10ms resolution

CPU Feature Detection

• Detect MMX, SSE, 3DNow and AltiVec CPU features

Endian Independence

• Detect the endianness of the current system
• Routines for fast swapping of data values
• Read and write data of a specified endianness

Power Management

• Querying power management status

1.3. What platforms does SDL run on?

Windows

• Two versions, one safe for all systems based on Win32 APIs, and one with higher performance, based on DirectX APIs
• Safe version uses GDI for video display. High performance version uses Direct3D for video display, taking advantage of modern hardware acceleration

• Safe version uses waveOut APIs for sound. High performance version uses DirectSound for audio playback

Mac OS X

• Uses Cocoa for video display, taking advantage of OpenGL for hardware acceleration
• Uses Core Audio for sound

Linux

• Uses X11 for video display, taking advantage of OpenGL for hardware acceleration

• Uses the ALSA, OSS and PulseAudio APIs for sound

iOS

• Uses UIKit for video display, taking advantage of OpenGL ES 2.0 for hardware acceleration
• Uses Core Audio for sound

Android

• Uses JNI interfaces for video display, taking advantage of OpenGL ES 1.1 and 2.0 for hardware acceleration
• Uses JNI audio callbacks for sound

2. Special features in SDL 2.0

• Full 3D hardware acceleration
• Support for OpenGL 3.0+
• Support for multiple windows
• Support for multiple displays
• Support for multiple mice, tablets, etc.
• Force Feedback available on Windows, Mac OS X and Linux

2.1. Transitioning from SDL 1.2 to 2.0

• Migration Guide