# sdl2 - SDL2 library wrapper

The `sdl2` package is a `ctypes`-based wrapper around the SDL2 library. It wraps nearly all publicly accessible structures and functions of the SDL2 library to be accessible from Python code.

A detailed documentation about the behaviour of the different functions can found within the SDL2 documentation.

## Usage

You can use `sdl2` in nearly exactly the same way as you would do with the SDL library and C code.

A brief example in C code:

    #include <SDL.h>

    int main(int argc, char *argv[]) {
        int running;
        SDL_Window *window;
        SDL_Surface *windowsurface;
        SDL_Surface *image;
        SDL_Event event;

        SDL_Init(SDL_INIT_VIDEO);

        window = SDL_CreateWindow("Hello World",
                                  SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                  592, 460, SDL_WINDOW_SHOWN);
        windowsurface = SDL_GetWindowSurface(window);

        image = SDL_LoadBMP("exampleimage.bmp");
        SDL_BlitSurface(image, NULL, windowsurface, NULL);

        SDL_UpdateWindowSurface(window);
        SDL_FreeSurface(image);

        running = 1;
        while (running) {
            while (SDL_PollEvent(&event) != 0) {
                if (event.type == SDL_QUIT) {
                    running = 0;
                    break;
                }
            }
        }
        SDL_DestroyWindow(window);
        SDL_Quit();
        return 0;
     }

Doing the same in Python:

    import sys
    import ctypes
    from sdl2 import *

    def main():
        SDL_Init(SDL_INIT_VIDEO)
        window = SDL_CreateWindow(b"Hello World",
                                  SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                  592, 460, SDL_WINDOW_SHOWN)
        windowsurface = SDL_GetWindowSurface(window)

        image = SDL_LoadBMP(b"exampleimage.bmp")
        SDL_BlitSurface(image, None, windowsurface, None)

        SDL_UpdateWindowSurface(window)
        SDL_FreeSurface(image)

        running = True
        event = SDL_Event()
        while running:
            while SDL_PollEvent(ctypes.byref(event)) != 0:
                if event.type == SDL_QUIT:
                    running = False
                    break

        SDL_DestroyWindow(window)
        SDL_Quit()
        return 0

    if __name__ == "__main__":
        sys.exit(main())

You can port code in a straightforward manner from one language to the other, though it is important to know about the limitations and slight differences mentioned below. Also, PySDL2 offers advanced functionality, which also feels more ‘pythonic’, via the `sdl2.ext` package.

## Missing interfaces

The following functions, classes, constants and macros of SDL2 are not available within `sdl2`.

- `SDL_REVISION` and `SDL_REVISION_NUMBER` from `SDL_revision.h`
- `SDL_NAME()` from `SDL_name.h`
- `SDL_MostSignificantBitIndex32()` from `SDL_bits.h`
- Everything from `SDL_main.h`
- Everything from `SDL_system.h`
- Everything from `SDL_assert.h`
- Everything from `SDL_thread.h`
- Everything from `SDL_atomic.h`
- Everything from `SDL_opengl.h`
- Everything from `SDL_mutex.h`

## Additional interfaces

The following functions, classes, constants and macros are are not part of SDL2, but were introduced by `sdl2`.

`sdl2.``ALL_PIXELFORMATS`

  Tuple containing all SDL2 pixel format constants (SDL_PIXELFORMAT_INDEX1LSB, ..., SDL_PIXELFORMAT_RGB565, ...).

`sdl2.``AUDIO_FORMATS`

  Set containing all SDL2 audio format constants (AUDIO_U8, AUDIO_S8, ... AUDIO_F32LSB, ... ).

`sdl2.``rw_from_object`(obj : object) → SDL_RWops

  Creates a SDL_RWops from any Python object. The Python object must at least support the following methods:

  read(length) -> data

  > length is the size in bytes to be read. A call to len(data) must return the correct amount of bytes for the data, so that len(data) / [size in bytes for a single element from data] returns the amount of elements. Must raise an error on failure.

  seek(offset, whence) -> int

  > offset denotes the offset to move the read/write pointer of the object to. whence indicates the movement behaviour and can be one of the following values:

  > - RW_SEEK_SET - move to offset from the start of the file
  > - RW_SEEK_CUR - move by offset from the relative location
  > - RW_SEEK_END - move to offset from the end of the file

  > If it could not move read/write pointer to the desired location, an error must be raised.

  tell() -> int

  > Must return the current offset. This method must only be provided, if seek() does not return any value.

  close() -> None

  > Closes the object(or its internal data access methods). Must raise an error on failure.

  write(data) -> None

  > Writes the passed data(which is a string of bytes) to the object. Must raise an error on failure.

  > Note

  > The write() method is optional and only necessary, if the passed object should be able to write data.

  The returned `sdl2.SDL_RWops` is a pure Python object and must not be freed via `sdl2.SDL_FreeRW()`.