Example!

Here is an example emscripten/webassembly app made with this library. The corresponding source file can be found at this repo.

Thin?

minimal design changes

• don’t provide an OO framework
• follow Lisa Lippincott’s advice for wrapping C libraries

Design rules:

• SDL_ => sdl::
• IMG_ => sdl::img::
• Owning types
  • owning types are provided for Surface, Texture, Window, and Renderer in the sdl::unique namespace.
  • these are unique pointers with the correct deleters supplied
  • Functions that create an SDL object and return a pointer (SDL_CreateWindow) return unique:: types.

  SDL_CreateWindow returns a sdl::unique::Window

• no out parameters these are returned in a tuple or struct in the same order
• when in parameters are pointers to allow a null value, provide an additional overload taking std::optional by value

Constants

• these are either constants or old style enums (for or-ing together)
• they are put in namespaces corresponding to the underscored prefixes in the SDL constant’s name
• if they were named all uppercase, we downcase everything and keep the underscores otherwise casing is the same
• SDL_WINDOW_FULLSCREEN => sdl::window::fullscreen

Edge cases

• SDL_WINDOW_ constants live in namespace window_opts because there is already a Window type. Differing only by case is too tricky.
• SDL_PollEvent is split into two functions:
  • HasNextEvent() which checks if the event queue has more events
  • NextEvent() which returns an optional containing the next event or nullopt if there are no more
• SDL_WINDOWPOS_UNDEFINED => sdl::window::pos_undefined

Carrying out design rules

macros

• documented in the horrible macros file
• systematic changes are carried out through macros
• macros are prefixed with SDLRAII_
• private/implementation macros are postfixed with a trailing underscore
• macros are undefined at the end of each file

Specific macros

SDLRAII_THE_PREFIX

• this tells the preprocessor what prefix to append to get SDL’s name for something
• examples
  • #define SDLRAII_THE_PREFIX SDL_ for things that start with SDL_
  • #define SDLRAII_THE_PREFIX IMG_ for things that start with IMG_

SDLRAII_PUT_PREFIX(X)

• appends the aformentioned prefix to X

SDLRAII_DEFUNIQUE(name,destructor)

• subclasses std::unique_ptr (publicly)
• names it name
• sets the deleter to destructor
• sets the type to <prefix>_name

others

the rest provide a straightforward wrapping (either through using or a variadic template that forwards its arguments)

Dependencies

• boost preprocessor
• SDL2