SDL2 est un blibliothèque qui permet de développer des applications graphiques, comme de jeux 2D. Un des points fort de SDL2 est incontestablement sa simplicité et sa portabilité sous Android !

• https://wiki.libsdl.org/
• https://www.libsdl.org/projects/SDL_ttf/
• https://www.libsdl.org/projects/SDL_image/

Notre coquille se compose de trois fichiers : model.c, model_func.h et model_func.c. Le fichier model.c contient le programme principal (fonction main()) qui s'appuie sur quatre fonctions abstraites définies dans le module model_func.h & model_func.c :

• init() : …
• render() : …
• process() : …
• clean() : …

Voici le code de cette coquille :

model.c

// SDL2 Demo by aurelien.esnard@u-bordeaux.fr
 
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>  // required to load transparent texture from PNG
#include <SDL2/SDL_ttf.h>    // required to use TTF fonts     
#include <stdio.h>
#include <stdbool.h>
#include "model_func.h"
 
/* **************************************************************** */
 
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
 
/* **************************************************************** */
 
int main(int argc, char * argv[])
{ 
  /* initialize SDL2 and some extensions */
  if(SDL_Init(SDL_INIT_VIDEO) != 0) ERROR("SDL_Init VIDEO"); 
  if(IMG_Init(IMG_INIT_PNG & IMG_INIT_PNG) != IMG_INIT_PNG) ERROR("IMG_Init PNG");
  if(TTF_Init() != 0) ERROR("TTF_Init");  
 
  /* create window and renderer */
  SDL_Window * win = SDL_CreateWindow("Hello World!", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
    				      SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
  if(!win) ERROR("SDL_CreateWindow");  
  SDL_Renderer * ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
  if(!ren) ERROR("SDL_CreateWindow");    
 
  /* initialize your environment */
  Env * env = init(win, ren);
 
  /* main render loop */
  bool quit = false;
  while (!quit) {
 
    /* manage events */
    SDL_Event e;
    while (SDL_PollEvent(&e)) {
      /* process your events */
      quit = process(win, ren, env, &e);
      if(quit) break;
    }
 
    /* background in gray */
    SDL_SetRenderDrawColor(ren, 0xA0, 0xA0, 0xA0, 0xFF); 
    SDL_RenderClear(ren);
 
    /* render all what you want */    
    render(win, ren, env); 
    SDL_RenderPresent(ren);
    SDL_Delay(10);
  }
 
  /* clean your environment */
  clean(win, ren, env);
 
  SDL_DestroyRenderer(ren);
  SDL_DestroyWindow(win);
  IMG_Quit();
  TTF_Quit();  
  SDL_Quit();
 
  return EXIT_SUCCESS;
}

model_func.h

// SDL2 Demo by aurelien.esnard@u-bordeaux.fr
 
#ifndef MODEL_FUNC_H
#define MODEL_FUNC_H
 
#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdbool.h>
 
typedef struct Env_t Env;
 
/* **************************************************************** */
 
#ifdef __ANDROID__ 
#define PRINT(STR, ...) do { SDL_Log(STR, ##__VA_ARGS__);  } while(0)
#define ERROR(STR, ...) do { SDL_Log(STR, ##__VA_ARGS__); exit(EXIT_FAILURE); } while(0) 
// #define LOG(TAG, STR, ...) __android_log_print(ANDROID_LOG_VERBOSE, TAG ,STR, ##__VA_ARGS__)
# else
#define PRINT(STR, ...) do { printf(STR, ##__VA_ARGS__); } while(0)
#define ERROR(STR, ...) do { fprintf(stderr, STR, ##__VA_ARGS__); exit(EXIT_FAILURE); } while(0)
#endif
 
/* **************************************************************** */
 
Env * init(SDL_Window* win, SDL_Renderer* ren);
void render(SDL_Window* win, SDL_Renderer* ren, Env * env);
void clean(SDL_Window* win, SDL_Renderer* ren, Env * env);
bool process(SDL_Window* win, SDL_Renderer* ren, Env * env, SDL_Event * e);
 
/* **************************************************************** */
 
#endif

model_func.c

// SDL2 Demo by aurelien.esnard@u-bordeaux.fr
 
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>  // required to load transparent texture from PNG
#include <SDL2/SDL_ttf.h>    // required to use TTF fonts     
 
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "model_func.h"
 
/* **************************************************************** */
 
struct Env_t {  
 
  /* PUT YOUR VARIABLES HERE */
 
}; 
 
/* **************************************************************** */
 
Env * init(SDL_Window* win, SDL_Renderer* ren)
{  
  Env * env = malloc(sizeof(struct Env_t));
 
  /* PUT YOUR CODE HERE TO INIT TEXTURES, ... */
 
  return env;
}
 
/* **************************************************************** */
 
void render(SDL_Window* win, SDL_Renderer* ren, Env * env)
{
  /* PUT YOUR CODE HERE TO RENDER TEXTURES, ... */
}
 
/* **************************************************************** */
 
 
bool process(SDL_Window* win, SDL_Renderer* ren, Env * env, SDL_Event * e)
{     
 
  if (e->type == SDL_QUIT) {
    return true;
  }
 
  /* PUT YOUR CODE HERE TO PROCESS EVENTS */
 
  return false; 
}
 
/* **************************************************************** */
 
void clean(SDL_Window* win, SDL_Renderer* ren, Env * env)
{
  /* PUT YOUR CODE HERE TO CLEAN MEMORY */
 
  free(env);
}     

Pour illustrer notre petite coquille, voici une petite démo qui montre les différentes possibilités de SDL2 (texte TTF, texture transparente PNG, …). Vous trouverez tout cela dans l'archive : sdl2-demo.zip. Lire le README.txt pour démarrer.

Pour compiler :

gcc -std=c99 -O3 -Wall -c -o demo.o demo.c
gcc -rdynamic -lm -lSDL2 -lSDL2_ttf -lSDL2_image demo.o -o demo

Attention, vous devez satisfaire quelques dépendances. Sous Debian :

sudo apt-get install libsdl2-dev libsdl2-image-dev  libsdl2-ttf-dev

coming soon!