SDL library in C/C++ with examples

SDL is Simple DirectMedia Layer.It is a cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL and Direct3D.It can be used to make animations and video games.  

• It basically provides a set of APIs to interact with various devices like graphics hardware, audio, keyboard, mouse, etc.
• It is written in C programming language and works with C++ and various other languages like c# and python.

Installation on Linux ( For OS which uses the apt package manager eg : Ubuntu ):

1. Run command sudo apt-get update on your terminal.
2. Run command sudo apt-get install clang on your terminal.
3. Run command sudo apt-get install libsdl2-2.0-0 libsdl2-dbg libsdl2-dev libsdl2-image-2.0-0 libsdl2-image-dbg libsdl2-image-dev on your terminal.
4. We need to make a Makefile.So open a text editor of your choice and start writing the code below.

# A simple Makefile for compiling small SDL projects

# set the compiler
CC := clang

# set the compiler flags
CFLAGS := `sdl2-config --libs --cflags` -ggdb3 -O0 --std=c99 -Wall -lSDL2_image -lm
# add header files here
HDRS :=

# add source files here
SRCS := #file-name.c

# generate names of object files
OBJS := $(SRCS:.c=.o)

# name of executable
EXEC := #name your executable file

# default recipe
all: $(EXEC)
 
showfont: showfont.c Makefile
    $(CC) -o $@ $@.c $(CFLAGS) $(LIBS)

glfont: glfont.c Makefile
    $(CC) -o $@ $@.c $(CFLAGS) $(LIBS)

# recipe for building the final executable
$(EXEC): $(OBJS) $(HDRS) Makefile
    $(CC) -o $@ $(OBJS) $(CFLAGS)

# recipe for building object files
#$(OBJS): $(@:.o=.c) $(HDRS) Makefile
#    $(CC) -o $@ $(@:.o=.c) -c $(CFLAGS)

# recipe to clean the workspace
clean:
    rm -f $(EXEC) $(OBJS)

.PHONY: all clean

Header Files:

C++

// for initializing and shutdown functions
#include <SDL2/SDL.h>

// for rendering images and graphics on screen
#include <SDL2/SDL_image.h>

// for using SDL_Delay() functions
#include <SDL2/SDL_timer.h>

Initialization:

C++

#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_timer.h>

int main(int argc, char *argv[])
{

    // returns zero on success else non-zero
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        printf("error initializing SDL: %s\n", SDL_GetError());
    }
    SDL_Window* win = SDL_CreateWindow("GAME",
                                       SDL_WINDOWPOS_CENTERED,
                                       SDL_WINDOWPOS_CENTERED,
                                       1000, 1000, 0);
    while (1)
        ;

    return 0;
}

That will create a empty window on your screen.
Output:

We will write a simple program to explain rendering and I/O handling:

C++

#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_timer.h>

int main(int argc, char *argv[])
{

    // returns zero on success else non-zero
    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        printf("error initializing SDL: %s\n", SDL_GetError());
    }
    SDL_Window* win = SDL_CreateWindow("GAME", // creates a window
                                       SDL_WINDOWPOS_CENTERED,
                                       SDL_WINDOWPOS_CENTERED,
                                       1000, 1000, 0);

    // triggers the program that controls
    // your graphics hardware and sets flags
    Uint32 render_flags = SDL_RENDERER_ACCELERATED;

    // creates a renderer to render our images
    SDL_Renderer* rend = SDL_CreateRenderer(win, -1, render_flags);

    // creates a surface to load an image into the main memory
    SDL_Surface* surface;

    // please provide a path for your image
    surface = IMG_Load("path");

    // loads image to our graphics hardware memory.
    SDL_Texture* tex = SDL_CreateTextureFromSurface(rend, surface);

    // clears main-memory
    SDL_FreeSurface(surface);

    // let us control our image position
    // so that we can move it with our keyboard.
    SDL_Rect dest;

    // connects our texture with dest to control position
    SDL_QueryTexture(tex, NULL, NULL, &dest.w, &dest.h);

    // adjust height and width of our image box.
    dest.w /= 6;
    dest.h /= 6;

    // sets initial x-position of object
    dest.x = (1000 - dest.w) / 2;

    // sets initial y-position of object
    dest.y = (1000 - dest.h) / 2;

    // controls animation loop
    int close = 0;

    // speed of box
    int speed = 300;

    // animation loop
    while (!close) {
        SDL_Event event;

        // Events management
        while (SDL_PollEvent(&event)) {
            switch (event.type) {

            case SDL_QUIT:
                // handling of close button
                close = 1;
                break;

            case SDL_KEYDOWN:
                // keyboard API for key pressed
                switch (event.key.keysym.scancode) {
                case SDL_SCANCODE_W:
                case SDL_SCANCODE_UP:
                    dest.y -= speed / 30;
                    break;
                case SDL_SCANCODE_A:
                case SDL_SCANCODE_LEFT:
                    dest.x -= speed / 30;
                    break;
                case SDL_SCANCODE_S:
                case SDL_SCANCODE_DOWN:
                    dest.y += speed / 30;
                    break;
                case SDL_SCANCODE_D:
                case SDL_SCANCODE_RIGHT:
                    dest.x += speed / 30;
                    break;
                default:
                    break;
                }
            }
        }

        // right boundary
        if (dest.x + dest.w > 1000)
            dest.x = 1000 - dest.w;

        // left boundary
        if (dest.x < 0)
            dest.x = 0;

        // bottom boundary
        if (dest.y + dest.h > 1000)
            dest.y = 1000 - dest.h;

        // upper boundary
        if (dest.y < 0)
            dest.y = 0;

        // clears the screen
        SDL_RenderClear(rend);
        SDL_RenderCopy(rend, tex, NULL, &dest);

        // triggers the double buffers
        // for multiple rendering
        SDL_RenderPresent(rend);

        // calculates to 60 fps
        SDL_Delay(1000 / 60);
    }

    // destroy texture
    SDL_DestroyTexture(tex);

    // destroy renderer
    SDL_DestroyRenderer(rend);

    // destroy window
    SDL_DestroyWindow(win);

    // close SDL
    SDL_Quit();

    return 0;
}

That will render a image on the window which can be controlled via your keyboard up, down, left, right.
Output:

References: https://www.libsdl.org/, https://github.com/vivek9236/rocket_game