Simple program to explain SDL rendering

SDL stands for Simple DirectMedia Layer library. SDL is a cross-platform graphics library that provides low-level access to graphics, audio, keyboard hardware via OpenGL and Direct3D. SDL is well-ported to Windows, Mac OS, Linux, Android, and iOS. 

SDL is written in C, works with minimal effort with C++, also there are many bindings available for other languages like C#.

Simple SDL program example to explain rendering and keyboard handling

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

int main() 
{ 

	// retutns 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("SDL Example", // 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 annimation loop 
	int close = 0; 

	// speed of box 
	int speed = 300; 

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

		// Events mangement 
		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; 
				} 
			} 
		} 

		// 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); 
	return 0; 
} 

 Read more: SDL tutorials