SDL/test/testdrawchessboard.c

/*
   Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely.

   This file is created by : Nitin Jain (nitin.j4@samsung.com)
*/

/* Sample program:  Draw a Chess Board  by using SDL_CreateSoftwareRenderer API */

#include <stdlib.h>
#include <stdio.h>

#ifdef __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#endif

#include "SDL.h"

SDL_Window *window;
SDL_Renderer *renderer;
SDL_Surface *surface;
int done;

void
DrawChessBoard()
{
    int row = 0,column = 0,x = 0;
    SDL_Rect rect, darea;

    /* Get the Size of drawing surface */
    SDL_RenderGetViewport(renderer, &darea);

    for( ; row < 8; row++)
    {
        column = row%2;
        x = column;
        for( ; column < 4+(row%2); column++)
        {
            SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0xFF);

            rect.w = darea.w/8;
            rect.h = darea.h/8;
            rect.x = x * rect.w;
            rect.y = row * rect.h;
            x = x + 2;
            SDL_RenderFillRect(renderer, &rect);
        }
    }
}

void
loop()
{
    SDL_Event e;
    while (SDL_PollEvent(&e)) {
       
       /* Re-create when window has been resized */
       if ((e.type == SDL_WINDOWEVENT) && (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)) {

          SDL_DestroyRenderer(renderer);

          surface = SDL_GetWindowSurface(window);
          renderer = SDL_CreateSoftwareRenderer(surface);
          /* Clear the rendering surface with the specified color */
          SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
          SDL_RenderClear(renderer);
       }

       if (e.type == SDL_QUIT) {
            done = 1;
#ifdef __EMSCRIPTEN__
            emscripten_cancel_main_loop();
#endif
            return;
        }

        if ((e.type == SDL_KEYDOWN) && (e.key.keysym.sym == SDLK_ESCAPE)) {
            done = 1;
#ifdef __EMSCRIPTEN__
            emscripten_cancel_main_loop();
#endif
            return;
        }
    }

    DrawChessBoard();

    /* Got everything on rendering surface,
       now Update the drawing image on window screen */
    SDL_UpdateWindowSurface(window);
}

int
main(int argc, char *argv[])
{
    /* Enable standard application logging */
    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);

    /* Initialize SDL */
    if(SDL_Init(SDL_INIT_VIDEO) != 0)
    {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_Init fail : %s\n", SDL_GetError());
        return 1;
    }


    /* Create window and renderer for given surface */
    window = SDL_CreateWindow("Chess Board", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_RESIZABLE);
    if(!window)
    {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Window creation fail : %s\n",SDL_GetError());
        return 1;
    }
    surface = SDL_GetWindowSurface(window);
    renderer = SDL_CreateSoftwareRenderer(surface);
    if(!renderer)
    {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Render creation for surface fail : %s\n",SDL_GetError());
        return 1;
    }

    /* Clear the rendering surface with the specified color */
    SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
    SDL_RenderClear(renderer);


    /* Draw the Image on rendering surface */
    done = 0;
#ifdef __EMSCRIPTEN__
    emscripten_set_main_loop(loop, 0, 1);
#else
    while (!done) {
        loop();
    }
#endif

    SDL_Quit();
    return 0;
}