sdl/test/testdrawchessboard.c

/*
   Copyright (C) 1997-2024 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 the SDL render API */

/* This allows testing SDL_CreateSoftwareRenderer with the window surface API. Undefine it to use the accelerated renderer instead. */
#define USE_SOFTWARE_RENDERER

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

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

#include "SDL.h"

SDL_Window *window;
SDL_Renderer *renderer;
int done;

#ifdef USE_SOFTWARE_RENDERER
SDL_Surface *surface;
#endif

void DrawChessBoard(void)
{
    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(void)
{
    SDL_Event e;
    while (SDL_PollEvent(&e)) {

#ifdef USE_SOFTWARE_RENDERER
        /* 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);
        }
#endif

        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;
        }
    }

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

    DrawChessBoard();

    SDL_RenderPresent(renderer);

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

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;
    }
#ifdef USE_SOFTWARE_RENDERER
    surface = SDL_GetWindowSurface(window);
    renderer = SDL_CreateSoftwareRenderer(surface);
#else
    renderer = SDL_CreateRenderer(window, -1, 0);
#endif
    if (!renderer) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Render creation for surface fail : %s\n", SDL_GetError());
        return 1;
    }

    /* 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;
}