/*
  Copyright (C) 1997-2011 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.
*/

/* Simple program:  Fill a colormap with gray and stripe it down the screen */

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

#include "SDL.h"

#ifdef TEST_VGA16               /* Define this if you want to test VGA 16-color video modes */
#define NUM_COLORS	16
#else
#define NUM_COLORS	256
#endif

/* Draw a randomly sized and colored box centered about (X,Y) */
void
DrawBox(SDL_Surface * screen, int X, int Y, int width, int height)
{
    static unsigned int seeded = 0;
    SDL_Rect area;
    Uint32 color;
    Uint32 randc;

    /* Seed the random number generator */
    if (seeded == 0) {
        srand((unsigned int)time(NULL));
        seeded = 1;
    }

    /* Get the bounds of the rectangle */
    area.w = (rand() % width);
    area.h = (rand() % height);
    area.x = X - (area.w / 2);
    area.y = Y - (area.h / 2);
    randc = (rand() % NUM_COLORS);

    if (screen->format->BytesPerPixel == 1) {
        color = randc;
    } else {
        color = SDL_MapRGB(screen->format, randc, randc, randc);
    }

    /* Do it! */
    SDL_FillRect(screen, &area, color);
    if (screen->flags & SDL_DOUBLEBUF) {
        SDL_Flip(screen);
    } else {
        SDL_UpdateRects(screen, 1, &area);
    }
}

void
DrawBackground(SDL_Surface * screen)
{
    int i, j, k;
    Uint8 *buffer;
    Uint16 *buffer16;
    Uint16 color;
    Uint8 gradient;

    /* Set the surface pixels and refresh! */
    /* Use two loops in case the surface is double-buffered (both sides) */

    for (j = 0; j < 2; ++j) {
        if (SDL_LockSurface(screen) < 0) {
            fprintf(stderr, "Couldn't lock display surface: %s\n",
                    SDL_GetError());
            return;
        }
        buffer = (Uint8 *) screen->pixels;

        if (screen->format->BytesPerPixel != 2) {
            for (i = 0; i < screen->h; ++i) {
                memset(buffer, (i * (NUM_COLORS - 1)) / screen->h,
                       screen->w * screen->format->BytesPerPixel);
                buffer += screen->pitch;
            }
        } else {
            for (i = 0; i < screen->h; ++i) {
                gradient = ((i * (NUM_COLORS - 1)) / screen->h);
                color =
                    SDL_MapRGB(screen->format, gradient, gradient, gradient);
                buffer16 = (Uint16 *) buffer;
                for (k = 0; k < screen->w; k++) {
                    *(buffer16 + k) = color;
                }
                buffer += screen->pitch;
            }
        }

        SDL_UnlockSurface(screen);
        if (screen->flags & SDL_DOUBLEBUF) {
            SDL_Flip(screen);
        } else {
            SDL_UpdateRect(screen, 0, 0, 0, 0);
            break;
        }
    }
}

SDL_Surface *
CreateScreen(Uint16 w, Uint16 h, Uint8 bpp, Uint32 flags)
{
    SDL_Surface *screen;
    int i;
    SDL_Color palette[NUM_COLORS];

    /* Set the video mode */
    screen = SDL_SetVideoMode(w, h, bpp, flags);
    if (screen == NULL) {
        fprintf(stderr, "Couldn't set display mode: %s\n", SDL_GetError());
        return (NULL);
    }
    fprintf(stderr, "Screen is in %s mode\n",
            (screen->flags & SDL_FULLSCREEN) ? "fullscreen" : "windowed");

    if (bpp == 8) {
        /* Set a gray colormap, reverse order from white to black */
        for (i = 0; i < NUM_COLORS; ++i) {
            palette[i].r = (NUM_COLORS - 1) - i * (256 / NUM_COLORS);
            palette[i].g = (NUM_COLORS - 1) - i * (256 / NUM_COLORS);
            palette[i].b = (NUM_COLORS - 1) - i * (256 / NUM_COLORS);
        }
        SDL_SetColors(screen, palette, 0, NUM_COLORS);
    }

    return (screen);
}

int
main(int argc, char *argv[])
{
    SDL_Surface *screen;
    Uint32 videoflags;
    int done;
    SDL_Event event;
    int width, height, bpp;

    /* Initialize SDL */
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
        exit(1);
    }

    /* See if we try to get a hardware colormap */
    width = 640;
    height = 480;
    bpp = 8;
    videoflags = SDL_SWSURFACE;
    while (argc > 1) {
        --argc;
        if (argv[argc - 1] && (strcmp(argv[argc - 1], "-width") == 0)) {
            width = atoi(argv[argc]);
            --argc;
        } else if (argv[argc - 1]
                   && (strcmp(argv[argc - 1], "-height") == 0)) {
            height = atoi(argv[argc]);
            --argc;
        } else if (argv[argc - 1] && (strcmp(argv[argc - 1], "-bpp") == 0)) {
            bpp = atoi(argv[argc]);
            --argc;
        } else if (argv[argc] && (strcmp(argv[argc], "-hw") == 0)) {
            videoflags |= SDL_HWSURFACE;
        } else if (argv[argc] && (strcmp(argv[argc], "-hwpalette") == 0)) {
            videoflags |= SDL_HWPALETTE;
        } else if (argv[argc] && (strcmp(argv[argc], "-flip") == 0)) {
            videoflags |= SDL_DOUBLEBUF;
        } else if (argv[argc] && (strcmp(argv[argc], "-noframe") == 0)) {
            videoflags |= SDL_NOFRAME;
        } else if (argv[argc] && (strcmp(argv[argc], "-resize") == 0)) {
            videoflags |= SDL_RESIZABLE;
        } else if (argv[argc] && (strcmp(argv[argc], "-fullscreen") == 0)) {
            videoflags |= SDL_FULLSCREEN;
        } else {
            fprintf(stderr,
                    "Usage: %s [-width] [-height] [-bpp] [-hw] [-hwpalette] [-flip] [-noframe] [-fullscreen] [-resize]\n",
                    argv[0]);
            exit(1);
        }
    }

    /* Set a video mode */
    screen = CreateScreen(width, height, bpp, videoflags);
    if (screen == NULL) {
        exit(2);
    }

    DrawBackground(screen);

    /* Wait for a keystroke */
    done = 0;
    while (!done && SDL_WaitEvent(&event)) {
        switch (event.type) {
        case SDL_MOUSEBUTTONDOWN:
            DrawBox(screen, event.button.x, event.button.y, width, height);
            break;
        case SDL_KEYDOWN:
            /* Ignore ALT-TAB for windows */
            if ((event.key.keysym.sym == SDLK_LALT) ||
                (event.key.keysym.sym == SDLK_TAB)) {
                break;
            }
            /* Center the mouse on <SPACE> */
            if (event.key.keysym.sym == SDLK_SPACE) {
                SDL_WarpMouse(width / 2, height / 2);
                break;
            }
            /* Toggle fullscreen mode on <RETURN> */
            if (event.key.keysym.sym == SDLK_RETURN) {
                videoflags ^= SDL_FULLSCREEN;
                screen = CreateScreen(screen->w, screen->h,
                                      screen->format->BitsPerPixel,
                                      videoflags);
                if (screen == NULL) {
                    fprintf(stderr, "Couldn't toggle fullscreen mode\n");
                    done = 1;
                }
                DrawBackground(screen);
                break;
            }
            /* Any other key quits the application... */
        case SDL_QUIT:
            done = 1;
            break;
        case SDL_VIDEOEXPOSE:
            DrawBackground(screen);
            break;
        case SDL_VIDEORESIZE:
            printf("Screen resized to %dx%d\n", event.resize.w,
                   event.resize.h);
            screen =
                CreateScreen(event.resize.w, event.resize.h,
                             screen->format->BitsPerPixel, videoflags);
            if (screen == NULL) {
                fprintf(stderr, "Couldn't resize video mode\n");
                done = 1;
            }
            DrawBackground(screen);
            break;
        default:
            break;
        }
    }
    SDL_Quit();
    return (0);
}