/****** sdl_extra.c
  sdl_extra.c/.h contain extra functions, structs, etc. that expand basic SDL functionality, such as pixel manipulation or surface scaling.
******/
#include "interface.h"
#include "sdl_extra.h"

SDL_Surface *SDL_ScaleSurface(SDL_Surface *surface, float scale_x, float scale_y) {
  long x;
  long y;
  long output_x;
  long output_y;
  long new_width = (long)((float)surface->w * scale_x+0.5f);
  long new_height = (long)((float)surface->h * scale_y+0.5f);
  SDL_Surface *new_surface = SDL_CreateRGBSurface(surface->flags, new_width, new_height, surface->format->BitsPerPixel, surface->format->Rmask, surface->format->Gmask, surface->format->Bmask, surface->format->Amask);

  for (y = 0;y < surface->h;y++) {
    for (x = 0;x < surface->w;x++) {
      for (output_y = 0;output_y < scale_y; ++output_y) {
        for (output_x = 0;output_x < scale_x; ++output_x) {
          putpixel(new_surface, (Sint32)(scale_x*x) + output_x, (Sint32)(scale_y*y)+output_y, getpixel(surface, x, y));
        }
      }
    }
  }
  return new_surface;
}

Uint32 getpixel(SDL_Surface *surface, int x, int y) {
  if (y >= 0 && x >= 0 && x <= surface->w && y <= surface->h) {
    int bpp = surface->format->BytesPerPixel;
    /* Here p is the address to the pixel we want to retrieve */
    Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;

    switch(bpp) {
    case 1:
        return *p;
        break;

    case 2:
        return *(Uint16 *)p;
        break;

    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
            return p[0] << 16 | p[1] << 8 | p[2];
        else
            return p[0] | p[1] << 8 | p[2] << 16;
        break;

    case 4:
        return *(Uint32 *)p;
        break;

    default:
        return 0;       /* shouldn't happen, but avoids warnings */
    }
  }
  return 0;
}

void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel) {
  if (y >= 0 && x >= 0 && x <= surface->w && y <= surface->h) {
    int bpp = surface->format->BytesPerPixel;
    /* Here p is the address to the pixel we want to set */
    Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;

    switch(bpp) {
    case 1:
        *p = pixel;
        break;

    case 2:
        *(Uint16 *)p = pixel;
        break;

    case 3:
        if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
            p[0] = (pixel >> 16) & 0xff;
            p[1] = (pixel >> 8) & 0xff;
            p[2] = pixel & 0xff;
        } else {
            p[0] = pixel & 0xff;
            p[1] = (pixel >> 8) & 0xff;
            p[2] = (pixel >> 16) & 0xff;
        }
        break;

    case 4:
        *(Uint32 *)p = pixel;
        break;
    }
  }
}