#ifdef G_OS_WIN32
  #define WIN32_LEAN_AND_MEAN 1
  #include <windows.h>
  #define GL_BGR  0x80E0
  #define GL_BGRA 0x80E1
  #define GL_CLAMP_TO_EDGE 0x812F
#endif

#include <GL/gl.h>
#include <GL/glu.h>
#include <stdio.h>
#include <stdlib.h>

#include "bitmap.h"

#define BITMAP_FILESIZE 0x02
#define BITMAP_OFFSET 0x0a
#define BITMAP_HEADERSIZE 0x0e
#define BITMAP_WIDTH 0x12
#define BITMAP_HEIGHT 0x16
#define BITMAP_DEPTH 0x1c
#define BITMAP_IMAGE_SIZE 0x22


struct BitmapStruct BitmapLoad(char *filename)
{
  struct BitmapStruct l_sImage;
  GLuint texture;
  FILE *bitmap;

  // try to open the file
  bitmap = fopen(filename, "r");

  // does the bitmap exist?
  if (bitmap > 0)
  {
    unsigned int dataoffset, filesize, imagesize;
    short depth;
    GLsizei width, height;
    unsigned char *imagedata;

    fseek(bitmap, BITMAP_FILESIZE, SEEK_SET);
    fread(&filesize, 4, 1, bitmap);
    fseek(bitmap, BITMAP_OFFSET, SEEK_SET);
    fread(&dataoffset, 4, 1, bitmap);
    fseek(bitmap, BITMAP_WIDTH, SEEK_SET);
    fread(&width, 4, 1, bitmap);
    fread(&height, 4, 1, bitmap);
    fseek(bitmap, BITMAP_DEPTH, SEEK_SET);
    fread(&depth, 2, 1, bitmap);
    fseek(bitmap, BITMAP_IMAGE_SIZE, SEEK_SET);
    fread(&imagesize, 4, 1, bitmap);

    imagedata = (unsigned char *)malloc((size_t)imagesize);

    fseek(bitmap, dataoffset, SEEK_SET);
    fread(imagedata, (size_t)imagesize, 1, bitmap);

    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);

    if (depth == 24) // 24 bits
    {
      gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, width, height, GL_BGR, GL_UNSIGNED_BYTE, imagedata);
    }
    else // depth == 32 bits
    {
      gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, width, height, GL_BGRA, GL_UNSIGNED_BYTE, imagedata);;
    }

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
	  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    l_sImage.m_iImageId = texture;
    l_sImage.m_iWidth   = width;
    l_sImage.m_iHeight  = height;

    free(imagedata);
    fclose(bitmap);

    return l_sImage;
  }
  else
  {
    // couldn't find bitmap
    exit(0);
  }
}


void BitmapRender(int f_iXPos, int f_iYPos, int f_iWidth, int f_iHeight, int f_iImageId)
{
  glBindTexture(GL_TEXTURE_2D, f_iImageId);

  glBegin(GL_TRIANGLE_STRIP);
    glTexCoord2i(0, 1); glVertex2i(f_iXPos,            f_iYPos);
    glTexCoord2i(1, 1); glVertex2i(f_iXPos + f_iWidth, f_iYPos);
    glTexCoord2i(0, 0); glVertex2i(f_iXPos,            f_iYPos + f_iHeight);
    glTexCoord2i(1, 0); glVertex2i(f_iXPos + f_iWidth, f_iYPos + f_iHeight);
  glEnd();

} // BitmapRender


void BitmapConvertWidth(struct BitmapStruct *f_sImage, double f_dHeight)
{
  double l_dRatio;

  l_dRatio = (double)f_sImage->m_iHeight / f_dHeight;
  f_sImage->m_iWidth = (int)(f_sImage->m_iWidth / l_dRatio);

} // ConvertButton