/Users/craigcornelius/Projects/SPRING Mac Release 0.2/imagebmp.h

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//
// ImageBMP - class for reading in a Windows BMP file
//

#ifndef ImageBMP_Header
#define ImageBMP_Header

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

typedef unsigned long ulong;
typedef unsigned short ushort;
typedef unsigned char uchar;

class ImageBMP {
public:
    // header
    char sig[2];
    ulong filesize;
    ulong reserved;
    ulong dataoffset;
    
    // info header
    ulong infoheadersize;
    ulong width;
    ulong height;
    ushort depth;
    ushort bitsperpixel;
    ulong compression; // 0=none, 1=8bit RLE, 2=4bit RLE
    ulong imagesize;    // 0=no compression
    ulong xpixperm;     // xpixels per meter
    ulong ypixperm;     // ypixels per meter
    ulong colorsused;  // actually used colors
    ulong colorsimportant; // num important colors (0=all)
    
    // color table (4 * numcolors if bitsperpixel<=8)
    struct colorentry { uchar r,g,b,a; };
    colorentry* colortable;  //  numcolors entries
    
    // pixeldata: 
    //  bottom up, left-to-right, RGBA
    //  lines padded to fill 4-byte word
    uchar* imagedata;
    
    // functions
    uchar get_uchar(FILE* fp);
    ushort get_ushort(FILE* fp);
    ulong  get_ulong(FILE* fp);
    
    // public functions
    ImageBMP();
    ~ImageBMP();
    int Read(char* filename);
};

inline ImageBMP::ImageBMP() 
{ filesize = reserved = dataoffset = width = height = 0; 
colortable = NULL; imagedata = NULL; }

inline ImageBMP::~ImageBMP()
{ 
    if (colortable) { delete colortable; colortable = NULL; }
    if (imagedata) { delete imagedata; imagedata = NULL; }
}

inline uchar ImageBMP::get_uchar(FILE* fp)
{
    uchar val;
    fread(&val, 1, sizeof(uchar), fp);
    return(val);
}

inline ushort ImageBMP::get_ushort(FILE* fp)
{
    ushort val;
    fread(&val, 1, sizeof(ushort), fp);
#ifdef _WIN32
    return(val);
#else
    // swab bytes (little endian-big endian thing)
    return( ((val & 0x00ff) << 8) | ((val & 0xff00) >> 8) );
#endif
}

inline ulong ImageBMP::get_ulong(FILE* fp)
{
    ushort val1 = get_ushort(fp); 
    ushort val2 = get_ushort(fp);
    ulong val = (val2 << 16) | val1;
    return( val );
}

inline int ImageBMP::Read(char* filename) 
{
        using namespace std;

    // if there's already old data, get rid of it
    if (colortable) { delete colortable; colortable = NULL; }
    if (imagedata) { delete imagedata; imagedata = NULL; }
    
    // open the given file
    FILE* fp = fopen(filename, "rb");
    if (!fp) { cerr << "can't open [" << filename << "]\n"; return(-1); }
    
    // header
    sig[0] = get_uchar(fp);
    sig[1] = get_uchar(fp);
    filesize = get_ulong(fp);   // filesize
    reserved = get_ulong(fp);   // reserved
    dataoffset = get_ulong(fp); // dataoffset
    
    // sanity check
    if ((sig[0] != 'B') || (sig[1] != 'M')) { 
        cerr << "not a BMP file\n"; 
        fclose(fp);
        return(-1); }
    
    // info header
    infoheadersize = get_ulong(fp);
    width = get_ulong(fp);
    height = get_ulong(fp);
    depth = get_ushort(fp);
    bitsperpixel = get_ushort(fp);
    compression = get_ulong(fp);
    imagesize = get_ulong(fp);
    xpixperm = get_ulong(fp);
    ypixperm = get_ulong(fp);
    colorsused = get_ulong(fp);
    colorsimportant = get_ulong(fp);
    
    // sanity checks
    if (compression != 0) { 
        cerr << "can't do compression=" << compression << endl; 
        fclose(fp);
        return(-1); 
    }
    if (bitsperpixel != 24) {
        cerr << "can't do bitsperpixel=" << bitsperpixel << endl; 
        fclose(fp);
        return(-1); 
    }
    
    // debugging
    cerr << "sig= " << sig 
        << ", compression = " << compression
        << ", depth = " << depth
        << ", bitsperpixel = " << bitsperpixel
        << "\n width = " << width << ", height = " << height 
        << endl;
    
    // read in the colortable
    // there is none for compression=0, bitsperpixel=24!
    colortable = NULL;
    
    // read in the pixels
    imagedata = new uchar[width * height * 4];
    for (ushort y=0; y<height; y++) {
        for (ushort x=0; x<width; x++) {
            uchar r,g,b;
            r = get_uchar(fp); g = get_uchar(fp); b = get_uchar(fp); 
            imagedata[y*width*3 + x*3 + 0] = b;
            imagedata[y*width*3 + x*3 + 1] = g;
            imagedata[y*width*3 + x*3 + 2] = r;
            imagedata[y*width*3 + x*3 + 3] = 255;
        }
    }
    
    // finish up
    fclose(fp);
    return(0);  // success
}

#endif

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