source: trunk/vizservers/nanovis/imgLoaders/BMPImageLoaderImpl.cpp @ 823

#include "BMPImageLoaderImpl.h"
#include "Image.h"
#include <stdio.h>
#include <memory.h>
#include <stdlib.h>

BMPImageLoaderImpl::BMPImageLoaderImpl()
{
}

BMPImageLoaderImpl::~BMPImageLoaderImpl()
{
}

// I referred to cjbackhouse@hotmail.com                www.backhouse.tk
Image* BMPImageLoaderImpl::load(const char* fileName)
{
    printf("BMP loader\n");
    fflush(stdout);
    Image* image = 0;

    FILE* f = fopen(fileName, "rb");

    if (!f)  {
        printf("File not found\n");
        return 0;
    }

    char header[54];
    fread(&header, 54, 1, f);

    if (header[0] != 'B' ||  header[1] != 'M')
    {
        printf("File is not BMP format\n");
        return 0;
    }

        //it seems gimp sometimes makes its headers small, so we have to do this. hence all the fseeks
        int offset=*(unsigned int*)(header+10);
        
        const unsigned int width =*(int*) (header+18);
        const unsigned int height =*(int*) (header+22);

        int bits=int(header[28]);               //colourdepth

    printf("image width = %d height = %d bits=%d\n", width, height, bits);
    fflush(stdout);
    
    image = new Image(width, height, _targetImageFormat, Image::IMG_UNSIGNED_BYTE, 0);

    printf("image created\n");
    fflush(stdout);

    unsigned char* bytes = (unsigned char*) image->getImageBuffer();
    memset(bytes, 0, sizeof(unsigned char) * width * height * _targetImageFormat);

    printf("reset image buffer\n");
    fflush(stdout);

        int x,y,c;
        unsigned char cols[256*4];                              //colourtable
        switch(bits)
        {
        case(24):
                fseek(f,offset,SEEK_SET);
        if (_targetImageFormat == Image::IMG_RGB)
        {
                    fread(bytes,width*height*3,1,f);    //24bit is easy
                    for(x=0;x<width*height*3;x+=3)                      //except the format is BGR, grr
                    {
                            unsigned char temp = bytes[x];
                            bytes[x] = bytes[x+2];
                            bytes[x+2] = temp;
                    }
        }
        else if (_targetImageFormat == Image::IMG_RGBA)
        {
            char* buff = (char*) malloc(width * height * sizeof(unsigned char) * 3);
                    fread(buff,width*height*3,1,f);                     //24bit is easy
                    for(x=0, y = 0;x<width*height*3;x+=3, y+=4)         //except the format is BGR, grr
                    {
                            bytes[y] = buff[x+2];
                            bytes[y+2] = buff[x];
                bytes[y+3] = 255;
                    }
            free(buff);
        }
                break;
        case(8):
                fread(cols,256 * 4,1,f);                                                        //read colortable
                fseek(f,offset,SEEK_SET);
                for(y=0;y<height;++y)                                           //(Notice 4bytes/col for some reason)
        {
                        for(x=0;x<width;++x)
                        {
                                unsigned char byte;                     
                                fread(&byte,1,1,f);                                                     //just read byte                                        
                                for(int c=0; c< 3; ++c)
                {
                    //bytes[(y*width+x)*3+c] = cols[byte*4+2-c];        //and look up in the table 
                    bytes[(y*width+x)*_targetImageFormat + c] = cols[byte*4+2-c];       //and look up in the table 
                }
            } 
        }
            break;
    /*
        case(4):
                fread(cols,16*4,1,f);
                fseek(f,offset,SEEK_SET);
                for(y=0;y<256;++y)
                        for(x=0;x<256;x+=2)
                        {
                                BYTE byte;
                                fread(&byte,1,1,f);                                             //as above, but need to exract two

                                for(c=0;c<_targetImageFormat;++c)                                               //pixels from each byte
                                        bmp.pixel(x,y,c)=cols[byte/16*4+2-c];

                                for(c=0;c<_targetImageFormat;++c)
                                        bmp.pixel(x+1,y,c)=cols[byte%16*4+2-c];
    */
    }

    printf("image initialized\n");
    fflush(stdout);
    return image;
}