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

#ifdef _WIN32
#   pragma warning( disable : 4996 ) // disable deprecated warning 
#endif

#pragma pack(1)

typedef struct{
    short type;
    int size;
    short reserved1;
    short reserved2;
    int offset;
} BMPHeader;

typedef struct{
    int size;
    int width;
    int height;
    short planes;
    short bitsPerPixel;
    unsigned compression;
    unsigned imageSize;
    int xPelsPerMeter;
    int yPelsPerMeter;
    int clrUsed;
    int clrImportant;
} BMPInfoHeader;



//Isolated definition
typedef struct{
    unsigned char x, y, z, w;
} uchar4;



extern "C" void LoadBMPFile(uchar4 **dst, int *width, int *height, const char *name){
    BMPHeader hdr;
    BMPInfoHeader infoHdr;
    int x, y;

    FILE *fd;


    //printf("導入圖片： %s...\n", name);
    if(sizeof(uchar4) != 4){
        printf("***Bad uchar4 size***\n");
        exit(0);
    }

    if( !(fd = fopen(name,"rb")) ){
        printf("***BMP load error: file access denied***\n");
        exit(0);
    }

    fread(&hdr, sizeof(hdr), 1, fd);
    if(hdr.type != 0x4D42){
        printf("***BMP load error: bad file format***\n");
        exit(0);
    }
    fread(&infoHdr, sizeof(infoHdr), 1, fd);

    if(infoHdr.bitsPerPixel != 24){
        printf("***BMP load error: invalid color depth***\n");
        exit(0);
    }

    if(infoHdr.compression){
        printf("***BMP load error: compressed image***\n");
        exit(0);
    }

    *width  = infoHdr.width;
    *height = infoHdr.height;
    *dst    = (uchar4 *)malloc(*width * *height * 4);

    //printf("BMP圖片寬度: %u\n", infoHdr.width);
   // printf("BMP圖片高度: %u\n", infoHdr.height);

    fseek(fd, hdr.offset - sizeof(hdr) - sizeof(infoHdr), SEEK_CUR);

    for(y = 0; y < infoHdr.height; y++){
        for(x = 0; x < infoHdr.width; x++){
            (*dst)[(y * infoHdr.width + x)].z = fgetc(fd);
            (*dst)[(y * infoHdr.width + x)].y = fgetc(fd);
            (*dst)[(y * infoHdr.width + x)].x = fgetc(fd);
        }

        for(x = 0; x < (4 - (3 * infoHdr.width) % 4) % 4; x++)
            fgetc(fd);
    }


    if(ferror(fd)){
        printf("***Unknown BMP load error.***\n");
        free(*dst);
        exit(0);
    }else
        printf("圖片導入成功！\n");

    fclose(fd);
}