bmpLoader by MaFiaBoY

1

#include "BMPLoader.h" BMPClass::BMPClass(){bytes=0;} BMPClass::~BMPClass(){delete[] bytes;} BYTE& BMPClass::pixel(int x,int y,int c){return bytes[(y*width+x)*3+c];} void BMPClass::allocateMem(){delete[] bytes;bytes=new BYTE[width*height*3];} std::string TranslateBMPError(BMPError err) {     switch(err)     {     case(BMPNOTABITMAP):         return "This file is not a bitmap, specifically it doesn't start 'BM'";     case(BMPNOOPEN):         return "Failed to open the file, suspect it doesn't exist";     case(BMPFILEERROR):         return "Some kind of error while physically reading the file";     case(BMPNOERROR):         return "No errors detected";     case(BMPUNKNOWNFORMAT):         return "Unknown bmp format, ie not 24bit, 256,16 or 2 colour";     default:         return "Not a valid error code";     } } BMPError BMPLoad(std::string fname,BMPClass& bmp) {     FILE * f=fopen(fname.c_str(),"rb");        //open for reading in binary mode     if(!f) return BMPNOOPEN;     char header[54];     fread(header,54,1,f);            //read the 54bit main header     if(header[0]!='B' || header[1]!='M')     {         fclose(f);         return BMPNOTABITMAP;        //all bitmaps should start "BM"     }     if(sizeof(int)==4)    //Annoyingly I can't just assume this     {         bmp.width=*(int*)(header+18);         bmp.height=*(int*)(header+22);     }     else     {         bmp.width=header[18]+256*header[19]+256*256*header[20]+256*256*256*header[21];         bmp.height=header[22]+256*header[23]+256*256*header[24]+256*256*256*header[25];     }     bmp.allocateMem();     int bits=int(header[28]);        //colourdepth     int x,y,c;     BYTE cols[256*4];     switch(bits)     {     case(24):         fread(bmp.bytes,bmp.width*bmp.height*3,1,f);    //24bit is easy         for(x=0;x<bmp.width*bmp.height*3;x+=3)            //except the format is BGR, grr         {             BYTE temp=bmp.bytes[x];             bmp.bytes[x]=bmp.bytes[x+2];             bmp.bytes[x+2]=temp;         }         break;     case(8):         fread(cols,256*4,1,f);                            //read colortable         for(y=0;y<bmp.height;++y)                        //(Notice 4bytes/col for some reason)             for(x=0;x<bmp.width;++x)             {                 BYTE byte;                             fread(&byte,1,1,f);                        //just read byte                                     for(int c=0;c<3;++c)                     bmp.pixel(x,y,c)=cols[byte*4+2-c];    //and look up in the table             }         break;     case(4):         fread(cols,16*4,1,f);         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<3;++c)                        //pixels from each byte                     bmp.pixel(x,y,c)=cols[byte/16*4+2-c];                 for(c=0;c<3;++c)                     bmp.pixel(x+1,y,c)=cols[byte%16*4+2-c];             }         break;     //NOT CURRENTLY WORKING PROPERLY     case(1):         fread(cols,8,1,f);        //colourtable         for(y=0;y<256;++y)             for(x=0;x<256;x+=8)             {                 BYTE byte;                 fread(&byte,1,1,f);                 //The idea here is that every byte is eight pixels                 //so I'm shifting the byte to the relevant position, then masking out                 //all but the lowest bit in order to get the index into the colourtable.                 for(int x2=0;x2<8;++x2)                 {                     for(int c=0;c<3;++c)                         bmp.pixel(x+x2,y,c)=cols[((byte>>(7-x2))&1)*4+2-c];                 }             }         break;     default:         fclose(f);         return BMPUNKNOWNFORMAT;     }     fclose(f);     if(ferror(f)) return BMPFILEERROR;     return BMPNOERROR; } BMPError BMPLoad(std::string fname){BMPClass bmp;return BMPLoad(fname,bmp);} #ifdef __gl_h BMPError BMPLoadGL(std::string fname) {     BMPClass bmp;     BMPError e=BMPLoad(fname,bmp);     if(e!=BMPNOERROR) return e;              glEnable(GL_TEXTURE_2D);     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);     glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);     glTexImage2D(GL_TEXTURE_2D,0,3,bmp.width,bmp.height,0,GL_RGB,GL_UNSIGNED_BYTE,bmp.bytes);     return BMPNOERROR; } #endif