Hi.

I've been trying to write a bitmap in C++, but so far the closest i've gotten is a blank bitmap file which says "drawing failed" when I open it. The code i've written below SHOULD make an entirely red bitmap, but no luck so far. Any ideas?

#include <iostream>
#include <fstream>

using namespace std; //keep this in or it breaks and dies horribly

struct BMFH { //declares BitMap File Header structure
unsigned short bfType; //might need to be a char
unsigned long bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned long bfOffBits;
};

struct BMIH { //declares BitMap Info Header structure
unsigned long biSize;
unsigned long biWidth;
unsigned long biHeight;
unsigned short biPlanes;
unsigned short biBitCount;
unsigned long biCompression;
unsigned long biSizeImage;
unsigned long biXPelsPerMeter;
unsigned long biYPelsPerMeter;
unsigned long biClrUsed;
unsigned long biClrImportant;
};

struct RGBQUAD{ //declares RGBQUAD
int rgbBlue;
int rgbGreen;
int rgbRed;
int rgbReserved;
};

struct pixel { //declares pixel structure

unsigned short R;
unsigned short G; //RGB values for each pixel
unsigned short B;
//unsigned short unused; //needed?
};

void setfileheader(BMFH& fileheader) //must pass by reference!
{ // Fills the file header with default values...

fileheader.bfType = 19778;
fileheader.bfSize = 108;
fileheader.bfReserved1 = 0;
fileheader.bfReserved2 = 0;
fileheader.bfOffBits = 1078;

}

void setinfoheader(BMIH& infoheader) //must pass by reference!
{ // Fills the file header with default values...

infoheader.biSize = sizeof(infoheader);
infoheader.biWidth = 128;
infoheader.biHeight = 128;
infoheader.biPlanes = 1;
infoheader.biBitCount = 24;
infoheader.biCompression = 0;
infoheader.biSizeImage = 0;
infoheader.biXPelsPerMeter = 0;
infoheader.biYPelsPerMeter = 0;
infoheader.biClrUsed = 0;
infoheader.biClrImportant = 0;

}

int main(){

//------------Setting up pixels and co-//

pixel PICTAR[128][128]; //declares an array of pixels

int i;
int j;

for (int i=0; i<128; i++){ //horizontal axis of pixels

for (int j=0; j<128; j++){ //vertical axis

PICTAR[i][j].R = 100; //make pixels red
PICTAR[i][j].G = 0;
PICTAR[i][j].B = 0;

}
}

-------------------//

ifstream::pos_type size; //special type used for file positioning; can treat as an integer
BMFH fileheader; //makes a header called "fileheader"
BMIH infoheader;

setfileheader(fileheader); //fills header with values
setinfoheader(infoheader);

ofstream myfile ("testbmp.bmp",ios::out | ios::binary); //creates an ofstream object called myfile
//and opens it for binary input

/////////////////////Writing////////////////////////////

//myfile.write ((char*) &fileheader,sizeof(fileheader)); //write header
//myfile.write ((char*) &infoheader,sizeof(infoheader)); //write header
myfile.write ((char*) &fileheader,14); //write header
myfile.write ((char*) &infoheader,40); //write header
myfile.write ((char*) &PICTAR,sizeof(pixel)*128*128);
myfile.close();

}

Thanks for your time,

Nil

2 points
1) pixels should be char not unsigned short
2) for some unknown to me reason the struct BMFH caused the long bfSize (file size) to be incorrect and to have hex &hCC overwriting the first 2 bytes

guest