bmp reader

bmp_read.cpp

#include <iostream>
#include <fstream>

#include "main.h"

int main(int argc, char *argv[])
{
	if (argc < 2) {
		std::cout << "Usage: " << argv[0] << " file_name" << std::endl;
		return 0;
	}

	char *fileName = argv[1];

	// открываем файл
	std::ifstream fileStream(fileName, std::ifstream::binary);
	if (!fileStream) {
		std::cout << "Error opening file '" << fileName << "'." << std::endl;
		return 0;
	}

	// заголовк изображения
	BITMAPFILEHEADER fileHeader;
	read(fileStream, fileHeader.bfType, sizeof(fileHeader.bfType));
	read(fileStream, fileHeader.bfSize, sizeof(fileHeader.bfSize));
	read(fileStream, fileHeader.bfReserved1, sizeof(fileHeader.bfReserved1));
	read(fileStream, fileHeader.bfReserved2, sizeof(fileHeader.bfReserved2));
	read(fileStream, fileHeader.bfOffBits, sizeof(fileHeader.bfOffBits));

	if (fileHeader.bfType != 0x4D42) {
		std::cout << "Error: '" << fileName << "' is not BMP file." << std::endl;
		return 0;
	}

	// информация изображения
	BITMAPINFOHEADER fileInfoHeader;
	read(fileStream, fileInfoHeader.biSize, sizeof(fileInfoHeader.biSize));

	// bmp core
	if (fileInfoHeader.biSize >= 12) {
		read(fileStream, fileInfoHeader.biWidth, sizeof(fileInfoHeader.biWidth));
		read(fileStream, fileInfoHeader.biHeight, sizeof(fileInfoHeader.biHeight));
		read(fileStream, fileInfoHeader.biPlanes, sizeof(fileInfoHeader.biPlanes));
		read(fileStream, fileInfoHeader.biBitCount, sizeof(fileInfoHeader.biBitCount));
	}

	// получаем информацию о битности
	int colorsCount = fileInfoHeader.biBitCount >> 3;
	if (colorsCount < 3) {
		colorsCount = 3;
	}

	int bitsOnColor = fileInfoHeader.biBitCount / colorsCount;
	int maskValue = (1 << bitsOnColor) - 1;

	// bmp v1
	if (fileInfoHeader.biSize >= 40) {
		read(fileStream, fileInfoHeader.biCompression, sizeof(fileInfoHeader.biCompression));
		read(fileStream, fileInfoHeader.biSizeImage, sizeof(fileInfoHeader.biSizeImage));
		read(fileStream, fileInfoHeader.biXPelsPerMeter, sizeof(fileInfoHeader.biXPelsPerMeter));
		read(fileStream, fileInfoHeader.biYPelsPerMeter, sizeof(fileInfoHeader.biYPelsPerMeter));
		read(fileStream, fileInfoHeader.biClrUsed, sizeof(fileInfoHeader.biClrUsed));
		read(fileStream, fileInfoHeader.biClrImportant, sizeof(fileInfoHeader.biClrImportant));
	}

	// bmp v2
	fileInfoHeader.biRedMask = 0;
	fileInfoHeader.biGreenMask = 0;
	fileInfoHeader.biBlueMask = 0;

	if (fileInfoHeader.biSize >= 52) {
		read(fileStream, fileInfoHeader.biRedMask, sizeof(fileInfoHeader.biRedMask));
		read(fileStream, fileInfoHeader.biGreenMask, sizeof(fileInfoHeader.biGreenMask));
		read(fileStream, fileInfoHeader.biBlueMask, sizeof(fileInfoHeader.biBlueMask));
	}

	// если маска не задана, то ставим маску по умолчанию
	if (fileInfoHeader.biRedMask == 0 || fileInfoHeader.biGreenMask == 0 || fileInfoHeader.biBlueMask == 0) {
		fileInfoHeader.biRedMask = maskValue << (bitsOnColor * 2);
		fileInfoHeader.biGreenMask = maskValue << bitsOnColor;
		fileInfoHeader.biBlueMask = maskValue;
	}

	// bmp v3
	if (fileInfoHeader.biSize >= 56) {
		read(fileStream, fileInfoHeader.biAlphaMask, sizeof(fileInfoHeader.biAlphaMask));
	} else {
		fileInfoHeader.biAlphaMask = maskValue << (bitsOnColor * 3);
	}

	// bmp v4
	if (fileInfoHeader.biSize >= 108) {
		read(fileStream, fileInfoHeader.biCSType, sizeof(fileInfoHeader.biCSType));
		read(fileStream, fileInfoHeader.biEndpoints, sizeof(fileInfoHeader.biEndpoints));
		read(fileStream, fileInfoHeader.biGammaRed, sizeof(fileInfoHeader.biGammaRed));
		read(fileStream, fileInfoHeader.biGammaGreen, sizeof(fileInfoHeader.biGammaGreen));
		read(fileStream, fileInfoHeader.biGammaBlue, sizeof(fileInfoHeader.biGammaBlue));
	}

	// bmp v5
	if (fileInfoHeader.biSize >= 124) {
		read(fileStream, fileInfoHeader.biIntent, sizeof(fileInfoHeader.biIntent));
		read(fileStream, fileInfoHeader.biProfileData, sizeof(fileInfoHeader.biProfileData));
		read(fileStream, fileInfoHeader.biProfileSize, sizeof(fileInfoHeader.biProfileSize));
		read(fileStream, fileInfoHeader.biReserved, sizeof(fileInfoHeader.biReserved));
	}

	// проверка на поддерку этой версии формата
	if (fileInfoHeader.biSize != 12 && fileInfoHeader.biSize != 40 && fileInfoHeader.biSize != 52 &&
	    fileInfoHeader.biSize != 56 && fileInfoHeader.biSize != 108 && fileInfoHeader.biSize != 124) {
		std::cout << "Error: Unsupported BMP format." << std::endl;
		return 0;
	}

	if (fileInfoHeader.biBitCount != 16 && fileInfoHeader.biBitCount != 24 && fileInfoHeader.biBitCount != 32) {
		std::cout << "Error: Unsupported BMP bit count." << std::endl;
		return 0;
	}

	if (fileInfoHeader.biCompression != 0 && fileInfoHeader.biCompression != 3) {
		std::cout << "Error: Unsupported BMP compression." << std::endl;
		return 0;
	}

	// rgb info
	RGBQUAD **rgbInfo = new RGBQUAD*[fileInfoHeader.biHeight];
	
	for (unsigned int i = 0; i < fileInfoHeader.biHeight; i++) {
		rgbInfo[i] = new RGBQUAD[fileInfoHeader.biWidth];
	}

	// определение размера отступа в конце каждой строки
	int linePadding = ((fileInfoHeader.biWidth * (fileInfoHeader.biBitCount / 8)) % 4) & 3;

	// чтение
	unsigned int bufer;

	for (unsigned int i = 0; i < fileInfoHeader.biHeight; i++) {
		for (unsigned int j = 0; j < fileInfoHeader.biWidth; j++) {
			read(fileStream, bufer, fileInfoHeader.biBitCount / 8);

			rgbInfo[i][j].rgbRed = bitextract(bufer, fileInfoHeader.biRedMask);
			rgbInfo[i][j].rgbGreen = bitextract(bufer, fileInfoHeader.biGreenMask);
			rgbInfo[i][j].rgbBlue = bitextract(bufer, fileInfoHeader.biBlueMask);
			rgbInfo[i][j].rgbReserved = bitextract(bufer, fileInfoHeader.biAlphaMask);
		}
		fileStream.seekg(linePadding, std::ios_base::cur);
	}

	// вывод
	for (unsigned int i = 0; i < fileInfoHeader.biHeight; i++) {
		for (unsigned int j = 0; j < fileInfoHeader.biWidth; j++) {
			std::cout << std::hex
			          << +rgbInfo[i][j].rgbRed << " "
			          << +rgbInfo[i][j].rgbGreen << " "
			          << +rgbInfo[i][j].rgbBlue << " "
			          << +rgbInfo[i][j].rgbReserved
			          << std::endl;
		}
		std::cout << std::endl;
	}

	return 1;
}

unsigned char bitextract(const unsigned int byte, const unsigned int mask) {
	if (mask == 0) {
		return 0;
	}

	// определение количества нулевых бит справа от маски
	int
		maskBufer = mask,
		maskPadding = 0;

	while (!(maskBufer & 1)) {
		maskBufer >>= 1;
		maskPadding++;
	}

	// применение маски и смещение
	return (byte & mask) >> maskPadding;
}

bmp_read.h

#ifndef MAIN_H_INCLUDED
#define MAIN_H_INCLUDED

// CIEXYZTRIPLE stuff
typedef int FXPT2DOT30;

typedef struct {
	FXPT2DOT30 ciexyzX;
	FXPT2DOT30 ciexyzY;
	FXPT2DOT30 ciexyzZ;
} CIEXYZ;

typedef struct {
	CIEXYZ  ciexyzRed; 
	CIEXYZ  ciexyzGreen; 
	CIEXYZ  ciexyzBlue; 
} CIEXYZTRIPLE;

// bitmap file header
typedef struct {
	unsigned short bfType;
	unsigned int   bfSize;
	unsigned short bfReserved1;
	unsigned short bfReserved2;
	unsigned int   bfOffBits;
} BITMAPFILEHEADER;

// bitmap info header
typedef struct {
	unsigned int   biSize;
	unsigned int   biWidth;
	unsigned int   biHeight;
	unsigned short biPlanes;
	unsigned short biBitCount;
	unsigned int   biCompression;
	unsigned int   biSizeImage;
	unsigned int   biXPelsPerMeter;
	unsigned int   biYPelsPerMeter;
	unsigned int   biClrUsed;
	unsigned int   biClrImportant;
	unsigned int   biRedMask;
	unsigned int   biGreenMask;
	unsigned int   biBlueMask;
	unsigned int   biAlphaMask;
	unsigned int   biCSType;
	CIEXYZTRIPLE   biEndpoints;
	unsigned int   biGammaRed;
	unsigned int   biGammaGreen;
	unsigned int   biGammaBlue;
	unsigned int   biIntent;
	unsigned int   biProfileData;
	unsigned int   biProfileSize;
	unsigned int   biReserved;
} BITMAPINFOHEADER;

// rgb quad
typedef struct {
	unsigned char  rgbBlue;
	unsigned char  rgbGreen;
	unsigned char  rgbRed;
	unsigned char  rgbReserved;
} RGBQUAD;

// read bytes
template <typename Type>
void read(std::ifstream &fp, Type &result, std::size_t size) {
	fp.read(reinterpret_cast<char*>(&result), size);
}

// bit extract
unsigned char bitextract(const unsigned int byte, const unsigned int mask);

#endif // MAIN_H_INCLUDEDs

	fileStream.seekg(linePadding, std::ios_base::cur);

Забавно. Что будешь делать если картинка без паддинга?
malloc/new нужного тебе размера (linePadding * height).

Если картинка без паддинга то linePadding == 0 . Но там и без этого вариант такой себе.