bitmapOps.cpp

#include <stdio.h> 
#include <windows.h>
#include <vector>

typedef struct COLOR {
	BYTE    rgbaBlue;
	BYTE    rgbaGreen;
	BYTE    rgbaRed;
	BYTE    rgbaAlpha;
} *PCOLOR;

class Bitmap {
public:
	PBITMAPFILEHEADER fileHeader;
	PBITMAPINFOHEADER infoHeader;

	Bitmap(const char*);
	// Contains padding as well
	std::vector<uint8_t> read_bmpImageData();
	std::vector<uint8_t> image_black();
	std::vector<uint8_t> image_shift(int, int);

	static void write(int, int, std::vector<uint8_t>);
private:
	FILE* fp;
	const char* path;
};

int main(void)
{
	Bitmap* b = new Bitmap("D:\\1.bmp");
	std::vector<uint8_t> imageData = b->read_bmpImageData();
	b->write(b->infoHeader->biWidth, b->infoHeader->biHeight, b->image_shift(-50, 70));
	return 0;
}

Bitmap::Bitmap(const char* path) {
	errno_t err;
	if ((err = fopen_s(&fp, path, "rb")) != NULL)
	{
		throw "can't open the bmp imgae.";
	}
	this->path = path;

	fileHeader = new BITMAPFILEHEADER;
	fread(fileHeader, sizeof(BITMAPFILEHEADER), 1, fp);
	infoHeader = new BITMAPINFOHEADER;
	fread(infoHeader, sizeof(BITMAPINFOHEADER), 1, fp);
	
	if (infoHeader->biSize != 40) {
		throw "bit marks not supported";
	}
	if (infoHeader->biBitCount != 8) {
		throw "8 bit(grey scale) images only";
	}
	if (infoHeader->biCompression != 0) {
		throw "compression not supported";
	}

	printf("类型为\t%c%c\n", (char)fileHeader->bfType, (char)(fileHeader->bfType >> 8));
	printf("大小\t%d\n", fileHeader->bfSize);
	printf("高度\t%d\n", infoHeader->biHeight);
	printf("宽度\t%d\n", infoHeader->biWidth);
}

std::vector<uint8_t> Bitmap::read_bmpImageData() {
	if (fseek(fp, fileHeader->bfOffBits, SEEK_SET) != 0) {
		throw "cannot locate color bits";
	}

	std::vector<uint8_t> data;
	data.resize(infoHeader->biWidth * infoHeader->biHeight);
	fread(data.data(), data.size(), 1, fp);
	return data;
}

std::vector<uint8_t> Bitmap::image_black() {
	std::vector<uint8_t> image = read_bmpImageData();
	int width = infoHeader->biWidth;
	int height = infoHeader->biHeight;
	for (int i = 0; i < 50; i++) {
		for (int j = 0; j < 50; j++) {
			image[i * width + j] = 1;
			image[(height - i - 1) * width + j] = 1;
			image[i * width + (width - j - 1)] = 1;
			image[(height - i - 1) * width + (width - j - 1)] = 1;
		}
	}
	return image;
}

std::vector<uint8_t> Bitmap::image_shift(int l2r, int t2b) {
	int width = infoHeader->biWidth;
	int height = infoHeader->biHeight;

	std::vector<uint8_t> original = read_bmpImageData();
	std::vector<uint8_t> image = read_bmpImageData();
	image.resize(height * width);

	// i is row while j is column
	if (l2r != 0) {
		for (int i = 0; i < height; i++) {
			for (int j = 0; j < width; j++) {
				if ((l2r < 0 && j >= width + l2r) || (l2r > 0 && j <= l2r)) {
					image[i * width + j] = 0;
					continue;
				}
				image[i * width + j] = original[i * width + j - l2r];
			}
		}
	}

	original = image;
	if (t2b != 0) {
		for (int i = 0; i < height; i++) {
			for (int j = 0; j < width; j++) {
				if ((t2b > 0 && i >= height - t2b) || (t2b < 0 && i <= -t2b)) {
					image[i * width + j] = 0;
					continue;
				}
				image[i * width + j] = original[(i + t2b) * width + j];
			}
		}
	}
	return image;
}

void Bitmap::write(int width, int height, std::vector<uint8_t> data) {
	if (data.size() != width * height) {
		throw "size not equal";
	}
	errno_t err;
	FILE* fp;
	if ((err = fopen_s(&fp, "D:\\rewriten.bmp", "wb")) != NULL)
	{
		throw "can't open the bmp imgae.";
	}

	BITMAPFILEHEADER fh = {};
	BITMAPINFOHEADER ih = {};

	std::vector<COLOR> colors = {};
	for (uint8_t i = 0; i < (2 << 7) - 1; i++) {
		colors.push_back(COLOR{i,i,i,0});
	}
	colors.push_back(COLOR{ 0xff,0xff,0xff,0 });
	COLOR* colorTable = colors.data();

	fh.bfType = 0x4d42;
	fh.bfSize = sizeof(fh) + sizeof(ih) + data.size() + (2 << 7) * sizeof(DWORD);
	fh.bfOffBits = sizeof(fh) + sizeof(ih) + (2 << 7) * sizeof(DWORD);
	ih.biSize = sizeof(ih);
	ih.biWidth = width;
	ih.biHeight = height;
	ih.biBitCount = 8;
	ih.biCompression = 0;
	ih.biPlanes = 1;
	ih.biSizeImage = data.size();
	ih.biClrUsed = 2 << 7;
	ih.biClrImportant = 2 << 7;
	fwrite(&fh, sizeof(fh), 1, fp);
	fwrite(&ih, sizeof(ih), 1, fp);
	fwrite(colorTable, (2 << 7) * sizeof(COLOR), 1, fp);
	fwrite(data.data(), data.size(), 1, fp);

	ShellExecute(NULL, NULL, L"D:\\rewriten.bmp", NULL, NULL, SW_SHOW);
}