【C/C++】BITMAP格式分析

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typedef struct tagBITMAPFILEHEADER {
        WORD    bfType;
        DWORD   bfSize;
        WORD    bfReserved1;
        WORD    bfReserved2;
        DWORD   bfOffBits;
} BITMAPFILEHEADER, FAR *LPBITMAPFILEHEADER, *PBITMAPFILEHEADER;

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typedef struct tagBITMAPINFOHEADER{
        DWORD      biSize;
        LONG       biWidth;
        LONG       biHeight;
        WORD       biPlanes;
        WORD       biBitCount;
        DWORD      biCompression;
        DWORD      biSizeImage;
        LONG       biXPelsPerMeter;
        LONG       biYPelsPerMeter;
        DWORD      biClrUsed;
        DWORD      biClrImportant;
} BITMAPINFOHEADER, FAR *LPBITMAPINFOHEADER, *PBITMAPINFOHEADER;

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typedef struct tagRGBQUAD {
        BYTE    rgbBlue;             //该颜色蓝色分量
        BYTE    rgbGreen;            //该绿色蓝色分量
        BYTE    rgbRed;              //该红色蓝色分量    
        BYTE    rgbReserved;         //保留
} RGBQUAD;

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

#pragma pack(push)
#pragma pack(1)

//24位真彩色
struct RGB
{
    BYTE			b;
    BYTE			g;
    BYTE			r;
};

#pragma pack(pop)

void imgOpr(RGB &a, RGB &b)
{
    b.b = a.b;
    b.g = a.g;
    b.r = a.r;
}

//二维数组申请img[m][n]
RGB ** RGB_new(int m, int n)
{
	int					i;
	RGB					**img;

	img = new RGB * [m];

	for (i = 0; i < m; i ++)
	{
		img[i] = new RGB [n];
	}

	return img;
}

//释放img[m][n]
void RGB_delete(RGB **img, int m, int n)
{
	int					i;

	for (i = 0; i < m; i ++)
	{
		delete [] img[i];
	}
 
	delete [] img;
}

int main()
{
    BITMAPFILEHEADER	bfh;
    BITMAPINFOHEADER	bih;

	RGB					**img1;
    RGB					**img2;
	BYTE				*tmp;

	int					i, j;
    int					height, width;
	int					m, n;

    FILE				*fp, *fq; 
	errno_t				err;
	
	err = fopen_s(&fp, "D:\Work\Debug\7.bmp", "rb");

	if (err == 0)
	{
		printf("The input file was opened!n");
	}
	else
	{
		printf("The input file was not opened!n");
		return 1;
	}

	err = fopen_s(&fq, "D:\Work\Debug\2.bmp", "wb");

	if (err == 0)
	{
		printf("The output file was opened!n");
	}
	else
	{
		printf("The output file was not opened!n");
		return 1;
	}

    fread(&bfh, sizeof(BITMAPFILEHEADER), 1, fp);
    fread(&bih, sizeof(BITMAPINFOHEADER), 1, fp);
    
	height = bih.biHeight;
    width = bih.biWidth;
	
	img1 = RGB_new(height, width);
	img2 = RGB_new(width, height);
	
	//计算每行图像字节数，必须是4的整倍数，不够需要填充
	m = (bih.biWidth * bih.biBitCount + 31) / 32 * 4; 
	n = (bih.biHeight * bih.biBitCount + 31) / 32 * 4;
	
	tmp = new BYTE [n];
	memset(tmp, 0x0, n);

    //对图片进行操作
	for (i = 0; i < height; i ++)
	{
		//跳过调色板数据段，并寻址
		fseek(fp, bfh.bfOffBits + i * m, SEEK_SET);
		fread(img1[i], sizeof(RGB), width, fp);

		for (j = 0; j < width; j ++)
		{
			//将数组 img 赋值给 img2
			imgOpr(img1[i][j], img2[j][i]);
		}
	}

	//更新BITMAPINFOHEADER结构体
	bih.biHeight = width;
	bih.biWidth = height;
	bih.biSizeImage = n * width;

	//将修改后的图片保存到文件
	fwrite(&bfh, sizeof(BITMAPFILEHEADER), 1, fq);
	fwrite(&bih, sizeof(BITMAPINFOHEADER), 1, fq);

	for (i = 0; i < width; i ++)
	{
		memcpy(tmp, img2[i], sizeof(RGB) * height);
		fwrite(tmp, 1, n, fq);
	}

    fclose(fp);
    fclose(fq);

	//释放
	RGB_delete(img1, height, width);
	RGB_delete(img2, width, height);
	
	delete [] tmp;
 
	system("pause");

    return 0;
}