c++实现bmp文件的读写

程序分为bmp相关的三个文件以及一个实例文件：

 1.bmp格式文件的结构体定义--  bmpstruct.h

 2.bmp格式文件的类定义文件-- cBMPimage.h

 3.bmp格式文件的类实现文件 - cBMPimage.cpp

  4示例文件--main.c

 

1.bmpstruct.h

#ifndef BMPSTRUCT#define BMPSTRUCT//~~~~~~~~~~~~~~~~~~结构体定义~~~~~~~~~~~~~~~~~~~~~~~~//typedef struct tagBMPHEADER{unsigned short bfType; //文件类型unsigned long bfSize; //bmp文件长度WORD Reserved1;WORD Reserved2;unsigned long bfOffset; //文件描述区长度，16色为118，256色为1078}BMPHEADER;//现在算一下，有3个int，2个long，正好3*2+2*4=14字节//图像信息区typedef struct  tagBMPINFOHEADER{DWORD biSize;LONG biWidth;LONG biHeight;WORD biPlanes;WORD biBitCount;DWORD biCompression;DWORD biSizeImage;LONG biXplosPerMeter;LONG biYplosPerMeter;DWORD biClrUsed;DWORD biClrImportant;} BMPINFOHEADER;// 2+2*9*4 =40 字节？有疑问//调色板typedef struct tagBMPRGBQUAD{BYTE rgbBlue;BYTE rgbGreen;BYTE rgbRed;BYTE rgbReserve;} BMPRGBQUAD;//位图数据typedef struct  tagIMAGEDATA{BYTE red;BYTE green;BYTE blue;}IMAGEDATA;#endif

2.cBMPimage.h

#pragma once#include <stdio.h>#include  <windows.h>#include "bmpstruct.h"class cBMPimage{public:BMPHEADER file;BMPINFOHEADER info;BMPRGBQUAD *palette;IMAGEDATA *imagedata;public:cBMPimage(void);~cBMPimage(void);public:int GetBmpSize(FILE *fp) ;int bmpload(const char* filename);int bmpsave(const char* filename);int bmpcopypara(cBMPimage *bmpimage);};

 

  3.cBMPimage.cpp  (实际使用时最好将printf去掉)

#include "cBMPimage.h"cBMPimage::cBMPimage(void){palette = NULL;imagedata = NULL;}cBMPimage::~cBMPimage(void){if (palette!=NULL){free(palette);palette = NULL;}if (imagedata!=NULL){free(imagedata);imagedata= NULL;}}int cBMPimage::GetBmpSize( FILE *fp ){long curpos;   // attention! this is a long type.   int len;  curpos = ftell(fp);  fseek(fp, 0, SEEK_END);  len = ftell(fp);  fseek(fp, curpos, SEEK_SET);   return len;  }int cBMPimage::bmpload( const char* filename ){FILE *fp;int bTrueClr=1;unsigned char *cp1, *cp2, *sp; int i, j;  int Width;  unsigned char *paletteIndex; if ((fp = fopen(filename,"rb+")) == NULL) // must be "rb" to indicate the position of the file while the pointer is moving!   {  printf("Can not open file\n");  system("pause");  exit(0);  }fread(&file,sizeof(unsigned short),1,fp);//??????????sp = (unsigned char*)&file;sp = sp+4;fread(sp,sizeof(struct tagBMPHEADER)-4,1,fp);fread(&info,sizeof(struct tagBMPINFOHEADER),1,fp);if (info.biBitCount==1||\info.biBitCount==4||\info.biBitCount==8){palette = (BMPRGBQUAD *)malloc(sizeof(BMPRGBQUAD)*(1<<info.biBitCount));fread(palette,sizeof(BMPRGBQUAD)*(1<<info.biBitCount),1,fp);bTrueClr = 0;}if (file.bfType != 0x4d42)  {  printf("The type of the image is not supported\n");  }  if (info.biCompression != 0)  {  printf("The compression type are not supported.\n");  }  if (file.bfSize != GetBmpSize(fp))  {  printf("The size of the file is not matched\n");  }  cp1 = (unsigned char *)&(file.bfType);  cp2 = cp1 + 1;  printf("%c", *cp1);  printf("%c\n", *cp2);  printf("File size: %lu\n", file.bfSize);  printf("Offset from the BOF to the virtual image data: %lu\n", file.bfOffset);  // print the info value.   printf("The size of the infoheader is: %lu\n", info.biSize);  printf("Width: %ld\n", info.biWidth);  printf("Height: %ld\n", info.biHeight);  printf("Planes: %d\n", info.biPlanes);  printf("Bit Depth: %d\n", info.biBitCount);  printf("Compression type: %lu\n", info.biCompression);  printf("Image data size: %lu\n", info.biSizeImage);  printf("XperMeter: %ld\n", info.biXplosPerMeter);  printf("YperMeter: %ld\n", info.biYplosPerMeter);  printf("Color used: %lu\n", info.biClrUsed);  printf("Important color: %lu\n", info.biClrImportant);  Width = (info.biWidth*info.biBitCount + 31)/8/4*4;//int pic_width = Width/4;// print the pixel of the imagedata   imagedata = (IMAGEDATA *)malloc( sizeof(unsigned char)*Width*info.biHeight);paletteIndex = (unsigned char *)malloc(sizeof(unsigned char)*Width*info.biHeight);  if (!bTrueClr)  {  fread(paletteIndex, sizeof(unsigned char)*Width*info.biHeight, 1, fp);  for (i = 0; i < info.biHeight; i++)  {  for (j = 0; j < Width; j++)  {  (*(imagedata + i * info.biHeight + j)).blue = palette[(BYTE)(*(paletteIndex + i*info.biHeight + j))].rgbBlue;  (*(imagedata + i * info.biHeight + j)).green = palette[(BYTE)(*(paletteIndex + i*info.biHeight + j))].rgbGreen;  (*(imagedata + i * info.biHeight + j)).red= palette[(BYTE)(*(paletteIndex + i*info.biHeight + j))].rgbRed;  }  }  }  else  {  fread(imagedata, sizeof(unsigned char)*Width*info.biHeight, 1, fp);}  fclose(fp);  //system("pause");  free(paletteIndex);  return 0;  }int cBMPimage::bmpcopypara( cBMPimage *pbmpimage ){file.bfOffset = pbmpimage->file.bfOffset;file.bfSize = pbmpimage->file.bfSize;file.bfType = pbmpimage->file.bfType;info.biBitCount = pbmpimage->info.biBitCount;info.biClrImportant = pbmpimage->info.biClrImportant;info.biClrUsed = pbmpimage->info.biClrUsed;info.biCompression = pbmpimage->info.biCompression;info.biHeight = pbmpimage->info.biHeight;info.biPlanes = pbmpimage->info.biPlanes;info.biSize = pbmpimage->info.biSize;info.biSizeImage = pbmpimage->info.biSizeImage;info.biWidth = pbmpimage->info.biWidth;info.biXplosPerMeter = pbmpimage->info.biXplosPerMeter;info.biYplosPerMeter = pbmpimage->info.biYplosPerMeter;if (pbmpimage->palette ==NULL){  palette = NULL;}else{int sizepale = sizeof(BMPRGBQUAD)*(1<<info.biBitCount);palette = (BMPRGBQUAD *)malloc(sizepale);memcpy(palette,pbmpimage->palette,sizepale);}return 1;}int cBMPimage::bmpsave( const char* filename ){FILE *fp = NULL;if (!(fp=fopen(filename,"wb+"))){printf("无法打开文件%s！\n",filename);return -1;}if(fwrite(&file.bfType,sizeof(WORD),1,fp)!=1){printf("Can not write bfType in the file header.\n");fclose(fp);return -1;}if(fwrite(&file.bfSize,sizeof(DWORD),1,fp)!=1){printf("Can not write bfSize in the file header.\n");fclose(fp);return -1;}if(fwrite(&file.Reserved1,sizeof(WORD),1,fp)!=1){printf("Can not write bfReserved1 in the file header.\n");fclose(fp);return -1;}if(fwrite(&file.Reserved2,sizeof(WORD),1,fp)!=1){printf("Can not write bfReserved2 in the file header.\n");fclose(fp);return -1;}if(fwrite(&file.bfOffset,sizeof(DWORD),1,fp)!=1){printf("Can not write bfOffBits in the file header.\n");fclose(fp);return -1;}if(fwrite(&info.biSize,sizeof(DWORD),1,fp)!=1){printf("Can not write biSize in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biWidth,sizeof(LONG),1,fp)!=1){printf("Can not write biWidth in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biHeight,sizeof(LONG),1,fp)!=1){printf("Can not write biHeight in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biPlanes,sizeof(WORD),1,fp)!=1){printf("Can not write biPlanes in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biBitCount,sizeof(WORD),1,fp)!=1){printf("Can not write biBitCount in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biCompression,sizeof(DWORD),1,fp)!=1){printf("Can not write biCompression in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biSizeImage,sizeof(DWORD),1,fp)!=1){printf("Can not write biSizeImage in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biXplosPerMeter,sizeof(LONG),1,fp)!=1){printf("Can not write biXPelsPerMeter in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biYplosPerMeter,sizeof(LONG),1,fp)!=1){printf("Can not write biYPelsPerMeter in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biClrUsed,sizeof(DWORD),1,fp)!=1){printf("Can not write biClrUsed in the info header.\n");fclose(fp);return -1;}if(fwrite(&info.biClrImportant,sizeof(DWORD),1,fp)!=1){printf("Can not write biClrImportant in the info header.\n");fclose(fp);return -1;}BMPRGBQUAD pal[256];for(int i=0;i<256;i++){pal[i].rgbReserve=0;pal[i].rgbBlue=i;pal[i].rgbGreen=i;pal[i].rgbRed=i;}if(info.biBitCount==8){if(fwrite(pal,sizeof(RGBQUAD),256,fp)!=256){printf("Error: can not write the color palette.\n");fclose(fp);return -1;}}int Width = (info.biWidth*info.biBitCount + 31)/8/4*4;int writenum = fwrite(imagedata,sizeof(unsigned char),info.biHeight*Width,fp);if(writenum!=info.biHeight*Width){printf("Error: can not write the pixel data.\n");fclose(fp);return -1;}fclose(fp);//printf("Save As the image successfully.\n");return 0;}

 

4.main.c

#include "cBMPimage.h"int main(){char *fp ="E:\\cudatest\\bmpread\\bmpread\\Debug\\a.bmp";cBMPimage image1,image2;image1.bmpload(fp);image2.bmpcopypara(&image1);image1.bmpsave("E:\\cudatest\\bmpread\\bmpread\\b.bmp");return 0;}

 注：在简略上述程序，只用于8位灰度图时，发现会出现读写错误。逐语句的去找问题，终于找到了。。。。

     在打开bmp文件时，若用fopen函数，mode使用“r+”时，会默认用文本文件方式打开bmp文件，这时，读取颜色表不成功（只读到了0~0x19）。

     所以在打开bmp文件时，一定要用“rb+”，即以二进制方式打开bmp文件。

   为什么在读到0x19 0x19 0x19 0xff 后会结束呢？

  因为0x19后是0x1a，0x1A在ASCII码中代表EOF，在过去，ASCII码EOF曾经在unix/linux中被作为文件结束符使用，微软继承了这个传统，也以EOF作为文件的结束符

  如何解决这个问题？其实标准已经给出了其中一种解决方法，由于二进制方式的输入输出是一一对应的，字符不会产生变化，那么用二进制读取就不会产生这个问题，事实也证明是可以的，只是存在一点麻烦，由于windows下会把/n转换为/r/n，二进制读取时必须对此转换进行堙别和还原，这会增加代码的复杂性，这种麻烦很让人讨厌。