位图的像素操作练习（2012-05-25）

很久没有较长篇的代码练习了，今天偷闲回顾练习了一下位图文件的像素操作，备忘，参考了：

水平翻转，垂直翻转，转灰度:

void BMPOpt(){

BITMAPFILEHEADER fhd;

BITMAPINFOHEADER ihd;

BYTE *pDat=NULL;

CString sfnm("e:\\t.bmp");

CFile file;

if(file.Open(sfnm, CFile::modeRead)){

try{

file.Read(&fhd, sizeof(BITMAPFILEHEADER));

file.Read(&ihd, sizeof(BITMAPINFOHEADER));

int offset = fhd.bfOffBits;

int high = ihd.biHeight,

wide = ihd.biWidth,

w4B  = ((wide*3+3)/4)*4;

int bits = ihd.biBitCount;

int len = high*w4B + w4B*2; //*wide*3;

pDat = (BYTE*)malloc(len);

if(pDat){

memset(pDat, 0, len);

}else{

throw "malloc err";

}

BYTE *pLine = pDat+high*w4B;

file.Read(pDat, len);

file.Close();

//{{// flip H::

for(int i=0; i<high/2; i++){

memcpy(pLine, pDat+i*w4B, w4B);

memcpy(pDat+i*w4B, pDat+(high-1-i)*w4B, w4B);

memcpy(pDat+(high-1-i)*w4B, pLine, w4B);

}

CFile f2;

if(f2.Open("e:\\t2.bmp", CFile::modeCreate|CFile::modeWrite)){

f2.Write(&fhd, sizeof(BITMAPFILEHEADER));

f2.Write(&ihd, sizeof(BITMAPINFOHEADER));

f2.Write(pDat, high*w4B);

f2.Close();

}

//}// flip H;;

//{ flip V::

BYTE a=0, b=0, c=0;

for(int i=0; i<high; i++){

pLine = pDat+i*w4B;

for(int j=0; j<wide/2; j++){

a=pLine[j*3];

b=pLine[j*3+1];

c=pLine[j*3+2];

int pos = (wide-1-j)*3;

pLine[j*3]   = pLine[pos];

pLine[j*3+1] = pLine[pos+1];

pLine[j*3+2] = pLine[pos+2];

pLine[pos]   = a;

pLine[pos+1] = b;

pLine[pos+2] = c;

}

}

CFile f3;

if(f3.Open("e:\\t3.bmp", CFile::modeCreate|CFile::modeWrite)){

f3.Write(&fhd, sizeof(BITMAPFILEHEADER));

f3.Write(&ihd, sizeof(BITMAPINFOHEADER));

f3.Write(pDat, high*w4B);

f3.Close();

}

//}} flip V;;

//{//make gray bmp, 8bits:

int gwide = (wide+3)/4*4;

int glen = high*gwide;

BYTE *pdat2 = (BYTE*)malloc(glen+4);

memset(pdat2, 0, glen);

BYTE *p8ln = NULL;

BYTE *p24ln = NULL;

//BYTE a=0, b=0, c=0;

for(int i=0; i<high; i++){

p8ln = pdat2 + i*gwide;

p24ln = pDat + i*w4B;

for(int j=0; j<wide; j++){

a=p24ln[j*3];

b=p24ln[j*3+1];

c=p24ln[j*3+2];

p8ln[j] = (a+b+c)/3;

}

}

RGBQUAD rgb[256] = {0};

int rgblen = sizeof(rgb);

fhd.bfSize = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+gwide*high + sizeof(rgb);

ihd.biBitCount = 8;

ihd.biSize = sizeof(BITMAPINFOHEADER);

ihd.biSizeImage = 0;

ihd.biClrUsed = 256;

for(int n=0; n<0xff; n++){

rgb[n].rgbBlue = n;

rgb[n].rgbGreen = n;

rgb[n].rgbRed  = n;

}

CFile f4;

if(f4.Open("e:\\t4.bmp", CFile::modeCreate|CFile::modeWrite)){

f4.Write(&fhd, sizeof(BITMAPFILEHEADER));

f4.Write(&ihd, sizeof(BITMAPINFOHEADER));

f4.Write(&rgb, sizeof(rgb));

f4.Write(pdat2, glen);

f4.Close();

}

free(pdat2);

pdat2 = NULL;

//} //make gray bmp, 8bits;;

if(pDat!=NULL){

free(pDat);

pDat = NULL;

}

AfxMessageBox("OK");

}catch(CException *e){

CString sErr;

sErr.Format("Read Err\nerr code=%d", GetLastError());

//e->GetErrorMessage(sErr);

AfxMessageBox(sErr);

}

}else{

AfxMessageBox("Open file fail");

}

}