## 图像旋转算法与实现

x1 = x0 - w/2; y1 = -y0 + h/2;

x0=rcosb；y0=rsinb

x1 = rcos(b-a) = rcosbcosa+rsinbsina=x0cosa+y0sina；

y1=rsin(b-a)=rsinbcosa-rcosbsina=-x0sina+y0cosa；

  1 #include "stdafx.h"  2 #include <stdio.h>  3 #include <string>  4 #include <math.h>  5 #include <windows.h>  6  using namespace std;  7   8  #define PI 3.1415926535  9 //角度到弧度转化 10 #define RADIAN(angle) ((angle)*PI/180.0) 11  12 void Rotation(const string& srcFile,const string& desFile,int angle) 13 { 14     BITMAPFILEHEADER bmfHeader; 15     BITMAPINFOHEADER bmiHeader; 16      17     FILE *pFile; 18     if ((pFile = fopen(srcFile.c_str(),"rb")) == NULL) 19     { 20         printf("open bmp file error."); 21         exit(-1); 22     } 23     //读取文件和Bitmap头信息 24     fseek(pFile,0,SEEK_SET); 25     fread(&bmfHeader,sizeof(BITMAPFILEHEADER),1,pFile); 26     fread(&bmiHeader,sizeof(BITMAPINFOHEADER),1,pFile); 27     //先不支持小于16位的位图 28     int bitCount = bmiHeader.biBitCount; 29     if (bitCount < 16) 30     {         31         exit(-1); 32     } 33     int srcW = bmiHeader.biWidth; 34     int srcH = bmiHeader.biHeight; 35     //原图像每一行去除偏移量的字节数 36     int lineSize = bitCount * srcW / 8; 37     //偏移量，windows系统要求每个扫描行按四字节对齐 38     int alignBytes = ((bmiHeader.biWidth * bitCount + 31) & ~31) / 8L 39         - bmiHeader.biWidth * bitCount / 8L; 40     //原图像缓存 41     int srcBufSize = lineSize * srcH; 42     BYTE* srcBuf = new BYTE[srcBufSize]; 43     int i,j; 44     //读取文件中数据 45     for (i = 0; i < srcH; i++) 46     {         47         fread(&srcBuf[lineSize * i],lineSize,1,pFile); 48         fseek(pFile,alignBytes,SEEK_CUR); 49     } 50     //以图像中心为原点左上角，右上角，左下角和右下角的坐标,用于计算旋转后的图像的宽和高 51     POINT pLT,pRT,pLB,pRB; 52     pLT.x = -srcW/2;pLT.y = srcH/2; 53     pRT.x = srcW/2;pRT.y = srcH/2; 54     pLB.x = -srcW/2;pLB.y = -srcH/2; 55     pRB.x = srcW/2; pRB.y = -srcH/2; 56     //旋转之后的坐标 57     POINT pLTN,pRTN,pLBN,pRBN; 58     double sina = sin(RADIAN(angle)); 59     double cosa = cos(RADIAN(angle)); 60     pLTN.x = pLT.x*cosa + pLT.y*sina;     61     pLTN.y = -pLT.x*sina + pLT.y*cosa; 62     pRTN.x = pRT.x*cosa + pRT.y*sina; 63     pRTN.y = -pRT.x*sina + pRT.y*cosa; 64     pLBN.x = pLB.x*cosa + pLB.y*sina; 65     pLBN.y = -pLB.x*sina + pLB.y*cosa; 66     pRBN.x = pRB.x*cosa + pRB.y*sina; 67     pRBN.y = -pRB.x*sina + pRB.y*cosa; 68     //旋转后图像宽和高 69     int desWidth = max(abs(pRBN.x - pLTN.x),abs(pRTN.x - pLBN.x)); 70     int desHeight = max(abs(pRBN.y - pLTN.y),abs(pRTN.y - pLBN.y)); 71     //分配旋转后图像的缓存 72     int desBufSize = ((desWidth * bitCount + 31) / 32) * 4 * desHeight; 73     BYTE *desBuf = new BYTE[desBufSize]; 74     //将所有像素都预置为白色 75     memset(desBuf,255,desBufSize); 76     //新图像每一行字节数，带有偏移量 77     int desLineSize = ((desWidth * bitCount + 31) / 32) * 4;         78     //通过新图像的坐标，计算对应的原图像的坐标 79     for (i = 0; i < desHeight; i++) 80     {         81         for (j = 0; j < desWidth; j++) 82         { 83             //转换到以图像为中心的坐标系，并进行逆旋转 84             int tX = (j - desWidth / 2)*cos(RADIAN(360 - angle)) + (-i + desHeight / 2)*sin(RADIAN(360 - angle)); 85             int tY = -(j - desWidth / 2)*sin(RADIAN(360 - angle)) + (-i + desHeight / 2)*cos(RADIAN(360 - angle)); 86             //如果这个坐标不在原图像内，则不赋值 87             if (tX > srcW / 2 || tX < -srcW / 2 || tY > srcH / 2 || tY < -srcH / 2) 88             { 89                 continue; 90             } 91             //再转换到原坐标系下 92             int tXN = tX + srcW / 2; int tYN = abs(tY - srcH / 2); 93             //值拷贝 94             memcpy(&desBuf[i * desLineSize + j * bitCount / 8],&srcBuf[tYN * lineSize + tXN * bitCount / 8],3);             95         } 96     } 97  98     //创建目标文件 99     HFILE hfile = _lcreat(desFile.c_str(),0);    100     //文件头信息101     BITMAPFILEHEADER nbmfHeader;    102     nbmfHeader.bfType = 0x4D42;103     nbmfHeader.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER)104         + desWidth * desHeight * bitCount / 8;105     nbmfHeader.bfReserved1 = 0;106     nbmfHeader.bfReserved2 = 0;107     nbmfHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);108     //Bitmap头信息109     BITMAPINFOHEADER   bmi; 110     bmi.biSize=sizeof(BITMAPINFOHEADER); 111     bmi.biWidth=desWidth; 112     bmi.biHeight=desHeight; 113     bmi.biPlanes=1; 114     bmi.biBitCount=bitCount; 115     bmi.biCompression=BI_RGB; 116     bmi.biSizeImage=0; 117     bmi.biXPelsPerMeter=0; 118     bmi.biYPelsPerMeter=0; 119     bmi.biClrUsed=0; 120     bmi.biClrImportant=0; 121     122     //写入文件头信息123     _lwrite(hfile,(LPCSTR)&nbmfHeader,sizeof(BITMAPFILEHEADER));124     //写入Bitmap头信息125     _lwrite(hfile,(LPCSTR)&bmi,sizeof(BITMAPINFOHEADER));126     //写入图像数据127     _lwrite(hfile,(LPCSTR)desBuf,desBufSize);128     _lclose(hfile);129 }130 131 int main(int argc, char* argv[])132 {133     FILE *pFile;134     if ((pFile = fopen("e://t.bmp","rb")) == NULL)135     {136         printf("open bmp file error.");137         return -1;138     }139     string srcFile("e://t.bmp");140     string desFile("e://Rotation.bmp");141     Rotation(srcFile,desFile,150);142     system("pause");143     return 0;144 }

posted on 2011-05-15 18:26  落叶的思维  阅读(20794)  评论(5编辑  收藏  举报