【OpenCV学习】Bresenham算法

/*
 * =====================================================================================
 *
 *       Filename:  linebresenham2.c
 *
 *    Description:  A program for bresenham ,any point you want
 *
 *        Version:  1.0
 *        Created:  01/08/2009 10:36:37 AM
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Futuredaemon (BUPT), gnuhpc@gmail.com
 *        Company:  BUPT_UNITED
 *
 * =====================================================================================
 */
#include <cv.h>
#include <highgui.h>
#include <cmath>
#include <cstring>
#include <cstdio>
#include <iostream>

using namespace std;


void Mouse( int event, int x, int y, int flags ,void *param);


void DRAW_LINE(CvPoint *p1, CvPoint *p2);
int CHECK_DIRECTION(char *str ,CvPoint *p1, CvPoint *p2);

void PUT_PIXEL_X(CvPoint *p1, CvPoint *p2,int &sx, int &sy,int &dx, int &dy);
void PUT_PIXEL_Y(CvPoint *p1, CvPoint *p2,int &sx, int &sy,int &dx, int &dy);


CvSize window={300,300};//窗口大小 

CvPoint p1;
CvPoint p2;
int number;
IplImage *imgA;

int main( int argc, char **argv)
{

  imgA = cvCreateImage(window,IPL_DEPTH_8U,3);
  cvSet (imgA, cvScalarAll (0), 0);


  cvNamedWindow("window",CV_WINDOW_AUTOSIZE);
  cvShowImage("window",imgA);

  cvSetMouseCallback("window", Mouse);


  cvWaitKey(0); 

  cvReleaseImage( &imgA );
  cvDestroyWindow("window");

  return 0;
}

void Mouse( int event, int x, int y, int flags ,void *param = NULL) //记录点
{

  switch (event)
    {

    case CV_EVENT_LBUTTONDOWN:

      if (number == 0)
        {
          printf("p1:(%d,%d) /n",x,y);
          cvSet (imgA, cvScalarAll (0), 0);
          cvShowImage("window",imgA);

          p1.x = x;
          p1.y = y;
          number++;

        }
      else if (number == 1)
        {
          printf("p2:(%d,%d) /n",x,y);
          puts("---------------");
          p2.x = x;
          p2.y = y;
          number =0;

          DRAW_LINE(&p1,&p2);

        }

      cvShowImage("window",imgA);

      break;

    }

}

void DRAW_LINE(CvPoint *p1, CvPoint *p2)
{

  /*初始值代入*/
  int dx = abs(p1->x - p2->x);
  int dy = abs(p1->y - p2->y);

  int sx = CHECK_DIRECTION("x",p1,p2); //方向決定(x軸)
  int sy = CHECK_DIRECTION("y",p1,p2);//方向決定(y軸)

  if (dx >= dy)
    {
      PUT_PIXEL_X(p1,p2,sx,sy,dx,dy);
    }
  else
    {
      PUT_PIXEL_Y(p1,p2,sx,sy,dx,dy);
    }

}


/*方向决定*/
int CHECK_DIRECTION(char *str ,CvPoint *p1, CvPoint *p2)
{

  if (strncmp(str,"x",1)== 0)
    {
      if (p1->x >= p2->x)
        {
          return -1;
        }
      else
        {
          return 1;
        }

    }
  else if (strncmp(str,"y",1)== 0)
    {
      if (p1->y >= p2->y)
        {
          return -1;
        }
      else
        {
          return 1;
        }
    }
  else
    {
      printf("CHECK_DIRECTION is fault./n");
      std::exit(0);
    }

}


/*X軸方向画线*/
void PUT_PIXEL_X(CvPoint *p1, CvPoint *p2,int &sx, int &sy ,int &dx, int &dy)
{

  int a = 2*dy;
  int a1= a-2*dx;
  int e = a - dx;

  int x = p1->x;
  int y = p1->y;

  for (x = p1->x; (sx >=0 ? x<= p2->x : x>=p2->x) ;x+=sx) 
    {
      imgA->imageData[y*imgA->widthStep + x*3] = (signed char)255;
      imgA->imageData[y*imgA->widthStep + x*3+1] = (signed char)255;
      imgA->imageData[y*imgA->widthStep + x*3+2] = (signed char)255;

      if (e>=0)
        {
          y+=sy;
          e += a1;
        }
      else
        {
          e+=a;
        }
    }

}

/*Y軸方向画线*/
void PUT_PIXEL_Y(CvPoint *p1, CvPoint *p2,int &sx, int &sy ,int &dx, int &dy)
{
  int a = 2*dx;
  int a1= a-2*dy;
  int e = a - dy;

  int x = p1->x;
  int y = p1->y;

  for (y = p1->y; (sy >=0 ? y<= p2->y : y>=p2->y) ;y+=sy)
    {

      imgA->imageData[y*imgA->widthStep + x*3] = (signed char)255;
      imgA->imageData[y*imgA->widthStep + x*3+1] = (signed char)255;
      imgA->imageData[y*imgA->widthStep + x*3+2] = (signed char)255;

      if (e>=0)
        {
          x+=sx;
          e += a1;
        }
      else
        {
          e+=a;
        }

    }
}