20130529_Lab_HW02

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

// add these two include files...

#include <cv.h>
#include <highgui.h>

#define W 900
#define H 720

void draw_line(IplImage *img2, int x1, int y1, int x2, int y2)
{
     int xtemp,ytemp ;
     if(x1 > x2)
     {
      xtemp = x1 ; x1 = x2 ; x2 = xtemp ;
      ytemp = y1 ; y1 = y2 ; y2 = ytemp ;
     }
     //To fix the bug that point can't be printed from right-side to left-side

     if(x1 == x2)
     {
     cvLine(
         img2, //CvArr* img,
         cvPoint((x1 + W/2), (-y1 + H/2)),  //CvPoint pt1,
         cvPoint((x1 + W/2), (-y2 + H/2)),  //CvPoint pt2,
         cvScalar(0, 255, 0, 0),  //CvScalar color,
         1, 8, 0
       ); //int thickness=1, int line_type=8, int shift=0 );
     }
     else
     {
     int dx = x2-x1;
     int dy = y2-y1;
     float m = (float)dy/dx;

     float x, y;  float IX, IY;
     for (x =  x1; x < x2; x = x + 0.01)
     {
       //y = m*x + y1 + 0.5; //Plus 0.5 to provide for m wasn't an integer.
       y = m * (x - x1) + y1 ;
       IX = x + W/2;
       IY = -y + H/2;
       //putpixel(x, y);

       cvLine(
         img2, //CvArr* img,
         cvPoint(IX, IY),  //CvPoint pt1,
         cvPoint(IX, IY),  //CvPoint pt2,
         cvScalar(0, 255, 0, 0),  //CvScalar color,
         1, 8, 0
       ); //int thickness=1, int line_type=8, int shift=0 );
      }
      }
}


int main(int argc, char *argv[])
{
  IplImage *img, *img2;      // Just like FILE *fptr ...

  img2 = cvCreateImage(cvSize(W, H), //CvSize size,
                       IPL_DEPTH_8U , //int depth,
                       3); //int channels

  printf("Channels %d depth %d \n", img2->nChannels, img2->depth);
  printf("The image Width by Height is %dX%d \n",
         img2->width,img2->height);
  printf("The image WidthStep %d \n", img2->widthStep);


     cvLine(
       img2, //CvArr* img,
       cvPoint(0, H/2),  //CvPoint pt1,
       cvPoint(W-1, H/2),  //CvPoint pt2,
       cvScalar(0, 0, 255, 0),  //CvScalar color,
       1, 8, 0); //int thickness=1, int line_type=8, int shift=0 );
     cvLine(
       img2, //CvArr* img,
       cvPoint(W/2, 0),  //CvPoint pt1,
       cvPoint(W/2, H-1),  //CvPoint pt2,
       cvScalar(0, 0, 255, 0),  //CvScalar color,
       1, 8, 0); //int thickness=1, int line_type=8, int shift=0 );

    /*              I              */
    draw_line(img2, 200, 200, 100, 100);
    /*              II             */
    draw_line(img2,-200, 200,-100, 100);
    /*              III            */
    draw_line(img2,-200,-200,-100,-100);
    /*              IIII           */
    draw_line(img2, 200,-200, 100,-100);
    /*              horizontal     */
    draw_line(img2,-200,-200, 200,-200);
    /*              vertical       */
    draw_line(img2,-100,-100,-100, 100);
    draw_line(img2, 100, 100, 100,-100);
    /*              large slope    */
    draw_line(img2, -20,-300,  20, 300);
    draw_line(img2,  20,-300, -20, 300);

    cvNamedWindow( "Fig2", 1 );
    cvShowImage("Fig2", img2 );


    cvWaitKey(0);
    cvDestroyWindow( "Fig2" );
    cvReleaseImage( &img2 );
    system("PAUSE");      return 0;


}