// An example program in which the
// user can draw boxes on the screen.
//
#include <cv.h>
#include <highgui.h>

// Define our callback which we will install for
// mouse events.
//
void my_mouse_callback(int event, int x, int y, int flags, void* param);

CvRect box;
bool drawing_box = false;

// A litte subroutine to draw a box onto an image
//
void draw_box( IplImage* img, CvRect rect ) 
{
  cvRectangle (img, cvPoint(box.x,box.y), cvPoint(box.x+box.width,box.y+box.height), CV_RGB(0xff,0x00,0x00), 1, 8, 0);  /* red box*/
}

//
// MAIN
//
int main( int argc, char* argv[] ) 
{
  box = cvRect(-1,-1,0,0);
  IplImage* image = cvCreateImage(cvSize(200,200),IPL_DEPTH_8U, 3);
  cvZero( image );
  IplImage* temp = cvCloneImage( image );
  cvNamedWindow( "Box Example" );
  // Here is the crucial moment that we actually install
  // the callback. Note that we set the value ‘param’ to
  // be the image we are working with so that the callback
  // will have the image to edit.
  //
  cvSetMouseCallback( "Box Example", my_mouse_callback,(void*) image);
  // The main program loop. Here we copy the working image
  // to the ‘temp’ image, and if the user is drawing, then
  // put the currently contemplated box onto that temp image.
  // display the temp image, and wait 15ms for a keystroke,
  // then repeat…
  //
  while( 1 ) 
  {
    cvCopyImage( image, temp );
    if( drawing_box ) draw_box( temp, box );
    cvShowImage( "Box Example", temp );
    if( cvWaitKey( 15 )==27 ) break;
  }
  // Be tidy
  //
  cvReleaseImage( &image );
  cvReleaseImage( &temp );
  cvDestroyWindow( "Box Example" );
}


// This is our mouse callback. If the user
// presses the left button, we start a box.
// when the user releases that button, then 
// add the box to the current image. When th
// mouse is dragged (with the button down) w
// resize the box.
//
void my_mouse_callback( int event, int x, int y, int flags, void *param ) 
{
  IplImage* image = (IplImage*) param;

  switch( event ) 
  {
    case CV_EVENT_MOUSEMOVE: 
	{
      if( drawing_box ) 
	  {
        box.width  = x-box.x;
        box.height = y-box.y;
      }
    }
    break;
    case CV_EVENT_LBUTTONDOWN: 
	{
      drawing_box = true;
      box = cvRect(x, y, 0, 0);
    }
    break;
    case CV_EVENT_LBUTTONUP: 
	{
      drawing_box = false;
      if(box.width<0) 
	  {
        box.x+=box.width;
        box.width *=-1;
      }
      if(box.height<0) 
	  {
        box.y+=box.height;
        box.height*=-1;
      }
      draw_box(image, box);
    }
    break;
  }
}