OpenCV学习——Highgui演示－简单绘制矩形

// An example program in which the

// user can draw boxes on the screen.

//

/* License:

   Oct. 3, 2008

   Right to use this code in any way you want without warrenty, support or any guarentee of it working.

   BOOK: It would be nice if you cited it:

   Learning OpenCV: Computer Vision with the OpenCV Library

     by Gary Bradski and Adrian Kaehler

     Published by O'Reilly Media, October 3, 2008

 

   AVAILABLE AT:

     http://www.amazon.com/Learning-OpenCV-Computer-Vision-Library/dp/0596516134
     Or: http://oreilly.com/catalog/9780596516130/
     ISBN-10: 0596516134 or: ISBN-13: 978-0596516130   

   OTHER OPENCV SITES:

   * The source code is on sourceforge at:

     http://sourceforge.net/projects/opencvlibrary/
   * The OpenCV wiki page (As of Oct 1, 2008 this is down for changing over servers, but should come back):

     http://opencvlibrary.sourceforge.net/
   * An active user group is at:

     http://tech.groups.yahoo.com/group/OpenCV/
   * The minutes of weekly OpenCV development meetings are at:

     http://pr.willowgarage.com/wiki/OpenCV
*/

#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),

    cvScalar(0xff,0x00,0x00)    /* red */

  );

}

 

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 we

// add the box to the current image.  When the

// mouse is dragged (with the button down) we

// 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;  

  }

}