moving object using slider openCV c++ - c++

Question

I'm very new to OpenCV (c++), my lecturer ask me to make a simple slider that every position in slider have different place in the window. My code below can move the object in window based on slider position but when i moved the slider the old position still there. So it looks like a duplicate not move. Can anyone help me on this problem?? Are there a way to solve this problem or I must change the code completely??
#include "stdafx.h"
#include "cv.h"
#include "ml.h"
#include "cxcore.h"
#include "highgui.h"
int g_switch_value = 0;
int colorInt = 0;
void switch_callback( int position ){
if( position == 0 ){
colorInt = 0;
}else{
colorInt = 1;
}
}
int _tmain(int argc, _TCHAR* argv[])
{
const char* name = "Change the color of circle in the picture";
int radius = 30;
int thickness = 12;
int connectivity = 8;
cvscalar red = cv_RGB(0,0,255);
IplImage* src1 = cvLoadImage( "E:/2.jpg" );
CvPoint pt1 = cvPoint(405,195);
CvPoint pt2 = cvPoint(620,400);
cvNamedWindow( name, 1 );
cvShowImage(name, src1);
cvCreateTrackbar( "Change", name, &g_switch_value, 1, switch_callback );
while( 1 ) {
if( colorInt == 0) {
cvCircle(src1,pt1,radius,red,thickness,connectivity);}
else {
cvCircle(src1,pt2,radius,red,thickness,connectivity); }
colorInt == 1;
cvShowImage(name, src1);
if( cvWaitKey( 15 ) == 27 ) break;
}
cvReleaseImage( &src1 );
cvDestroyWindow( name );
return 0; }

Answer 1

Drawing overwrite the image, then you should keep a fresh copy for each different painting.
The easier way:
IplImage* src1 = cvLoadImage( "..." );
IplImage* src2 = cvLoadImage( "..." );
...
while( 1 ) {
if( colorInt == 0) {
cvShowImage(name, src1);
cvCircle(src1,pt1,radius,red,thickness,connectivity);
}
else {
cvShowImage(name, src2);
cvCircle(src2,pt2,radius,red,thickness,connectivity);
}
if( cvWaitKey( 15 ) == 27 ) break;
}
cvReleaseImage( &src1 );
cvReleaseImage( &src2 );