A circle is displayed and can be moved

This question is simple , but “ Five zang organs ”.

1, demand
a, Display circle
b, Move circle
2, Outline design
a, The center and radius of the circle are known , Display circle
b, Click the circle to start moving , Click end move again
3, Detailed design
a, If the distance from a point to the center of the circle is equal to （ Less than ） radius , Then on the circle （ Inside the circle ）.
b, It is displayed with dotted lines during the movement .
4, code
1, Create a new single document program Yuan.
2,CYuanView Add three variables in :
 CPoint  m_pt;// center of a circle
 int  m_iR;// radius
 BOOL m_bMove;// Is it moving
3, Initialization in constructor .

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       CYuanView::CYuanView()
       
       
 {
       
       
  m_pt = CPoint(60,60);
       
       
  m_iR = 50 ;
       
       
  m_bMove =
       
       
  FALSE ;
       
       
 }
      
      
      
      

       
       
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4, Display circle

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       void CYuanView::OnDraw(CDC* pDC)
       
       
{
       
       
  CPen pen(m_bMove?PS_DOT:PS_SOLID,1,RGB(0,0,0));
       
       
  pDC->SelectObject(&pen);
       
       
  pDC->Ellipse(m_pt.x-m_iR,m_pt.y-m_iR,m_pt.x+m_iR,m_pt.y+m_iR);
       
       
 }
       
       
 
      
      
      
      

       
       
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5, Move

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       #include "math.h"
       
       
 int GetJuLi(const CPoint pt1,const CPoint pt2) // The distance between two points 
       
       
 {
       
       
  return sqrt((pt1.x-pt2.x)*(pt1.x-pt2.x) + (pt1.y-pt2.y)*(pt1.y-pt2.y));
       
       
 }void CYuanView::OnLButtonDown(UINT nFlags, CPoint point) 
       
       
 { 
       
       
  CView::OnLButtonDown(nFlags, point);
       
       
  if( !m_bMove )
       
       
  {// Start moving 
       
       
   if(GetJuLi(point,m_pt) <= m_iR)
       
       
   {
       
       
    m_pt = point;
       
       
    m_bMove = TRUE ;
       
       
   }
       
       
  }
       
       
  else
       
       
  {// End move 
       
       
   m_pt = point;
       
       
   m_bMove = FALSE ;
       
       
   Invalidate();
       
       
  }
       
       
 }
       
       
 6, In the process of moving 
       
       
 void CYuanView::OnMouseMove(UINT nFlags, CPoint point) 
       
       
 {
       
       
  CView::OnMouseMove(nFlags, point);
       
       
  if( m_bMove )
       
       
  {
       
       
   m_pt = point ;
       
       
   Invalidate();
       
       
  }
       
       
 }
      
      
      
      

       
       
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Known problems ：
Cannot cancel after the move starts .

 

Source code :​ ​http://pan.baidu.com/share/link?shareid=574458&uk=4280148702​​