3/18/09

Visual c++ IntersectRect example tutorial




In this visual c++ IntersectRect Example we will learn how to use the mfc intersection function


The intersected rectangle hatched in Red

to get the exefile click here and download the file and get the complete project and thinks of additions you can make



To start


1- Start a new project and let us name it IntersectRectangle

2- chose single document and deselect printing and print view no need for them

3- Add the following members to the view class

public:

BOOL m_b_IsIntersected; // weather there is intersection or not

CRect m_Gray_Rectangle , m_Moving_Rectangle ,m_RectIntersection ;

// constant REct and moving and the rectangle of intersection

make your data members public to avoid using getters and setters

4-Initilize the values of the two rectangles in the constructor as follows


CIntersectrectangleView::CIntersectrectangleView():m_Moving_Rectangle(100,60,160,120),m_Gray_Rectangle(90,80,120,110),m_b_IsIntersected(FALSE)

5-

Add the following messege handler to the derived view class


WM_TIMER ,WM_LBUTONDOWN, WM_RBUTTONDOWN

and edit them as follows

start with Wm timer


void CIntersectrectangleView::OnTimer(UINT nIDEvent) {

if(m_Moving_Rectangle.right> 300) m_Moving_Rectangle.OffsetRect(-280,0) ;

m_Moving_Rectangle.OffsetRect(20,0);InvalidateRect(NULL,TRUE); CView::OnTimer(nIDEvent);}


and

void CIntersectrectangleView::OnRButtonDown(UINT nFlags, CPoint point) { KillTimer(1);



CView::OnRButtonDown(nFlags, point);}


and


void CIntersectrectangleView::OnLButtonDown(UINT nFlags, CPoint point) {

SetTimer(1, 450,NULL) ;

CView::OnLButtonDown(nFlags, point);

}


6-


edit the ondraw member functions as follows


void CIntersectrectangleView::OnDraw(CDC* pDC){






pDC->TextOut(60,13,"Press the right button to start moving the black rectangle and the right to stop it and notice the intersection");

pDC->SelectStockObject(BLACK_BRUSH);

pDC->Rectangle(m_Moving_Rectangle);

pDC->SelectStockObject(LTGRAY_BRUSH);

pDC->Rectangle(m_Gray_Rectangle);

LPRECT lp_move = m_Moving_Rectangle.operator LPRECT() ;

// cast the moving rect to LPRECT

LPRECT lp_gray = m_Gray_Rectangle.operator LPRECT() ;

// and so as to the grayrect



m_b_IsIntersected = m_RectIntersection.IntersectRect( lp_move ,lp_gray);
// find whethere there is intersection and draw the intersection rect with hatchbrush
if( m_b_IsIntersected){



CBrush brushHatch(HS_DIAGCROSS, RGB(255, 90, 0));

pDC->SelectObject(brushHatch) ;

pDC->Rectangle(m_RectIntersection);
//I used getstockobject because it is easier to use

}

8- finally build the application and see how it works





Do not forget to use casting when using intersictRect it only accept arguments of type LPRECT

for more example see the rest of the blog


I hope that you enjoyed this tutorial









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4 comments:

leave me messege