Visual C++ and MFC Programming 2nd Edition

Visual C++ and MFC Fundamentals Chapter 7: GDI Accessories and Tools

6.3.4 Polygons................................................................................................

The polylines we have used so far were drawn by defining the starting point of the first

line and the end point of the last line and there was no relationship or connection between

these two extreme points. A polygon is a closed polyline. In other words, it is a polyline

defined so that the end point of the last line is connected to the start point of the first line.

To draw a polygon, you can use the CDC::Polygon() method. Its syntax is:

BOOL Polygon(LPPOINT lpPoints, int nCount);

This member function uses the same types of arguments as the Polyline() method. The

only difference is on the drawing of the line combination. Here is an example:

void CExoView::OnDraw(CDC* pDC)

{

CPoint Pt[7];

Pt[0] = CPoint(20, 50);

Pt[1] = CPoint(180, 50);

Pt[2] = CPoint(180, 20);

Pt[3] = CPoint(230, 70);

Pt[4] = CPoint(180, 120);

Pt[5] = CPoint(180, 90);

Pt[6] = CPoint(20, 90);

pDC->Polygon(Pt, 7);

}

Practical Learning: Drawing Polygons

To draw some polygons, change the program as follows:
void CView1View::OnPaint()
{
CPaintDC dc(this); // device context for painting

// TODO: Add your message handler code here
CPoint PtLine[] = { CPoint( 50, 50), CPoint(670, 50),
CPoint(670, 310), CPoint(490, 310),
CPoint(490, 390), CPoint(220, 390),
CPoint(220, 310), CPoint( 50, 310),
CPoint( 50, 50) };

CPoint Bedroom1[] = { CPoint( 55, 55), CPoint(175, 55),
CPoint(175, 145), CPoint( 55, 145)};
CPoint Closets[] = { CPoint( 55, 150), CPoint(145, 150),
CPoint(145, 205), CPoint( 55, 205) };
CPoint Bedroom2[] = { CPoint(55, 210), CPoint(160, 210),
CPoint(160, 305), CPoint(55, 305) };

dc.MoveTo(PtLine[0]);
dc.LineTo(PtLine[1]);
dc.LineTo(PtLine[2]);
dc.LineTo(PtLine[3]);
dc.LineTo(PtLine[4]);