Question

Well I am trying to build a few small windows applications using MFC and trying to learn how things work, and while drawing a country’s flag I got stuck. Following lines of code draw three rectangles and a circle right at the center of middle rectangle, what need to do next is draw spokes in to circle, i.e 8 diameters separated by an angle of 45 degrees.

void CMainWindow::OnPaint (){
CPaintDC dc(this);
for (int i=0;i <=100;i+=50) {
    dc.SetBkMode(TRANSPARENT);
    CRect rect;
    CPen pen(PS_SOLID, 1, RGB(0,0,0));
    CPen *oldPen = dc.SelectObject(&pen);
    if (i == 0){
         CBrush brush(RGB(255,130,0));
         CBrush *oldBrush = dc.SelectObject(&brush);
         dc.Rectangle(75,(i+50),275,(i+100));
    }
    else if(i == 50) {
         CBrush brush(RGB(255,255,255));
         CBrush *oldBrush = dc.SelectObject(&brush);
         dc.Rectangle(75,(i+50),275,(i+100));
         CPen pen2(PS_SOLID, 1,RGB(0,0,255));
         CPen *oldPen = dc.SelectObject(&pen2);
         dc.Ellipse(150,100,200,150);
    }
    else {
         CBrush brush(RGB(34,139,34));
         CBrush *oldBrush = dc.SelectObject(&brush);
         dc.Rectangle(75,(i+50),275,(i+100));
    }
}

I have no clue how to do that, I tried to find it in the MFC library but no luck!

Answer 1

Here is an example of the sin() cos() method.
I didn’t see the point of putting the whole code block in a for loop, show I removed that part.

#include "math.h"
#define PI 3.1415926535898
void DrawIndiaFlag(CDC & dc , int x, int y)
{
    dc.SetBkMode(TRANSPARENT); 
    CRect rect; 
    CPen pen(PS_SOLID, 1, RGB(0,0,0)); 
    CPen *oldPen = dc.SelectObject(&pen); 

    {
        CBrush brush(RGB(255,130,0)); 
        CBrush *oldBrush = dc.SelectObject(&brush); 
        dc.Rectangle(x,(y),x+200,(y+50)); 
        dc.SelectObject(oldBrush);
    }

    {
        CBrush brush(RGB(255,255,255)); 
        CBrush *oldBrush = dc.SelectObject(&brush); 
        dc.Rectangle(x,(50+y),x+200,(y+100)); 
        CPen pen2(PS_SOLID, 1,RGB(0,0,255)); 
        CPen *oldPen = dc.SelectObject(&pen2); 
        dc.Ellipse(x+75,y+50,x+125,y+100); 

        // Draw spokes
        int nOriginX = x+100;
        int nOriginY = y+75;
        int nRadius = 25;
        int nSpokes = 24;
        double fAngle = 2*PI/nSpokes;

        for (int i =0; i<nSpokes; i++)
        {
            dc.MoveTo(nOriginX,nOriginY);
            int nX = (int)ceil(cos((fAngle)*i)*(nRadius)+nOriginX);
            int nY = (int)ceil(sin((fAngle)*i)*(nRadius)+nOriginY);
            dc.LineTo(nX,nY);
        }
        dc.SelectObject(oldPen);

    }

    {
        CBrush brush(RGB(34,139,34)); 
        CBrush *oldBrush = dc.SelectObject(&brush); 
        dc.Rectangle(x,(100+y),x+200,(150+y)); 
        dc.SelectObject(oldBrush);
    }

    dc.SelectObject(oldPen);
}