The document describes how to add paint functionality to a MFC application by tracking mouse movement and drawing lines. It involves adding x and y integer variables to track mouse position, initializing them in the constructor, updating them on mouse move events, and redrawing on right click by calling RedrawWindow(). Lines are drawn between the current and previous mouse positions on left mouse button drag events using the stored x and y values.

1. Paint

5. Add the folowing member variables:
………………
DECLARE_MESSAGE_MAP()
public:
int x;
int y;
};
Var name Var type Class Access type
x int CPaintView public
y int CPaintView public

6. • Initialize the var in the constructor of the
CPaintView class:
CPaintView::CPaintView() noexcept
{
// TODO: add construction code here
x = 0;
y = 0;
}

10. void CPaintView::OnMouseMove(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
CClientDC dc(this);
if (nFlags == MK_LBUTTON)
{
dc.MoveTo(x, y);
dc.LineTo(point.x, point.y);
}
x = point.x;
y = point.y;
CView::OnMouseMove(nFlags, point);
}

14. void CPaintView::OnRButtonDown(UINT nFlags,
CPoint point)
{
// TODO: Add your message handler code here
//and/or call default
RedrawWindow();
CView::OnRButtonDown(nFlags, point);
}