I've made the wrong assumption that if I use Graphics.DrawEllipse
to draw a circle with radius equal to 2px with pen of width about 2px, it will result in a filled circle with diameter about 4-5 px being drawn.
But I've found out that I actually can't rely on the width of the pen while drawing a circle this way. This method is meant only for drawing of border of this shape, thus for drawing filled ellipse it's much better to use Graphics.FillEllipse
.
Another quite important fact to consider is that both of mentioned functions take as parameters coordinates that specify "upper-left corner of the rectangle that specifies the boundaries of the ellipse", so I should subtract half of the radius from both coordinates to make sure the original coordinates specify the middle of this circle.
Here's the new code:
// draw the white background:
SolidBrush whiteBrush(Color::White);
graphics.FillRectangle(&whiteBrush, 0, 0, w, h);
// draw stroke:
Pen blackBrush(Color::Black);
std::vector<Gdiplus::Point> stroke = getStroke();
for (UINT i = 0; i < stroke.size(); ++i)
graphics.FillEllipse(&blackBrush, stroke[i].X - 2, stroke[i].Y - 2, 4, 4);
// draw original points:
Pen redBrush(Color::Red);
std::vector<Gdiplus::Point> origStroke = getOriginalStroke();
for (UINT i = 0; i < origStroke.size(); ++i)
graphics.FillRectangle(&redBrush, origStroke[i].X, origStroke[i].Y, 1, 1);
which yields following result:
So in case someone will face the same problem as I did, the solution is: