How transparency works in drawing rectangle(border or whole area)(C#)?

Question

I have a colormap plot and want to apply mesh dimensions on the picture plot. This request was successfully done by using the following code:

// draw mesh pattern
                        Pen transPen = new Pen(Color.FromArgb(128, 150, 150, 150),2);
                        g.DrawRectangle(transPen, (float)X,
                            (float)Y,
                            (float)dx,
                            (float)dy);

// draw contour square (brush , x , y , dx , dy)
                        g.FillRectangle(myContourBrush,
                            (float)X,
                            (float)Y,
                            (float)dx,
                            (float)dy);

Now my question is : the first transparent rectangle are transparent just in border area or all rectangle area? I don't want to affect colormap color, I just want to have mesh pattern.

Answer 1

The DrawRectangle method only draws the edge. If you want to fill it, you must use FillRectangle . Take a look for yourself. You might have to zoom in quite a bit to notice the color change.