GraphicsPath and DrawPath - remove intersecting lines

Question

The following code draws a cross:

using (SolidBrush brush = new SolidBrush(Color.FromArgb(192, 99, 104, 113)))
{
    using(GraphicsPath path = new GraphicsPath())
    {
        path.AddRectangle(new Rectangle(e.ClipRectangle.X + (e.ClipRectangle.Width - 40) / 2, e.ClipRectangle.Y, 40, e.ClipRectangle.Height));
        path.AddRectangle(new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y + (e.ClipRectangle.Height - 40) / 2, e.ClipRectangle.Width, 40));
        path.FillMode = FillMode.Winding;
        e.Graphics.DrawPath(Pens.DimGray, path);
    }
}

I would like to do it like this:

I tried using Flatten();and CloseAllFigures();, but they do not work.

I am looking for an effect similar to Union:

Is this possible with GraphicsPath?

Answer 1

You can use regions. But you have to use the FrameRgn API in GDI to draw a frame region if there are no other solutions.

        Graphics g = e.Graphics;
        using (SolidBrush brush = new SolidBrush(Color.FromArgb(192, 99, 104, 113)))
        {
            using (GraphicsPath path = new GraphicsPath())
            {
                path.AddRectangle(new Rectangle(e.ClipRectangle.X + (e.ClipRectangle.Width - 40) / 2, e.ClipRectangle.Y, 40, e.ClipRectangle.Height));
                path.AddRectangle(new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y + (e.ClipRectangle.Height - 40) / 2, e.ClipRectangle.Width, 40));
                path.FillMode = FillMode.Winding;
                using (Region region = new Region(path))
                {
                    IntPtr reg = region.GetHrgn(g);
                    IntPtr hdc = g.GetHdc();
                    IntPtr brushPtr = Win32.GetStockObject(Win32.WHITE_BRUSH);
                    IntPtr oldbrushPtr = Win32.SelectObject(hdc, brushPtr);
                    Win32.FrameRgn(hdc, reg, brushPtr, 1, 1);
                    Win32.DeleteObject(brushPtr);
                    Win32.SelectObject(hdc, oldbrushPtr);
                    region.ReleaseHrgn(reg);
                    g.ReleaseHdc();
                }
            }
        }

Answer 2

I know this is not an ideal solution, but take it as one of the options:

        using (SolidBrush brush = new SolidBrush(Color.FromArgb(192, 99, 104, 113)))
        {
            using (GraphicsPath path = new GraphicsPath())
            {
                var rect1 = new Rectangle(e.ClipRectangle.X + (e.ClipRectangle.Width - 40) / 2, e.ClipRectangle.Y, 40, e.ClipRectangle.Height - 1);
                var rect2 = new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y + (e.ClipRectangle.Height - 40) / 2, e.ClipRectangle.Width - 1, 40);
                path.AddRectangle(rect1);
                path.AddRectangle(rect2);
                e.Graphics.DrawPath(Pens.DimGray, path);

                var bgRect1 = new Rectangle(rect1.X + 1, rect1.Y + 1, rect1.Width - 1, rect1.Height - 1);
                var bgRect2 = new Rectangle(rect2.X + 1, rect2.Y + 1, rect2.Width - 1, rect2.Height - 1);
                using (GraphicsPath backgroundPath = new GraphicsPath())
                {
                    backgroundPath.AddRectangle(bgRect1);
                    backgroundPath.AddRectangle(bgRect2);
                    e.Graphics.FillPath(Brushes.White, backgroundPath);
                }
            }
        }

This is the result:

Answer 3

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Answer 4

, , . , Exclude, Intersect Xor !:)

    private void Form1_Paint(object sender, PaintEventArgs e)
    {
        GraphicsPath Shape1 = new GraphicsPath();
        Shape1.AddRectangle(new Rectangle(e.ClipRectangle.X + (e.ClipRectangle.Width - 40) / 2, e.ClipRectangle.Y, 40, e.ClipRectangle.Height));

        GraphicsPath Shape2 = new GraphicsPath();
        Shape2.AddRectangle(new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y + (e.ClipRectangle.Height - 40) / 2, e.ClipRectangle.Width, 40));

        Region UnitedRegion = new Region();
        UnitedRegion.MakeEmpty();
        UnitedRegion.Union(Shape1);
        UnitedRegion.Union(Shape2);

        e.Graphics.FillRegion(Brushes.Black, UnitedRegion);
    }