this is my form and I'm trying to make it so the diagonal line in the middle divides the left and the right parts of my form evenly. The line is drawn in a separate panel, with a script instructing it where to position the line (also, the background of this panel was set to transparent). The left part of my form is another panel as well as the black part in the upper right corner. The login elements (the email and password fields, the register and sign-in buttons, etc) are attached to the form itself.

CodePudding user response：

I would put this into an own user control. Afterwards you could set everything through ForeColor, BackgroundColor, Thickness and RightToLeft:

public class DiagonalSeparator : UserControl
{
    private int thickness = 3;

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        using (Graphics g = e.Graphics)
        {
            g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            var p = new Pen(ForeColor, thickness);
            var point1 = RightToLeft == RightToLeft.No ? new Point(0, 0) : new Point(Width, 0);
            var point2 = RightToLeft == RightToLeft.No ? new Point(Width, Height) : new Point(0, Height);
            g.DrawLine(p, point1, point2);
        }
    }

    [DefaultValue(3)]
    [Description("The thickness of the drawn line"), Category("Appearance")]
    [Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
    public int Thickness
    {
        get
        {
            return thickness;
        }

        set
        {
            thickness = value;
            Invalidate();
        }
    }
}

This control can then be used as any other control within the designer and you can check if the visualization works as expected.