GradientPanel [WinForm]

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Runtime.InteropServices;

namespace System.Windows.Forms {

    [ComVisible(false)]
    public class GradientPanel:Panel {

        GradientPanelProperties _properties;

        public GradientPanel() {
            _properties = new GradientPanelProperties();
            _properties.GradientMode = LinearGradientMode.Horizontal;
            _properties.LeftColor = Color.Black;
            _properties.RightColor = Color.White;
        }

        protected override void OnResize(EventArgs eventargs) {
            if(base.DesignMode) {
                base.OnResize(eventargs);
                return;
            }
            this.Invalidate(true);
        }
        protected override void OnPaint(PaintEventArgs e) {
            this.PaintGradient(e.Graphics,e.ClipRectangle);
        }

        protected override void OnPaintBackground(PaintEventArgs pevent) {
            if(base.DesignMode) {
                this.PaintPanel(pevent.Graphics,pevent.ClipRectangle);
            }
        }

        protected void PaintGradient(Graphics graphics,Rectangle clipRectangle) {
            if(((graphics != null) && ((clipRectangle.Width != 0) && (clipRectangle.Height != 0))) && ((base.ClientRectangle.Width != 0) && (base.ClientRectangle.Height != 0))) {
                using(LinearGradientBrush brush = new LinearGradientBrush(base.ClientRectangle,this.LeftColor,this.RightColor,this.GradientMode)) {
                    if(this.BellShape) {
                        brush.SetSigmaBellShape(0.5f,1f);
                    }
                    else if(this.TriangleShape) {
                        brush.SetBlendTriangularShape(0.5f,1f);
                    }
                    graphics.FillRectangle(brush,clipRectangle);
                }
            }
        }

        public virtual void PaintPanel(Graphics graphics,Rectangle clipRectangle) {
            this.PaintGradient(graphics,clipRectangle);
        }

        [Category("_GradientPanel")]
        [Description("Gradient Panel Properties")]
        public GradientPanelProperties Properties {
            get {
                return _properties;
            }
            set {
                _properties = value ?? new GradientPanelProperties();
            }
        }

        [Category("_GradientPanel")]
        [Description("Apply a bell-shaped distribution to the gradient?"),DefaultValue(false)]
        public bool BellShape {
            get {
                return _properties.BellShape;
            }
            set {
                _properties.BellShape = value;
            }
        }

        [Category("_GradientPanel")]
        [Description("The LinearGradientMode enumeration describing the gradient."),DefaultValue(0)]
        public LinearGradientMode GradientMode {
            get {
                return _properties.GradientMode;
            }
            set {
                _properties.GradientMode = value;
            }
        }

        [Category("_GradientPanel")]
        [Description("Starting color for the gradient"),DefaultValue(typeof(Color),"Black")]
        public Color LeftColor {
            get {
                return _properties.LeftColor;
            }
            set {
                _properties.LeftColor = value;
                base.Invalidate();
            }
        }

        [Category("_GradientPanel")]
        [DefaultValue(typeof(Color),"White"),Description("Ending color for the gradient")]
        public Color RightColor {
            get {
                return _properties.RightColor;
            }
            set {
                _properties.RightColor = value;
                base.Invalidate();
            }
        }
        [Category("_GradientPanel")]
        [Description("Apply a triangle-shaped distribution to the gradient?"),DefaultValue(false)]
        public bool TriangleShape {
            get {
                return _properties.TriangleShape;
            }
            set {
                _properties.TriangleShape = value;
            }
        }

        public class GradientPanelProperties {
            public bool BellShape { get; set; }
            public LinearGradientMode GradientMode { get; set; }
            public Color LeftColor { get; set; }
            public Color RightColor { get; set; }
            public bool TriangleShape { get; set; }
        }
    }

}