LIBMAS/PluginAssemblys/ColorsFormPlugin/ColorWheel.cs

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Windows.Forms;

namespace PaintDotNet
{
    internal class ColorWheel : UserControl
    {
        /// <summary> 
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;
        private Bitmap renderBitmap = null;
        private bool tracking = false;
        private Point lastMouseXY;

        // this number controls what you might call the tesselation of the color wheel. higher #'s = slower, lower #'s = looks worse
        private const int colorTesselation = 60;

        private PictureBox wheelPictureBox;

        private HsvColor hsvColor;
        public HsvColor HsvColor
        {
            get
            {
                return hsvColor;
            }

            set
            {
                if (hsvColor != value)
                {
                    HsvColor oldColor = hsvColor;
                    hsvColor = value;
                    this.OnColorChanged();
                    Refresh();
                }
            }
        }

        public ColorWheel()
        {
            // This call is required by the Windows.Forms Form Designer.
            InitializeComponent();

            //wheelRegion = new PdnRegion();
            hsvColor = new HsvColor(0, 0, 0);
        }

        private static PointF SphericalToCartesian(float r, float theta)
        {
            float x;
            float y;

            x = r * (float)Math.Cos(theta);
            y = r * (float)Math.Sin(theta);

            return new PointF(x, y);
        }

        private static PointF[] GetCirclePoints(float r, PointF center)
        {
            PointF[] points = new PointF[colorTesselation];

            for (int i = 0; i < colorTesselation; i++)
            {
                float theta = ((float)i / (float)colorTesselation) * 2 * (float)Math.PI;
                points[i] = SphericalToCartesian(r, theta);
                points[i].X += center.X;
                points[i].Y += center.Y;
            }

            return points;
        }

        private Color[] GetColors()
        {
            Color[] colors = new Color[colorTesselation];

            for (int i = 0; i < colorTesselation; i++)
            {
                int hue = (i * 360) / colorTesselation;
                colors[i] = new HsvColor(hue, 100, 100).ToColor();
            }

            return colors;
        }

        protected override void OnLoad(EventArgs e)
        {
            InitRendering();
            base.OnLoad(e);
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            InitRendering();
            base.OnPaint(e);
        }

        private void InitRendering()
        {
            if (this.renderBitmap == null)
            {
                InitRenderSurface();
                this.wheelPictureBox.SizeMode = PictureBoxSizeMode.StretchImage;
                int size = (int)Math.Ceiling(ComputeDiameter(this.Size));
                this.wheelPictureBox.Size = new Size(size, size);
                this.wheelPictureBox.Image = this.renderBitmap;
            }
        }

        private void WheelPictureBox_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
        {
            float radius = ComputeRadius(Size);
            float theta = ((float)HsvColor.Hue / 360.0f) * 2.0f * (float)Math.PI;
            float alpha = ((float)HsvColor.Saturation / 100.0f);
            float x = (alpha * (radius - 1) * (float)Math.Cos(theta)) + radius;
            float y = (alpha * (radius - 1) * (float)Math.Sin(theta)) + radius;
            int ix = (int)x;
            int iy = (int)y;

            // Draw the 'target rectangle'
            GraphicsContainer container = e.Graphics.BeginContainer();
            e.Graphics.PixelOffsetMode = PixelOffsetMode.None;
            e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
            e.Graphics.DrawRectangle(Pens.Black, ix - 1, iy - 1, 3, 3);
            e.Graphics.DrawRectangle(Pens.White, ix, iy, 1, 1);
            e.Graphics.EndContainer(container);
        }

        private void InitRenderSurface()
        {
            if (renderBitmap != null)
            {
                renderBitmap.Dispose();
            }

            int wheelDiameter = (int)ComputeDiameter(Size);

            renderBitmap = new Bitmap(Math.Max(1, (wheelDiameter * 4) / 3),
                                      Math.Max(1, (wheelDiameter * 4) / 3), PixelFormat.Format24bppRgb);

            using (Graphics g1 = Graphics.FromImage(renderBitmap))
            {
                g1.Clear(this.BackColor);
                DrawWheel(g1, renderBitmap.Width, renderBitmap.Height);
            }
        }

        private void DrawWheel(Graphics g, int width, int height)
        {
            float radius = ComputeRadius(new Size(width, height));
            PointF[] points = GetCirclePoints(Math.Max(1.0f, (float)radius - 1), new PointF(radius, radius));

            using (PathGradientBrush pgb = new PathGradientBrush(points))
            {
                pgb.CenterColor = new HsvColor(0, 0, 100).ToColor();
                pgb.CenterPoint = new PointF(radius, radius);
                pgb.SurroundColors = GetColors();

                g.FillEllipse(pgb, 0, 0, radius * 2, radius * 2);
            }
        }

        private static float ComputeRadius(Size size)
        {
            return Math.Min((float)size.Width / 2, (float)size.Height / 2);
        }

        private static float ComputeDiameter(Size size)
        {
            return Math.Min((float)size.Width, (float)size.Height);
        }

        protected override void OnResize(EventArgs e)
        {
            base.OnResize(e);

            if (renderBitmap != null && (ComputeRadius(Size) != ComputeRadius(renderBitmap.Size)))
            {
                renderBitmap.Dispose();
                renderBitmap = null;
            }

            Invalidate();
        }

        public event EventHandler ColorChanged;
        protected virtual void OnColorChanged()
        {
            if (ColorChanged != null)
            {
                ColorChanged(this, EventArgs.Empty);
            }
        }

        private void GrabColor(Point mouseXY)
        {
            // center our coordinate system so the middle is (0,0), and positive Y is facing up
            int cx = mouseXY.X - (Width / 2);
            int cy = mouseXY.Y - (Height / 2);

            double theta = Math.Atan2(cy, cx);

            if (theta < 0)
            {
                theta += 2 * Math.PI;
            }

            double alpha = Math.Sqrt((cx * cx) + (cy * cy));

            int h = (int)((theta / (Math.PI * 2)) * 360.0);
            int s = (int)Math.Min(100.0, (alpha / (double)(Width / 2)) * 100);
            int v = 100;

            hsvColor = new HsvColor(h, s, v);
            OnColorChanged();
            Invalidate(true);
        }

        protected override void OnMouseDown(MouseEventArgs e)
        {
            base.OnMouseDown(e);

            if (e.Button == MouseButtons.Left)
            {
                tracking = true;
            }
        }

        protected override void OnMouseUp(MouseEventArgs e)
        {
            base.OnMouseUp(e);

            if (tracking)
            {
                GrabColor(new Point(e.X, e.Y));
            }

            tracking = false;
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);

            lastMouseXY = new Point(e.X, e.Y);

            if (tracking)
            {
                GrabColor(new Point(e.X, e.Y));
            }
        }

        /// <summary> 
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (components != null)
                {
                    components.Dispose();
                    components = null;
                }
            }

            base.Dispose(disposing);
        }

        #region Component Designer generated code
        /// <summary> 
        /// Required method for Designer support - do not modify 
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.wheelPictureBox = new System.Windows.Forms.PictureBox();
            this.SuspendLayout();
            // 
            // wheelPictureBox
            // 
            this.wheelPictureBox.Location = new System.Drawing.Point(0, 0);
            this.wheelPictureBox.Name = "wheelPictureBox";
            this.wheelPictureBox.TabIndex = 0;
            this.wheelPictureBox.TabStop = false;
            this.wheelPictureBox.Click += new System.EventHandler(this.wheelPictureBox_Click);
            this.wheelPictureBox.Paint += new System.Windows.Forms.PaintEventHandler(this.WheelPictureBox_Paint);
            this.wheelPictureBox.MouseUp += new System.Windows.Forms.MouseEventHandler(this.wheelPictureBox_MouseUp);
            this.wheelPictureBox.MouseMove += new System.Windows.Forms.MouseEventHandler(this.wheelPictureBox_MouseMove);
            this.wheelPictureBox.MouseDown += new System.Windows.Forms.MouseEventHandler(this.wheelPictureBox_MouseDown);
            // 
            // ColorWheel
            // 
            this.Controls.Add(this.wheelPictureBox);
            this.Name = "ColorWheel";
            this.ResumeLayout(false);

        }
        #endregion

        private void wheelPictureBox_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            OnMouseMove(e);
        }

        private void wheelPictureBox_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            OnMouseUp(e);
        }

        private void wheelPictureBox_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            OnMouseDown(e);
        }

        private void wheelPictureBox_Click(object sender, System.EventArgs e)
        {
            OnClick(e);
        }
    }
}