EdgeColor.cs

using System.Diagnostics;
using System.Drawing;
 
namespace be.gaudry.model.drawing.chart
{
    /// <summary>
    ///   Structure representing edge color used for rendering.
    /// </summary>
    public struct EdgeColor
    {
 
        /// <summary>
        ///   Gets the actual color used for rendering.
        /// </summary>
        public static Color GetRenderingColor(EdgeColorType edgeColorType, Color color)
        {
            Debug.Assert(color != Color.Empty);
            if (edgeColorType == EdgeColorType.Contrast || edgeColorType == EdgeColorType.EnhancedContrast)
                edgeColorType = GetContrastColorType(color, edgeColorType);
            float correctionFactor = 0;
            switch (edgeColorType)
            {
                case EdgeColorType.SystemColor:
                    return SystemColors.WindowText;
                case EdgeColorType.SurfaceColor:
                    return color;
                case EdgeColorType.FullContrast:
                    return GetFullContrastColor(color);
                case EdgeColorType.DarkerThanSurface:
                    correctionFactor = -ColorUtil.BrightnessEnhancementFactor1;
                    break;
                case EdgeColorType.DarkerDarkerThanSurface:
                    correctionFactor = -ColorUtil.BrightnessEnhancementFactor2;
                    break;
                case EdgeColorType.LighterThanSurface:
                    correctionFactor = +ColorUtil.BrightnessEnhancementFactor1;
                    break;
                case EdgeColorType.LighterLighterThanSurface:
                    correctionFactor = +ColorUtil.BrightnessEnhancementFactor2;
                    break;
                case EdgeColorType.NoEdge:
                    return System.Drawing.Color.Transparent;
            }
            return ColorUtil.CreateColorWithCorrectedLightness(color, correctionFactor);
        }
 
        private static EdgeColorType GetContrastColorType(Color color, EdgeColorType colorType)
        {
            Debug.Assert(colorType == EdgeColorType.Contrast || colorType == EdgeColorType.EnhancedContrast);
            if (color.GetBrightness() > s_brightnessThreshold)
            {
                if (colorType == EdgeColorType.Contrast)
                    return EdgeColorType.DarkerThanSurface;
                else
                    return EdgeColorType.DarkerDarkerThanSurface;
            }
            if (colorType == EdgeColorType.Contrast)
                return EdgeColorType.LighterThanSurface;
            else
                return EdgeColorType.LighterLighterThanSurface;
        }
 
        private static Color GetFullContrastColor(Color color)
        {
            if (color.GetBrightness() > s_brightnessThreshold)
                return Color.Black;
            return Color.White;
        }
 
        private static readonly float s_brightnessThreshold = 0.4F;
    }
}