/*
 * NPlot - A charting library for .NET
 * 
 * LinearGradient.cs
 * Copyright (C) 2003-2006 Matt Howlett and others.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of NPlot nor the names of its contributors may
 *    be used to endorse or promote products derived from this software without
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Drawing;

namespace NPlot
{
    /// <summary>
    /// Class for creating a linear gradient.
    /// </summary>
    public class LinearGradient : IGradient
    {
        private Color voidColor_ = Color.Black;

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="minColor">The color corresponding to 0.0</param>
        /// <param name="maxColor">The color corresponding to 1.0</param>
        public LinearGradient(Color minColor, Color maxColor)
        {
            MinColor = minColor;
            MaxColor = maxColor;
        }

        /// <summary>
        /// The color corresponding to 0.0
        /// </summary>
        public Color MaxColor { get; set; }

        /// <summary>
        /// The color corresponding to 1.0
        /// </summary>
        public Color MinColor { get; set; }

        /// <summary>
        /// The color corresponding to NaN
        /// </summary>
        public Color VoidColor
        {
            get { return voidColor_; }
            set { voidColor_ = value; }
        }

        /// <summary>
        /// Gets a color corresponding to a number between 0.0 and 1.0 inclusive. The color will
        /// be a linear interpolation of the min and max colors.
        /// </summary>
        /// <param name="prop">the number to get corresponding color for (between 0.0 and 1.0)</param>
        /// <returns>The color corresponding to the supplied number.</returns>
        public Color GetColor(double prop)
        {
            if (Double.IsNaN(prop))
            {
                return voidColor_;
            }

            if (prop <= 0.0)
            {
                return MinColor;
            }

            if (prop >= 1.0)
            {
                return MaxColor;
            }

            byte r = (byte) ((MinColor.R) + (int) ((MaxColor.R - (double) MinColor.R)*prop));
            byte g = (byte) ((MinColor.G) + (int) ((MaxColor.G - (double) MinColor.G)*prop));
            byte b = (byte) ((MinColor.B) + (int) ((MaxColor.B - (double) MinColor.B)*prop));

            return Color.FromArgb(r, g, b);
        }
    }
}