Blend.cs

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using SkiaSharp;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Graphs.Functions.Colors
{
    public class Blend : FunctionMultiVariate
    {
        public Blend(ScriptNode c1, ScriptNode c2, ScriptNode p, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { c1, c2, p }, FunctionMultiVariate.argumentTypes3Scalar, Start, Length, Expression)
        {
        }
 
        public override string[] DefaultArgumentNames
        {
            get
            {
                return new string[] { "c1", "c2", "p" };
            }
        }
 
        public override string FunctionName
        {
            get
            {
                return "Blend";
            }
        }
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            object x1 = Arguments[0].AssociatedObjectValue;
            object x2 = Arguments[1].AssociatedObjectValue;
            double p = Expression.ToDouble(Arguments[2].AssociatedObjectValue);
            PixelInformation Img1, Img2;
            SKColor c1, c2;
 
            if (x1 is SKColor C1)
            {
                c1 = C1;
                Img1 = null;
            }
            else if (x1 is Graph G1)
            {
                Img1 = G1.CreatePixels(Variables);
                c1 = SKColor.Empty;
            }
            else if (x1 is SKImage I1)
            {
                Img1 = PixelInformation.FromImage(I1);
                c1 = SKColor.Empty;
            }
            else
            {
                Img1 = null;
                c1 = Graph.ToColor(x1);
            }
 
            if (x2 is SKColor C2)
            {
                c2 = C2;
                Img2 = null;
            }
            else if (x2 is Graph G2)
            {
                Img2 = G2.CreatePixels(Variables);
                c2 = SKColor.Empty;
            }
            else if (x2 is SKImage I2)
            {
                Img2 = PixelInformation.FromImage(I2);
                c2 = SKColor.Empty;
            }
            else
            {
                Img2 = null;
                c2 = Graph.ToColor(x2);
            }
 
            if (Img1 is null && Img2 is null)
                return new ObjectValue(BlendColors(c1, c2, p));
            else if (Img1 is null)
                return new GraphBitmap(Variables, BlendColors(Img2, c1, 1 - p));
            else if (Img2 is null)
                return new GraphBitmap(Variables, BlendColors(Img1, c2, p));
            else
                return new GraphBitmap(Variables, BlendColors(Img1, Img2, p));
        }
 
        public static SKColor BlendColors(SKColor c1, SKColor c2, double p)
        {
            int R = (int)(c1.Red * (1 - p) + c2.Red * p + 0.5);
            int G = (int)(c1.Green * (1 - p) + c2.Green * p + 0.5);
            int B = (int)(c1.Blue * (1 - p) + c2.Blue * p + 0.5);
            int A = (int)(c1.Alpha * (1 - p) + c2.Alpha * p + 0.5);
 
            if (R < 0)
                R = 0;
            else if (R > 255)
                R = 255;
 
            if (G < 0)
                G = 0;
            else if (G > 255)
                G = 255;
 
            if (B < 0)
                B = 0;
            else if (B > 255)
                B = 255;
 
            if (A < 0)
                A = 0;
            else if (A > 255)
                A = 255;
 
            return new SKColor((byte)R, (byte)G, (byte)B, (byte)A);
        }
 
        public static PixelInformation BlendColors(PixelInformation Pixels, SKColor Color, double p)
        {
            PixelInformationRaw Raw = Pixels.GetRaw();
            byte[] Bin = (byte[])Raw.Binary.Clone();
            int i, j, c = Raw.Binary.Length;
            byte R = Color.Red;
            byte G = Color.Green;
            byte B = Color.Blue;
            byte A = Color.Alpha;
 
            for (i = 0; i < c; i++)
            {
                j = (int)(Bin[i] * (1 - p) + B * p + 0.5);
                if (j < 0)
                    Bin[i] = 0;
                else if (j > 255)
                    Bin[i] = 255;
                else
                    Bin[i] = (byte)j;
 
                j = (int)(Bin[++i] * (1 - p) + G * p + 0.5);
                if (j < 0)
                    Bin[i] = 0;
                else if (j > 255)
                    Bin[i] = 255;
                else
                    Bin[i] = (byte)j;
 
                j = (int)(Bin[++i] * (1 - p) + R * p + 0.5);
                if (j < 0)
                    Bin[i] = 0;
                else if (j > 255)
                    Bin[i] = 255;
                else
                    Bin[i] = (byte)j;
 
                j = (int)(Bin[++i] * (1 - p) + A * p + 0.5);
                if (j < 0)
                    Bin[i] = 0;
                else if (j > 255)
                    Bin[i] = 255;
                else
                    Bin[i] = (byte)j;
            }
 
            return new PixelInformationRaw(Raw.ColorType, Bin, Raw.Width, Raw.Height, Raw.BytesPerRow);
        }
 
        public static PixelInformation BlendColors(PixelInformation Image1, PixelInformation Image2, double p)
        {
            if (Image1.Width != Image2.Width || Image1.Height != Image2.Height)
                throw new ArgumentException("Images not of the same size.", nameof(Image2));
 
            PixelInformationRaw Raw1 = Image1.GetRaw();
            PixelInformationRaw Raw2 = Image2.GetRaw();
            byte[] Bin1 = (byte[])Raw1.Binary.Clone();
            byte[] Bin2 = Raw2.Binary;
            int i, j, c = Bin1.Length;
 
            if (Bin2.Length != c)
                throw new ArgumentException("Images not of the same size.", nameof(Image2));
 
            for (i = 0; i < c; i++)
            {
                j = (int)(Bin1[i] * (1 - p) + Bin2[i] * p + 0.5);
                if (j < 0)
                    Bin1[i] = 0;
                else if (j > 255)
                    Bin1[i] = 255;
                else
                    Bin1[i] = (byte)j;
            }
 
            return new PixelInformationRaw(Raw1.ColorType, Bin1, Raw1.Width, Raw1.Height, Raw1.BytesPerRow);
        }
 
    }
}