ImageSharp/tests/ImageSharp.Tests/Drawing/SolidBezierTests.cs

// <copyright file="ColorConversionTests.cs" company="James Jackson-South">
// Copyright (c) James Jackson-South and contributors.
// Licensed under the Apache License, Version 2.0.
// </copyright>

namespace ImageSharp.Tests.Drawing
{
    using Drawing;
    using ImageSharp.Drawing;
    using ImageSharp.Drawing.Shapes;
    using System;
    using System.Diagnostics.CodeAnalysis;
    using System.IO;
    using System.Numerics;
    using Xunit;

    public class SolidBezierTests : FileTestBase
    {
        [Fact]
        public void ImageShouldBeOverlayedByFilledPolygon()
        {
            string path = CreateOutputDirectory("Drawing", "FilledBezier");
            var simplePath = new[] {
                        new Vector2(10, 400),
                        new Vector2(30, 10),
                        new Vector2(240, 30),
                        new Vector2(300, 400)
            };
            var image = new Image(500, 500);

            using (FileStream output = File.OpenWrite($"{path}/Simple.png"))
            {
                image
                    .BackgroundColor(Color.Blue)
                    .Fill(Color.HotPink,new BezierPolygon(simplePath))
                    .Save(output);
            }

            using (var sourcePixels = image.Lock())
            {
                //top of curve
                Assert.Equal(Color.HotPink, sourcePixels[138, 116]);

                //start points                
                Assert.Equal(Color.HotPink, sourcePixels[10, 400]);
                Assert.Equal(Color.HotPink, sourcePixels[300, 400]);

                //curve points should not be never be set
                Assert.Equal(Color.Blue, sourcePixels[30, 10]);
                Assert.Equal(Color.Blue, sourcePixels[240, 30]);

                // inside shape should not be empty
                Assert.Equal(Color.HotPink, sourcePixels[200, 250]);
            }
        }

        [Fact]
        public void ImageShouldBeOverlayedByFilledPolygonOpacity()
        {
            string path = CreateOutputDirectory("Drawing", "FilledBezier");
            var simplePath = new[] {
                        new Vector2(10, 400),
                        new Vector2(30, 10),
                        new Vector2(240, 30),
                        new Vector2(300, 400)
            };
            var color = new Color(Color.HotPink.R, Color.HotPink.G, Color.HotPink.B, 150);

            var image = new Image(500, 500);

            using (FileStream output = File.OpenWrite($"{path}/Opacity.png"))
            {
                image
                    .BackgroundColor(Color.Blue)
                    .Fill(color, new BezierPolygon(simplePath))
                    .Save(output);
            }

            //shift background color towards forground color by the opacity amount
            var mergedColor = new Color(Vector4.Lerp(Color.Blue.ToVector4(), Color.HotPink.ToVector4(), 150f / 255f));

            using (var sourcePixels = image.Lock())
            {
                //top of curve
                Assert.Equal(mergedColor, sourcePixels[138, 116]);

                //start points                
                Assert.Equal(mergedColor, sourcePixels[10, 400]);
                Assert.Equal(mergedColor, sourcePixels[300, 400]);

                //curve points should not be never be set
                Assert.Equal(Color.Blue, sourcePixels[30, 10]);
                Assert.Equal(Color.Blue, sourcePixels[240, 30]);

                // inside shape should not be empty
                Assert.Equal(mergedColor, sourcePixels[200, 250]);
            }
        }
        
    }
}