ImageSharp/tests/ImageSharp.Tests/Drawing/BeziersTests.cs

// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System.Numerics;

using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.Processing.Drawing;
using SixLabors.ImageSharp.Processing.Overlays;
using SixLabors.Memory;
using Xunit;

namespace SixLabors.ImageSharp.Tests.Drawing
{
    public class Beziers : FileTestBase
    {
        [Fact]
        public void ImageShouldBeOverlayedByBezierLine()
        {
            string path = TestEnvironment.CreateOutputDirectory("Drawing", "BezierLine");
            using (var image = new Image<Rgba32>(500, 500))
            {
                image.Mutate(
                    x => x.BackgroundColor(Rgba32.Blue).DrawBeziers(
                        Rgba32.HotPink,
                        5,
                        new SixLabors.Primitives.PointF[]
                            {
                                new Vector2(10, 400), new Vector2(30, 10), new Vector2(240, 30), new Vector2(300, 400)
                            }));
                image.Save($"{path}/Simple.png");

                Buffer2D<Rgba32> sourcePixels = image.GetRootFramePixelBuffer();
                //top of curve
                Assert.Equal(Rgba32.HotPink, sourcePixels[138, 115]);

                //start points
                Assert.Equal(Rgba32.HotPink, sourcePixels[10, 395]);
                Assert.Equal(Rgba32.HotPink, sourcePixels[300, 395]);

                //curve points should not be never be set
                Assert.Equal(Rgba32.Blue, sourcePixels[30, 10]);
                Assert.Equal(Rgba32.Blue, sourcePixels[240, 30]);

                // inside shape should be empty
                Assert.Equal(Rgba32.Blue, sourcePixels[200, 250]);
            }
        }


        [Fact]
        public void ImageShouldBeOverlayedBezierLineWithOpacity()
        {
            string path = TestEnvironment.CreateOutputDirectory("Drawing", "BezierLine");

            var color = new Rgba32(Rgba32.HotPink.R, Rgba32.HotPink.G, Rgba32.HotPink.B, 150);

            using (var image = new Image<Rgba32>(500, 500))
            {
                image.Mutate(
                    x => x.BackgroundColor(Rgba32.Blue).DrawBeziers(
                        color,
                        10,
                        new SixLabors.Primitives.PointF[]
                            {
                                new Vector2(10, 400), new Vector2(30, 10), new Vector2(240, 30), new Vector2(300, 400)
                            }));
                image.Save($"{path}/Opacity.png");

                //shift background color towards foreground color by the opacity amount
                var mergedColor = new Rgba32(
                    Vector4.Lerp(Rgba32.Blue.ToVector4(), Rgba32.HotPink.ToVector4(), 150f / 255f));

                Buffer2D<Rgba32> sourcePixels = image.GetRootFramePixelBuffer();
                // top of curve
                Assert.Equal(mergedColor, sourcePixels[138, 115]);

                // start points
                Assert.Equal(mergedColor, sourcePixels[10, 395]);
                Assert.Equal(mergedColor, sourcePixels[300, 395]);

                // curve points should not be never be set
                Assert.Equal(Rgba32.Blue, sourcePixels[30, 10]);
                Assert.Equal(Rgba32.Blue, sourcePixels[240, 30]);

                // inside shape should be empty
                Assert.Equal(Rgba32.Blue, sourcePixels[200, 250]);
            }
        }
    }
}