1 files changed, 147 insertions, 0 deletions
diff --git a/src/Jellyfin.Drawing.Skia/SplashscreenBuilder.cs b/src/Jellyfin.Drawing.Skia/SplashscreenBuilder.cs
new file mode 100644
index 000000000..990556623
--- /dev/null
+++ b/src/Jellyfin.Drawing.Skia/SplashscreenBuilder.cs
@@ -0,0 +1,147 @@
+using System;
+using System.Collections.Generic;
+using SkiaSharp;
+
+namespace Jellyfin.Drawing.Skia;
+
+/// <summary>
+/// Used to build the splashscreen.
+/// </summary>
+public class SplashscreenBuilder
+{
+    private const int FinalWidth = 1920;
+    private const int FinalHeight = 1080;
+    // generated collage resolution should be higher than the final resolution
+    private const int WallWidth = FinalWidth * 3;
+    private const int WallHeight = FinalHeight * 2;
+    private const int Rows = 6;
+    private const int Spacing = 20;
+
+    private readonly SkiaEncoder _skiaEncoder;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SplashscreenBuilder"/> class.
+    /// </summary>
+    /// <param name="skiaEncoder">The SkiaEncoder.</param>
+    public SplashscreenBuilder(SkiaEncoder skiaEncoder)
+    {
+        _skiaEncoder = skiaEncoder;
+    }
+
+    /// <summary>
+    /// Generate a splashscreen.
+    /// </summary>
+    /// <param name="posters">The poster paths.</param>
+    /// <param name="backdrops">The landscape paths.</param>
+    /// <param name="outputPath">The output path.</param>
+    public void GenerateSplash(IReadOnlyList<string> posters, IReadOnlyList<string> backdrops, string outputPath)
+    {
+        using var wall = GenerateCollage(posters, backdrops);
+        using var transformed = Transform3D(wall);
+
+        using var outputStream = new SKFileWStream(outputPath);
+        using var pixmap = new SKPixmap(new SKImageInfo(FinalWidth, FinalHeight), transformed.GetPixels());
+        pixmap.Encode(outputStream, StripCollageBuilder.GetEncodedFormat(outputPath), 90);
+    }
+
+    /// <summary>
+    /// Generates a collage of posters and landscape pictures.
+    /// </summary>
+    /// <param name="posters">The poster paths.</param>
+    /// <param name="backdrops">The landscape paths.</param>
+    /// <returns>The created collage as a bitmap.</returns>
+    private SKBitmap GenerateCollage(IReadOnlyList<string> posters, IReadOnlyList<string> backdrops)
+    {
+        var posterIndex = 0;
+        var backdropIndex = 0;
+
+        var bitmap = new SKBitmap(WallWidth, WallHeight);
+        using var canvas = new SKCanvas(bitmap);
+        canvas.Clear(SKColors.Black);
+
+        int posterHeight = WallHeight / 6;
+
+        for (int i = 0; i < Rows; i++)
+        {
+            int imageCounter = Random.Shared.Next(0, 5);
+            int currentWidthPos = i * 75;
+            int currentHeight = i * (posterHeight + Spacing);
+
+            while (currentWidthPos < WallWidth)
+            {
+                SKBitmap? currentImage;
+
+                switch (imageCounter)
+                {
+                    case 0:
+                    case 2:
+                    case 3:
+                        currentImage = SkiaHelper.GetNextValidImage(_skiaEncoder, posters, posterIndex, out int newPosterIndex);
+                        posterIndex = newPosterIndex;
+                        break;
+                    default:
+                        currentImage = SkiaHelper.GetNextValidImage(_skiaEncoder, backdrops, backdropIndex, out int newBackdropIndex);
+                        backdropIndex = newBackdropIndex;
+                        break;
+                }
+
+                if (currentImage is null)
+                {
+                    throw new ArgumentException("Not enough valid pictures provided to create a splashscreen!");
+                }
+
+                // resize to the same aspect as the original
+                var imageWidth = Math.Abs(posterHeight * currentImage.Width / currentImage.Height);
+                using var resizedBitmap = new SKBitmap(imageWidth, posterHeight);
+                currentImage.ScalePixels(resizedBitmap, SKFilterQuality.High);
+
+                // draw on canvas
+                canvas.DrawBitmap(resizedBitmap, currentWidthPos, currentHeight);
+
+                currentWidthPos += imageWidth + Spacing;
+
+                currentImage.Dispose();
+
+                if (imageCounter >= 4)
+                {
+                    imageCounter = 0;
+                }
+                else
+                {
+                    imageCounter++;
+                }
+            }
+        }
+
+        return bitmap;
+    }
+
+    /// <summary>
+    /// Transform the collage in 3D space.
+    /// </summary>
+    /// <param name="input">The bitmap to transform.</param>
+    /// <returns>The transformed image.</returns>
+    private SKBitmap Transform3D(SKBitmap input)
+    {
+        var bitmap = new SKBitmap(FinalWidth, FinalHeight);
+        using var canvas = new SKCanvas(bitmap);
+        canvas.Clear(SKColors.Black);
+        var matrix = new SKMatrix
+        {
+            ScaleX = 0.324108899f,
+            ScaleY = 0.563934922f,
+            SkewX = -0.244337708f,
+            SkewY = 0.0377609022f,
+            TransX = 42.0407715f,
+            TransY = -198.104706f,
+            Persp0 = -9.08959337E-05f,
+            Persp1 = 6.85242048E-05f,
+            Persp2 = 0.988209724f
+        };
+
+        canvas.SetMatrix(matrix);
+        canvas.DrawBitmap(input, 0, 0);
+
+        return bitmap;
+    }
+}