1 files changed, 186 insertions, 0 deletions
diff --git a/src/Jellyfin.Drawing.Skia/StripCollageBuilder.cs b/src/Jellyfin.Drawing.Skia/StripCollageBuilder.cs
new file mode 100644
index 000000000..c8b8f3ace
--- /dev/null
+++ b/src/Jellyfin.Drawing.Skia/StripCollageBuilder.cs
@@ -0,0 +1,186 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text.RegularExpressions;
+using SkiaSharp;
+
+namespace Jellyfin.Drawing.Skia
+{
+    /// <summary>
+    /// Used to build collages of multiple images arranged in vertical strips.
+    /// </summary>
+    public class StripCollageBuilder
+    {
+        private readonly SkiaEncoder _skiaEncoder;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StripCollageBuilder"/> class.
+        /// </summary>
+        /// <param name="skiaEncoder">The encoder to use for building collages.</param>
+        public StripCollageBuilder(SkiaEncoder skiaEncoder)
+        {
+            _skiaEncoder = skiaEncoder;
+        }
+
+        /// <summary>
+        /// Check which format an image has been encoded with using its filename extension.
+        /// </summary>
+        /// <param name="outputPath">The path to the image to get the format for.</param>
+        /// <returns>The image format.</returns>
+        public static SKEncodedImageFormat GetEncodedFormat(string outputPath)
+        {
+            ArgumentNullException.ThrowIfNull(outputPath);
+
+            var ext = Path.GetExtension(outputPath);
+
+            if (string.Equals(ext, ".jpg", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(ext, ".jpeg", StringComparison.OrdinalIgnoreCase))
+            {
+                return SKEncodedImageFormat.Jpeg;
+            }
+
+            if (string.Equals(ext, ".webp", StringComparison.OrdinalIgnoreCase))
+            {
+                return SKEncodedImageFormat.Webp;
+            }
+
+            if (string.Equals(ext, ".gif", StringComparison.OrdinalIgnoreCase))
+            {
+                return SKEncodedImageFormat.Gif;
+            }
+
+            if (string.Equals(ext, ".bmp", StringComparison.OrdinalIgnoreCase))
+            {
+                return SKEncodedImageFormat.Bmp;
+            }
+
+            // default to png
+            return SKEncodedImageFormat.Png;
+        }
+
+        /// <summary>
+        /// Create a square collage.
+        /// </summary>
+        /// <param name="paths">The paths of the images to use in the collage.</param>
+        /// <param name="outputPath">The path at which to place the resulting collage image.</param>
+        /// <param name="width">The desired width of the collage.</param>
+        /// <param name="height">The desired height of the collage.</param>
+        public void BuildSquareCollage(IReadOnlyList<string> paths, string outputPath, int width, int height)
+        {
+            using var bitmap = BuildSquareCollageBitmap(paths, width, height);
+            using var outputStream = new SKFileWStream(outputPath);
+            using var pixmap = new SKPixmap(new SKImageInfo(width, height), bitmap.GetPixels());
+            pixmap.Encode(outputStream, GetEncodedFormat(outputPath), 90);
+        }
+
+        /// <summary>
+        /// Create a thumb collage.
+        /// </summary>
+        /// <param name="paths">The paths of the images to use in the collage.</param>
+        /// <param name="outputPath">The path at which to place the resulting image.</param>
+        /// <param name="width">The desired width of the collage.</param>
+        /// <param name="height">The desired height of the collage.</param>
+        /// <param name="libraryName">The name of the library to draw on the collage.</param>
+        public void BuildThumbCollage(IReadOnlyList<string> paths, string outputPath, int width, int height, string? libraryName)
+        {
+            using var bitmap = BuildThumbCollageBitmap(paths, width, height, libraryName);
+            using var outputStream = new SKFileWStream(outputPath);
+            using var pixmap = new SKPixmap(new SKImageInfo(width, height), bitmap.GetPixels());
+            pixmap.Encode(outputStream, GetEncodedFormat(outputPath), 90);
+        }
+
+        private SKBitmap BuildThumbCollageBitmap(IReadOnlyList<string> paths, int width, int height, string? libraryName)
+        {
+            var bitmap = new SKBitmap(width, height);
+
+            using var canvas = new SKCanvas(bitmap);
+            canvas.Clear(SKColors.Black);
+
+            using var backdrop = SkiaHelper.GetNextValidImage(_skiaEncoder, paths, 0, out _);
+            if (backdrop is null)
+            {
+                return bitmap;
+            }
+
+            // resize to the same aspect as the original
+            var backdropHeight = Math.Abs(width * backdrop.Height / backdrop.Width);
+            using var residedBackdrop = SkiaEncoder.ResizeImage(backdrop, new SKImageInfo(width, backdropHeight, backdrop.ColorType, backdrop.AlphaType, backdrop.ColorSpace));
+            // draw the backdrop
+            canvas.DrawImage(residedBackdrop, 0, 0);
+
+            // draw shadow rectangle
+            using var paintColor = new SKPaint
+            {
+                Color = SKColors.Black.WithAlpha(0x78),
+                Style = SKPaintStyle.Fill
+            };
+            canvas.DrawRect(0, 0, width, height, paintColor);
+
+            var typeFace = SKTypeface.FromFamilyName("sans-serif", SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright);
+
+            // use the system fallback to find a typeface for the given CJK character
+            var nonCjkPattern = @"[^\p{IsCJKUnifiedIdeographs}\p{IsCJKUnifiedIdeographsExtensionA}\p{IsKatakana}\p{IsHiragana}\p{IsHangulSyllables}\p{IsHangulJamo}]";
+            var filteredName = Regex.Replace(libraryName ?? string.Empty, nonCjkPattern, string.Empty);
+            if (!string.IsNullOrEmpty(filteredName))
+            {
+                typeFace = SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, filteredName[0]);
+            }
+
+            // draw library name
+            using var textPaint = new SKPaint
+            {
+                Color = SKColors.White,
+                Style = SKPaintStyle.Fill,
+                TextSize = 112,
+                TextAlign = SKTextAlign.Center,
+                Typeface = typeFace,
+                IsAntialias = true
+            };
+
+            // scale down text to 90% of the width if text is larger than 95% of the width
+            var textWidth = textPaint.MeasureText(libraryName);
+            if (textWidth > width * 0.95)
+            {
+                textPaint.TextSize = 0.9f * width * textPaint.TextSize / textWidth;
+            }
+
+            canvas.DrawText(libraryName, width / 2f, (height / 2f) + (textPaint.FontMetrics.XHeight / 2), textPaint);
+
+            return bitmap;
+        }
+
+        private SKBitmap BuildSquareCollageBitmap(IReadOnlyList<string> paths, int width, int height)
+        {
+            var bitmap = new SKBitmap(width, height);
+            var imageIndex = 0;
+            var cellWidth = width / 2;
+            var cellHeight = height / 2;
+
+            using var canvas = new SKCanvas(bitmap);
+            for (var x = 0; x < 2; x++)
+            {
+                for (var y = 0; y < 2; y++)
+                {
+                    using var currentBitmap = SkiaHelper.GetNextValidImage(_skiaEncoder, paths, imageIndex, out int newIndex);
+                    imageIndex = newIndex;
+
+                    if (currentBitmap is null)
+                    {
+                        continue;
+                    }
+
+                    // Scale image. The FromBitmap creates a copy
+                    var imageInfo = new SKImageInfo(cellWidth, cellHeight, currentBitmap.ColorType, currentBitmap.AlphaType, currentBitmap.ColorSpace);
+                    using var resizedBitmap = SKBitmap.FromImage(SkiaEncoder.ResizeImage(currentBitmap, imageInfo));
+
+                    // draw this image into the strip at the next position
+                    var xPos = x * cellWidth;
+                    var yPos = y * cellHeight;
+                    canvas.DrawBitmap(resizedBitmap, xPos, yPos);
+                }
+            }
+
+            return bitmap;
+        }
+    }
+}