1 files changed, 105 insertions, 23 deletions
diff --git a/src/Jellyfin.Drawing.Skia/SkiaEncoder.cs b/src/Jellyfin.Drawing.Skia/SkiaEncoder.cs
index 2dac5598f..503e2f941 100644
--- a/src/Jellyfin.Drawing.Skia/SkiaEncoder.cs
+++ b/src/Jellyfin.Drawing.Skia/SkiaEncoder.cs
@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using BlurHashSharp.SkiaSharp;
 using Jellyfin.Extensions;
 using MediaBrowser.Common.Configuration;
@@ -24,6 +25,17 @@ public class SkiaEncoder : IImageEncoder
     private readonly ILogger<SkiaEncoder> _logger;
     private readonly IApplicationPaths _appPaths;
     private static readonly SKImageFilter _imageFilter;
+    private static readonly SKTypeface[] _typefaces;
+
+    /// <summary>
+    /// The default sampling options, equivalent to old high quality filter settings when upscaling.
+    /// </summary>
+    public static readonly SKSamplingOptions UpscaleSamplingOptions;
+
+    /// <summary>
+    /// The sampling options, used for downscaling images, equivalent to old high quality filter settings when not upscaling.
+    /// </summary>
+    public static readonly SKSamplingOptions DefaultSamplingOptions;
 
 #pragma warning disable CA1810
     static SkiaEncoder()
@@ -46,6 +58,26 @@ public class SkiaEncoder : IImageEncoder
             kernelOffset,
             SKShaderTileMode.Clamp,
             true);
+
+        // Initialize the list of typefaces
+        // We have to statically build a list of typefaces because MatchCharacter only accepts a single character or code point
+        // But in reality a human-readable character (grapheme cluster) could be multiple code points. For example, 🚵🏻‍♀️ is a single emoji but 5 code points (U+1F6B5 + U+1F3FB + U+200D + U+2640 + U+FE0F)
+        _typefaces =
+        [
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, '鸡'), // CJK Simplified Chinese
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, '雞'), // CJK Traditional Chinese
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, 'ノ'), // CJK Japanese
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, '각'), // CJK Korean
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, 128169), // Emojis, 128169 is the 💩emoji
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, 'ז'), // Hebrew
+            SKFontManager.Default.MatchCharacter(null, SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright, null, 'ي'), // Arabic
+            SKTypeface.FromFamilyName("sans-serif", SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright) // Default font
+        ];
+
+        // use cubic for upscaling
+        UpscaleSamplingOptions = new SKSamplingOptions(SKCubicResampler.Mitchell);
+        // use bilinear for everything else
+        DefaultSamplingOptions = new SKSamplingOptions(SKFilterMode.Linear, SKMipmapMode.Linear);
     }
 
     /// <summary>
@@ -98,6 +130,11 @@ public class SkiaEncoder : IImageEncoder
         => new HashSet<ImageFormat> { ImageFormat.Webp, ImageFormat.Jpg, ImageFormat.Png, ImageFormat.Svg };
 
     /// <summary>
+    /// Gets the default typeface to use.
+    /// </summary>
+    public static SKTypeface DefaultTypeFace => _typefaces.Last();
+
+    /// <summary>
     /// Check if the native lib is available.
     /// </summary>
     /// <returns>True if the native lib is available, otherwise false.</returns>
@@ -165,18 +202,47 @@ public class SkiaEncoder : IImageEncoder
             }
         }
 
-        using var codec = SKCodec.Create(path, out SKCodecResult result);
+        var safePath = NormalizePath(path);
+        if (new FileInfo(safePath).Length == 0)
+        {
+            _logger.LogDebug("Skip zero‑byte image {FilePath}", path);
+            return default;
+        }
+
+        using var codec = SKCodec.Create(safePath, out var result);
+
         switch (result)
         {
             case SKCodecResult.Success:
+            // Skia/SkiaSharp edge‑case: when the image header is parsed but the actual pixel
+            // decode fails (truncated JPEG/PNG, exotic ICC/EXIF, CMYK without color‑transform, etc.)
+            // `SKCodec.Create` returns a *non‑null* codec together with
+            // SKCodecResult.InternalError.  The header still contains valid dimensions,
+            // which is all we need here – so we fall back to them instead of aborting.
+            // See e.g. Skia bugs #4139, #6092.
+            case SKCodecResult.InternalError when codec is not null:
                 var info = codec.Info;
                 return new ImageDimensions(info.Width, info.Height);
+
             case SKCodecResult.Unimplemented:
                 _logger.LogDebug("Image format not supported: {FilePath}", path);
                 return default;
+
             default:
-                _logger.LogError("Unable to determine image dimensions for {FilePath}: {SkCodecResult}", path, result);
+            {
+                var boundsInfo = SKBitmap.DecodeBounds(safePath);
+
+                if (boundsInfo.Width > 0 && boundsInfo.Height > 0)
+                {
+                    return new ImageDimensions(boundsInfo.Width, boundsInfo.Height);
+                }
+
+                _logger.LogWarning(
+                    "Unable to determine image dimensions for {FilePath}: {SkCodecResult}",
+                    path,
+                    result);
                 return default;
+            }
         }
     }
 
@@ -419,7 +485,7 @@ public class SkiaEncoder : IImageEncoder
                     break;
             }
 
-            surface.DrawBitmap(bitmap, 0, 0);
+            surface.DrawBitmap(bitmap, 0, 0, DefaultSamplingOptions);
             return rotated;
         }
         catch (Exception e)
@@ -445,18 +511,23 @@ public class SkiaEncoder : IImageEncoder
     {
         using var surface = SKSurface.Create(targetInfo);
         using var canvas = surface.Canvas;
-        using var paint = new SKPaint
-        {
-            FilterQuality = SKFilterQuality.High,
-            IsAntialias = isAntialias,
-            IsDither = isDither
-        };
+        using var paint = new SKPaint();
+        paint.IsAntialias = isAntialias;
+        paint.IsDither = isDither;
+
+        // Historically, kHigh implied cubic filtering, but only when upsampling.
+        // If specified kHigh, and were down-sampling, Skia used to switch back to kMedium (bilinear filtering plus mipmaps).
+        // With current skia API, passing Mitchell cubic when down-sampling will cause serious quality degradation.
+        var samplingOptions = source.Width > targetInfo.Width || source.Height > targetInfo.Height
+            ? DefaultSamplingOptions
+            : UpscaleSamplingOptions;
 
         paint.ImageFilter = _imageFilter;
         canvas.DrawBitmap(
             source,
             SKRect.Create(0, 0, source.Width, source.Height),
             SKRect.Create(0, 0, targetInfo.Width, targetInfo.Height),
+            samplingOptions,
             paint);
 
         return surface.Snapshot();
@@ -535,20 +606,13 @@ public class SkiaEncoder : IImageEncoder
             canvas.Clear(SKColor.Parse(options.BackgroundColor));
         }
 
+        using var paint = new SKPaint();
         // Add blur if option is present
-        if (blur > 0)
-        {
-            // create image from resized bitmap to apply blur
-            using var paint = new SKPaint();
-            using var filter = SKImageFilter.CreateBlur(blur, blur);
-            paint.ImageFilter = filter;
-            canvas.DrawBitmap(resizedBitmap, SKRect.Create(width, height), paint);
-        }
-        else
-        {
-            // draw resized bitmap onto canvas
-            canvas.DrawBitmap(resizedBitmap, SKRect.Create(width, height));
-        }
+        using var filter = blur > 0 ? SKImageFilter.CreateBlur(blur, blur) : null;
+        paint.ImageFilter = filter;
+
+        // create image from resized bitmap to apply blur
+        canvas.DrawBitmap(resizedBitmap, SKRect.Create(width, height), DefaultSamplingOptions, paint);
 
         // If foreground layer present then draw
         if (hasForegroundColor)
@@ -674,7 +738,7 @@ public class SkiaEncoder : IImageEncoder
                     throw new InvalidOperationException("Image height does not match first image height.");
                 }
 
-                canvas.DrawBitmap(img, x * imgWidth, y * imgHeight.Value);
+                canvas.DrawBitmap(img, x * imgWidth, y * imgHeight.Value, DefaultSamplingOptions);
             }
         }
 
@@ -705,4 +769,22 @@ public class SkiaEncoder : IImageEncoder
             _logger.LogError(ex, "Error drawing indicator overlay");
         }
     }
+
+    /// <summary>
+    /// Return the typeface that contains the glyph for the given character.
+    /// </summary>
+    /// <param name="c">The text character.</param>
+    /// <returns>The typeface contains the character.</returns>
+    public static SKTypeface? GetFontForCharacter(string c)
+    {
+        foreach (var typeface in _typefaces)
+        {
+            if (typeface.ContainsGlyphs(c))
+            {
+                return typeface;
+            }
+        }
+
+        return null;
+    }
 }