Merge pull request #17569 from vavallee/fix/17056-no-image-upscaling

Stop image endpoints from upscaling beyond the source resolution

2 files changed, 92 insertions, 0 deletions

diff --git a/tests/Jellyfin.Controller.Tests/Drawing/ImageHelperTests.cs b/tests/Jellyfin.Controller.Tests/Drawing/ImageHelperTests.cs
new file mode 100644
index 0000000000..571cb7f0d4
--- /dev/null
+++ b/tests/Jellyfin.Controller.Tests/Drawing/ImageHelperTests.cs
@@ -0,0 +1,64 @@
+using MediaBrowser.Controller.Drawing;
+using MediaBrowser.Model.Drawing;
+using Xunit;
+
+namespace Jellyfin.Controller.Tests.Drawing;
+
+public static class ImageHelperTests
+{
+    [Fact]
+    public static void GetNewImageSize_ExplicitSizeLargerThanSource_ClampsToSource()
+    {
+        // Regression test for https://github.com/jellyfin/jellyfin/issues/17056: the caller-supplied
+        // width/height were used verbatim, so a single request could ask for a 23100x23100 encode.
+        var options = new ImageProcessingOptions { Width = 23100, Height = 23100 };
+
+        var newSize = ImageHelper.GetNewImageSize(options, new ImageDimensions(600, 336));
+
+        Assert.Equal(336, newSize.Width);
+        Assert.Equal(336, newSize.Height);
+    }
+
+    [Fact]
+    public static void GetNewImageSize_WidthLargerThanSource_ClampsToSource()
+    {
+        var options = new ImageProcessingOptions { Width = 10000 };
+
+        var newSize = ImageHelper.GetNewImageSize(options, new ImageDimensions(600, 336));
+
+        Assert.Equal(600, newSize.Width);
+        Assert.Equal(336, newSize.Height);
+    }
+
+    [Fact]
+    public static void GetNewImageSize_FillLargerThanSource_ClampsToSource()
+    {
+        // ResizeFill already refused to upscale; this pins that behaviour.
+        var options = new ImageProcessingOptions { FillWidth = 23100, FillHeight = 23100 };
+
+        var newSize = ImageHelper.GetNewImageSize(options, new ImageDimensions(600, 336));
+
+        Assert.Equal(600, newSize.Width);
+        Assert.Equal(336, newSize.Height);
+    }
+
+    [Fact]
+    public static void GetNewImageSize_SmallerThanSource_StillDownscales()
+    {
+        var options = new ImageProcessingOptions { MaxWidth = 300 };
+
+        var newSize = ImageHelper.GetNewImageSize(options, new ImageDimensions(600, 336));
+
+        Assert.Equal(300, newSize.Width);
+        Assert.Equal(168, newSize.Height);
+    }
+
+    [Fact]
+    public static void GetNewImageSize_NoSizeRequested_ReturnsSource()
+    {
+        var newSize = ImageHelper.GetNewImageSize(new ImageProcessingOptions(), new ImageDimensions(600, 336));
+
+        Assert.Equal(600, newSize.Width);
+        Assert.Equal(336, newSize.Height);
+    }
+}
diff --git a/tests/Jellyfin.Model.Tests/Drawing/DrawingUtilsTests.cs b/tests/Jellyfin.Model.Tests/Drawing/DrawingUtilsTests.cs
new file mode 100644
index 0000000000..473b07a8a1
--- /dev/null
+++ b/tests/Jellyfin.Model.Tests/Drawing/DrawingUtilsTests.cs
@@ -0,0 +1,28 @@
+using MediaBrowser.Model.Drawing;
+using Xunit;
+
+namespace Jellyfin.Model.Drawing;
+
+public static class DrawingUtilsTests
+{
+    [Theory]
+    // Already inside the box, returned untouched.
+    [InlineData(600, 336, 1920, 1080, 600, 336)]
+    [InlineData(1920, 1080, 1920, 1080, 1920, 1080)]
+    // Scaled down uniformly, requested aspect ratio preserved.
+    [InlineData(23100, 23100, 1920, 1080, 1080, 1080)]
+    [InlineData(3840, 2160, 1920, 1080, 1920, 1080)]
+    [InlineData(1200, 400, 600, 336, 600, 200)]
+    // Extreme ratios still produce at least one pixel per axis.
+    [InlineData(10000, 1, 100, 100, 100, 1)]
+    // Degenerate inputs are passed through rather than dividing by zero.
+    [InlineData(600, 336, 0, 0, 600, 336)]
+    [InlineData(0, 0, 1920, 1080, 0, 0)]
+    public static void ScaleDownToFit_Bounds_WithoutUpscaling(int width, int height, int boxWidth, int boxHeight, int expectedWidth, int expectedHeight)
+    {
+        var scaled = DrawingUtils.ScaleDownToFit(new ImageDimensions(width, height), new ImageDimensions(boxWidth, boxHeight));
+
+        Assert.Equal(expectedWidth, scaled.Width);
+        Assert.Equal(expectedHeight, scaled.Height);
+    }
+}