Only compare a subset of frames.

Author: JimBobSquarePants

tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs

@@ -40,9 +40,12 @@ public void Decode_VerifyAllFrames<TPixel>(TestImageProvider<TPixel> provider)
     public void Decode_Issue2450<TPixel>(TestImageProvider<TPixel> provider)
     where TPixel : unmanaged, IPixel<TPixel>
     {
+        // Images have many frames, only compare a selection of them.
+        static bool Predicate(int i, int _) => i % 8 == 0;
+
         using Image<TPixel> image = provider.GetImage();
-        image.DebugSaveMultiFrame(provider);
-        image.CompareToReferenceOutputMultiFrame(provider, ImageComparer.Exact);
+        image.DebugSaveMultiFrame(provider, predicate: Predicate);
+        image.CompareToReferenceOutputMultiFrame(provider, ImageComparer.Exact, predicate: Predicate);
     }
 
     [Theory]

tests/ImageSharp.Tests/TestUtilities/ImageComparison/ImageComparer.cs

@@ -46,19 +46,38 @@ public static ImageSimilarityReport<TPixelA, TPixelB> CompareImagesOrFrames<TPix
     public static IEnumerable<ImageSimilarityReport<TPixelA, TPixelB>> CompareImages<TPixelA, TPixelB>(
         this ImageComparer comparer,
         Image<TPixelA> expected,
-        Image<TPixelB> actual)
+        Image<TPixelB> actual,
+        Func<int, int, bool> predicate = null)
         where TPixelA : unmanaged, IPixel<TPixelA>
         where TPixelB : unmanaged, IPixel<TPixelB>
     {
-        var result = new List<ImageSimilarityReport<TPixelA, TPixelB>>();
+        List<ImageSimilarityReport<TPixelA, TPixelB>> result = new();
 
-        if (expected.Frames.Count != actual.Frames.Count)
+        int expectedFrameCount = actual.Frames.Count;
+        if (predicate != null)
+        {
+            expectedFrameCount = 0;
+            for (int i = 0; i < actual.Frames.Count; i++)
+            {
+                if (predicate(i, actual.Frames.Count))
+                {
+                    expectedFrameCount++;
+                }
+            }
+        }
+
+        if (expected.Frames.Count != expectedFrameCount)
         {
-            throw new Exception("Frame count does not match!");
+            throw new ImagesSimilarityException("Frame count does not match!");
         }
 
         for (int i = 0; i < expected.Frames.Count; i++)
         {
+            if (predicate != null && !predicate(i, expected.Frames.Count))
+            {
+                continue;
+            }
+
             ImageSimilarityReport<TPixelA, TPixelB> report = comparer.CompareImagesOrFrames(i, expected.Frames[i], actual.Frames[i]);
             if (!report.IsEmpty)
             {
@@ -72,7 +91,8 @@ public static IEnumerable<ImageSimilarityReport<TPixelA, TPixelB>> CompareImages
     public static void VerifySimilarity<TPixelA, TPixelB>(
         this ImageComparer comparer,
         Image<TPixelA> expected,
-        Image<TPixelB> actual)
+        Image<TPixelB> actual,
+        Func<int, int, bool> predicate = null)
         where TPixelA : unmanaged, IPixel<TPixelA>
         where TPixelB : unmanaged, IPixel<TPixelB>
     {
@@ -81,12 +101,25 @@ public static void VerifySimilarity<TPixelA, TPixelB>(
             throw new ImageDimensionsMismatchException(expected.Size, actual.Size);
         }
 
-        if (expected.Frames.Count != actual.Frames.Count)
+        int expectedFrameCount = actual.Frames.Count;
+        if (predicate != null)
+        {
+            expectedFrameCount = 0;
+            for (int i = 0; i < actual.Frames.Count; i++)
+            {
+                if (predicate(i, actual.Frames.Count))
+                {
+                    expectedFrameCount++;
+                }
+            }
+        }
+
+        if (expected.Frames.Count != expectedFrameCount)
         {
             throw new ImagesSimilarityException("Image frame count does not match!");
         }
 
-        IEnumerable<ImageSimilarityReport> reports = comparer.CompareImages(expected, actual);
+        IEnumerable<ImageSimilarityReport> reports = comparer.CompareImages(expected, actual, predicate);
         if (reports.Any())
         {
             throw new ImageDifferenceIsOverThresholdException(reports);

tests/ImageSharp.Tests/TestUtilities/ImagingTestCaseUtility.cs

@@ -184,7 +184,8 @@ public IEnumerable<string> GetTestOutputFileNamesMultiFrame(
         string extension = null,
         object testOutputDetails = null,
         bool appendPixelTypeToFileName = true,
-        bool appendSourceFileOrDescription = true)
+        bool appendSourceFileOrDescription = true,
+        Func<int, int, bool> predicate = null)
     {
         string baseDir = this.GetTestOutputFileName(string.Empty, testOutputDetails, appendPixelTypeToFileName, appendSourceFileOrDescription);
 
@@ -195,8 +196,12 @@ public IEnumerable<string> GetTestOutputFileNamesMultiFrame(
 
         for (int i = 0; i < frameCount; i++)
         {
-            string filePath = $"{baseDir}/{i:D2}.{extension}";
-            yield return filePath;
+            if (predicate != null && !predicate(i, frameCount))
+            {
+                continue;
+            }
+
+            yield return $"{baseDir}/{i:D2}.{extension}";
         }
     }
 
@@ -205,27 +210,35 @@ public string[] SaveTestOutputFileMultiFrame<TPixel>(
         string extension = "png",
         IImageEncoder encoder = null,
         object testOutputDetails = null,
-        bool appendPixelTypeToFileName = true)
+        bool appendPixelTypeToFileName = true,
+        Func<int, int, bool> predicate = null)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        encoder = encoder ?? TestEnvironment.GetReferenceEncoder($"foo.{extension}");
+        encoder ??= TestEnvironment.GetReferenceEncoder($"foo.{extension}");
 
         string[] files = this.GetTestOutputFileNamesMultiFrame(
             image.Frames.Count,
             extension,
             testOutputDetails,
-            appendPixelTypeToFileName).ToArray();
+            appendPixelTypeToFileName,
+            predicate: predicate).ToArray();
 
         for (int i = 0; i < image.Frames.Count; i++)
         {
-            using (Image<TPixel> frameImage = image.Frames.CloneFrame(i))
+            if (predicate != null && !predicate(i, image.Frames.Count))
             {
-                string filePath = files[i];
-                using (FileStream stream = File.OpenWrite(filePath))
-                {
-                    frameImage.Save(stream, encoder);
-                }
+                continue;
             }
+
+            if (i >= files.Length)
+            {
+                break;
+            }
+
+            using Image<TPixel> frameImage = image.Frames.CloneFrame(i);
+            string filePath = files[i];
+            using FileStream stream = File.OpenWrite(filePath);
+            frameImage.Save(stream, encoder);
         }
 
         return files;
@@ -236,20 +249,17 @@ internal string GetReferenceOutputFileName(
         object testOutputDetails,
         bool appendPixelTypeToFileName,
         bool appendSourceFileOrDescription)
-    {
-        return TestEnvironment.GetReferenceOutputFileName(
+        => TestEnvironment.GetReferenceOutputFileName(
             this.GetTestOutputFileName(extension, testOutputDetails, appendPixelTypeToFileName, appendSourceFileOrDescription));
-    }
 
     public string[] GetReferenceOutputFileNamesMultiFrame(
         int frameCount,
         string extension,
         object testOutputDetails,
-        bool appendPixelTypeToFileName = true)
-    {
-        return this.GetTestOutputFileNamesMultiFrame(frameCount, extension, testOutputDetails)
-            .Select(TestEnvironment.GetReferenceOutputFileName).ToArray();
-    }
+        bool appendPixelTypeToFileName = true,
+        Func<int, int, bool> predicate = null)
+        => this.GetTestOutputFileNamesMultiFrame(frameCount, extension, testOutputDetails, appendPixelTypeToFileName, predicate: predicate)
+        .Select(TestEnvironment.GetReferenceOutputFileName).ToArray();
 
     internal void Init(string typeName, string methodName, string outputSubfolderName)
     {

tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs

@@ -67,10 +67,10 @@ public static Image DebugSave(
         provider.Utility.SaveTestOutputFile(
             image,
             extension,
+            encoder: encoder,
             testOutputDetails: testOutputDetails,
             appendPixelTypeToFileName: appendPixelTypeToFileName,
-            appendSourceFileOrDescription: appendSourceFileOrDescription,
-            encoder: encoder);
+            appendSourceFileOrDescription: appendSourceFileOrDescription);
         return image;
     }
 
@@ -107,7 +107,8 @@ public static Image<TPixel> DebugSaveMultiFrame<TPixel>(
         ITestImageProvider provider,
         object testOutputDetails = null,
         string extension = "png",
-        bool appendPixelTypeToFileName = true)
+        bool appendPixelTypeToFileName = true,
+        Func<int, int, bool> predicate = null)
         where TPixel : unmanaged, IPixel<TPixel>
     {
         if (TestEnvironment.RunsWithCodeCoverage)
@@ -119,7 +120,8 @@ public static Image<TPixel> DebugSaveMultiFrame<TPixel>(
             image,
             extension,
             testOutputDetails: testOutputDetails,
-            appendPixelTypeToFileName: appendPixelTypeToFileName);
+            appendPixelTypeToFileName: appendPixelTypeToFileName,
+            predicate: predicate);
 
         return image;
     }
@@ -237,7 +239,6 @@ public static Image<TPixel> CompareFirstFrameToReferenceOutput<TPixel>(
         ITestImageProvider provider,
         FormattableString testOutputDetails,
         string extension = "png",
-        bool grayscale = false,
         bool appendPixelTypeToFileName = true,
         bool appendSourceFileOrDescription = true)
         where TPixel : unmanaged, IPixel<TPixel>
@@ -246,7 +247,6 @@ public static Image<TPixel> CompareFirstFrameToReferenceOutput<TPixel>(
             provider,
             (object)testOutputDetails,
             extension,
-            grayscale,
             appendPixelTypeToFileName,
             appendSourceFileOrDescription);
 
@@ -256,12 +256,11 @@ public static Image<TPixel> CompareFirstFrameToReferenceOutput<TPixel>(
         ITestImageProvider provider,
         object testOutputDetails = null,
         string extension = "png",
-        bool grayscale = false,
         bool appendPixelTypeToFileName = true,
         bool appendSourceFileOrDescription = true)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        using (var firstFrameOnlyImage = new Image<TPixel>(image.Width, image.Height))
+        using (Image<TPixel> firstFrameOnlyImage = new(image.Width, image.Height))
         using (Image<TPixel> referenceImage = GetReferenceOutputImage<TPixel>(
             provider,
             testOutputDetails,
@@ -284,18 +283,19 @@ public static Image<TPixel> CompareToReferenceOutputMultiFrame<TPixel>(
         ImageComparer comparer,
         object testOutputDetails = null,
         string extension = "png",
-        bool grayscale = false,
-        bool appendPixelTypeToFileName = true)
+        bool appendPixelTypeToFileName = true,
+        Func<int, int, bool> predicate = null)
         where TPixel : unmanaged, IPixel<TPixel>
     {
         using (Image<TPixel> referenceImage = GetReferenceOutputImageMultiFrame<TPixel>(
             provider,
             image.Frames.Count,
             testOutputDetails,
             extension,
-            appendPixelTypeToFileName))
+            appendPixelTypeToFileName,
+            predicate: predicate))
         {
-            comparer.VerifySimilarity(referenceImage, image);
+            comparer.VerifySimilarity(referenceImage, image, predicate);
         }
 
         return image;
@@ -332,16 +332,18 @@ public static Image<TPixel> GetReferenceOutputImageMultiFrame<TPixel>(
         int frameCount,
         object testOutputDetails = null,
         string extension = "png",
-        bool appendPixelTypeToFileName = true)
+        bool appendPixelTypeToFileName = true,
+        Func<int, int, bool> predicate = null)
         where TPixel : unmanaged, IPixel<TPixel>
     {
         string[] frameFiles = provider.Utility.GetReferenceOutputFileNamesMultiFrame(
             frameCount,
             extension,
             testOutputDetails,
-            appendPixelTypeToFileName);
+            appendPixelTypeToFileName,
+            predicate);
 
-        var temporaryFrameImages = new List<Image<TPixel>>();
+        List<Image<TPixel>> temporaryFrameImages = new();
 
         IImageDecoder decoder = TestEnvironment.GetReferenceDecoder(frameFiles[0]);
 
@@ -359,7 +361,7 @@ public static Image<TPixel> GetReferenceOutputImageMultiFrame<TPixel>(
 
         Image<TPixel> firstTemp = temporaryFrameImages[0];
 
-        var result = new Image<TPixel>(firstTemp.Width, firstTemp.Height);
+        Image<TPixel> result = new(firstTemp.Width, firstTemp.Height);
 
         foreach (Image<TPixel> fi in temporaryFrameImages)
         {