Add gif tests

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

@@ -13,7 +13,7 @@ using SixLabors.ImageSharp.Advanced;
 namespace SixLabors.ImageSharp.Tests.Formats.Gif
 {
     using System.Collections.Generic;
-
+    using SixLabors.ImageSharp.MetaData;
     using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 
     public class GifDecoderTests
@@ -21,31 +21,43 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
         private const PixelTypes TestPixelTypes = PixelTypes.Rgba32 | PixelTypes.RgbaVector | PixelTypes.Argb32;
 
         public static readonly string[] MultiFrameTestFiles =
-            {
-                TestImages.Gif.Giphy, TestImages.Gif.Kumin
-            };
+        {
+            TestImages.Gif.Giphy, TestImages.Gif.Kumin
+        };
 
         public static readonly string[] BasicVerificationFiles =
-            {
-                TestImages.Gif.Cheers,
-                TestImages.Gif.Rings,
+        {
+            TestImages.Gif.Cheers,
+            TestImages.Gif.Rings,
 
-                // previously DecodeBadApplicationExtensionLength:
-                TestImages.Gif.Issues.BadAppExtLength,
-                TestImages.Gif.Issues.BadAppExtLength_2,
+            // previously DecodeBadApplicationExtensionLength:
+            TestImages.Gif.Issues.BadAppExtLength,
+            TestImages.Gif.Issues.BadAppExtLength_2,
 
-                // previously DecodeBadDescriptorDimensionsLength:
-                TestImages.Gif.Issues.BadDescriptorWidth
-            };
+            // previously DecodeBadDescriptorDimensionsLength:
+            TestImages.Gif.Issues.BadDescriptorWidth
+        };
+
+        public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
+        new TheoryData<string, int, int, PixelResolutionUnit>
+        {
+            { TestImages.Gif.Rings, (int)ImageMetaData.DefaultHorizontalResolution, (int)ImageMetaData.DefaultVerticalResolution , PixelResolutionUnit.PixelsPerInch},
+            { TestImages.Gif.Ratio1x4, 1, 4 , PixelResolutionUnit.AspectRatio},
+            { TestImages.Gif.Ratio4x1, 4, 1, PixelResolutionUnit.AspectRatio }
+        };
 
         private static readonly Dictionary<string, int> BasicVerificationFrameCount =
-            new Dictionary<string, int>
-                {
-                    [TestImages.Gif.Cheers] = 93,
-                    [TestImages.Gif.Issues.BadDescriptorWidth] = 36,
-            };
+        new Dictionary<string, int>
+        {
+            [TestImages.Gif.Cheers] = 93,
+            [TestImages.Gif.Issues.BadDescriptorWidth] = 36,
+        };
 
-        public static readonly string[] BadAppExtFiles = { TestImages.Gif.Issues.BadAppExtLength, TestImages.Gif.Issues.BadAppExtLength_2 };
+        public static readonly string[] BadAppExtFiles =
+        {
+            TestImages.Gif.Issues.BadAppExtLength,
+            TestImages.Gif.Issues.BadAppExtLength_2
+        };
 
         [Theory]
         [WithFileCollection(nameof(MultiFrameTestFiles), PixelTypes.Rgba32)]
@@ -59,6 +71,40 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
             }
         }
 
+        [Theory]
+        [MemberData(nameof(RatioFiles))]
+        public void Decode_VerifyRatio(string imagePath, int xResolution, int yResolution, PixelResolutionUnit resolutionUnit)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using (var stream = new MemoryStream(testFile.Bytes, false))
+            {
+                var decoder = new GifDecoder();
+                using (Image<Rgba32> image = decoder.Decode<Rgba32>(Configuration.Default, stream))
+                {
+                    ImageMetaData meta = image.MetaData;
+                    Assert.Equal(xResolution, meta.HorizontalResolution);
+                    Assert.Equal(yResolution, meta.VerticalResolution);
+                    Assert.Equal(resolutionUnit, meta.ResolutionUnits);
+                }
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(RatioFiles))]
+        public void Identify_VerifyRatio(string imagePath, int xResolution, int yResolution, PixelResolutionUnit resolutionUnit)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using (var stream = new MemoryStream(testFile.Bytes, false))
+            {
+                var decoder = new GifDecoder();
+                IImageInfo image = decoder.Identify(Configuration.Default, stream);
+                ImageMetaData meta = image.MetaData;
+                Assert.Equal(xResolution, meta.HorizontalResolution);
+                Assert.Equal(yResolution, meta.VerticalResolution);
+                Assert.Equal(resolutionUnit, meta.ResolutionUnits);
+            }
+        }
+
         [Theory]
         [WithFile(TestImages.Gif.Trans, TestPixelTypes)]
         public void GifDecoder_IsNotBoundToSinglePixelType<TPixel>(TestImageProvider<TPixel> provider)
@@ -88,7 +134,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
                 image.CompareFirstFrameToReferenceOutput(ImageComparer.Exact, provider);
             }
         }
-        
+
         [Fact]
         public void Decode_IgnoreMetadataIsFalse_CommentsAreRead()
         {
@@ -169,7 +215,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
         [InlineData(TestImages.Gif.Trans, 8)]
         public void DetectPixelSize(string imagePath, int expectedPixelSize)
         {
-            TestFile testFile = TestFile.Create(imagePath);
+            var testFile = TestFile.Create(imagePath);
             using (var stream = new MemoryStream(testFile.Bytes, false))
             {
                 Assert.Equal(expectedPixelSize, Image.Identify(stream)?.PixelType?.BitsPerPixel);

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

@@ -17,6 +17,14 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
         private const PixelTypes TestPixelTypes = PixelTypes.Rgba32 | PixelTypes.RgbaVector | PixelTypes.Argb32;
         private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.001F);
 
+        public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
+        new TheoryData<string, int, int, PixelResolutionUnit>
+        {
+            { TestImages.Gif.Rings, (int)ImageMetaData.DefaultHorizontalResolution, (int)ImageMetaData.DefaultVerticalResolution , PixelResolutionUnit.PixelsPerInch},
+            { TestImages.Gif.Ratio1x4, 1, 4 , PixelResolutionUnit.AspectRatio},
+            { TestImages.Gif.Ratio4x1, 4, 1, PixelResolutionUnit.AspectRatio }
+        };
+
         [Theory]
         [WithTestPatternImages(100, 100, TestPixelTypes)]
         public void EncodeGeneratedPatterns<TPixel>(TestImageProvider<TPixel> provider)
@@ -43,6 +51,34 @@ namespace SixLabors.ImageSharp.Tests.Formats.Gif
             }
         }
 
+        [Theory]
+        [MemberData(nameof(RatioFiles))]
+        public void Encode_PreserveRatio(string imagePath, int xResolution, int yResolution, PixelResolutionUnit resolutionUnit)
+        {
+            var options = new GifEncoder()
+            {
+                IgnoreMetadata = false
+            };
+
+            var testFile = TestFile.Create(imagePath);
+            using (Image<Rgba32> input = testFile.CreateImage())
+            {
+                using (var memStream = new MemoryStream())
+                {
+                    input.Save(memStream, options);
+
+                    memStream.Position = 0;
+                    using (var output = Image.Load<Rgba32>(memStream))
+                    {
+                        ImageMetaData meta = output.MetaData;
+                        Assert.Equal(xResolution, meta.HorizontalResolution);
+                        Assert.Equal(yResolution, meta.VerticalResolution);
+                        Assert.Equal(resolutionUnit, meta.ResolutionUnits);
+                    }
+                }
+            }
+        }
+
         [Fact]
         public void Encode_IgnoreMetadataIsFalse_CommentsAreWritten()
         {

tests/ImageSharp.Tests/TestImages.cs

@@ -176,6 +176,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Cheers = "Gif/cheers.gif";
             public const string Trans = "Gif/trans.gif";
             public const string Kumin = "Gif/kumin.gif";
+            public const string Ratio4x1 = "Gif/base_4x1.gif";
+            public const string Ratio1x4 = "Gif/base_1x4.gif";
+
 
             public class Issues
             {
@@ -184,7 +187,7 @@ namespace SixLabors.ImageSharp.Tests
                 public const string BadDescriptorWidth = "Gif/issues/issue403_baddescriptorwidth.gif";
             }
 
-            public static readonly string[] All = { Rings, Giphy, Cheers, Trans, Kumin };
+            public static readonly string[] All = { Rings, Giphy, Cheers, Trans, Kumin, Ratio4x1, Ratio1x4 };
         }
     }
 }