Add png tests

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

@@ -4,7 +4,6 @@
 using System.Text;
 using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.PixelFormats;
-using SixLabors.Primitives;
 using Xunit;
 using System.IO;
 using SixLabors.ImageSharp.Advanced;

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -8,6 +8,7 @@ using System.IO;
 using System.Text;
 
 using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 
@@ -18,8 +19,8 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
     public partial class PngDecoderTests
     {
         private const PixelTypes PixelTypes = Tests.PixelTypes.Rgba32 | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
-        
-        
+
+
 
         public static readonly string[] CommonTestImages =
         {
@@ -67,6 +68,14 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             TestImages.Png.GrayTrns16BitInterlaced
         };
 
+        public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
+        new TheoryData<string, int, int, PixelResolutionUnit>
+        {
+            { TestImages.Png.Splash, 11810, 11810 , PixelResolutionUnit.PixelsPerMeter},
+            { TestImages.Png.Ratio1x4, 1, 4 , PixelResolutionUnit.AspectRatio},
+            { TestImages.Png.Ratio4x1, 4, 1, PixelResolutionUnit.AspectRatio }
+        };
+
         [Theory]
         [WithFileCollection(nameof(CommonTestImages), PixelTypes.Rgba32)]
         public void Decode<TPixel>(TestImageProvider<TPixel> provider)
@@ -218,5 +227,39 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
                 Assert.Equal(expectedPixelSize, Image.Identify(stream)?.PixelType?.BitsPerPixel);
             }
         }
+
+        [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 PngDecoder();
+                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 PngDecoder();
+                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);
+            }
+        }
     }
 }

tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs

@@ -7,6 +7,7 @@ using System.Linq;
 
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.MetaData;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Quantization;
@@ -61,6 +62,14 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             80, 100, 120, 230
         };
 
+        public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
+        new TheoryData<string, int, int, PixelResolutionUnit>
+        {
+            { TestImages.Png.Splash, 11810, 11810 , PixelResolutionUnit.PixelsPerMeter},
+            { TestImages.Png.Ratio1x4, 1, 4 , PixelResolutionUnit.AspectRatio},
+            { TestImages.Png.Ratio4x1, 4, 1, PixelResolutionUnit.AspectRatio }
+        };
+
         [Theory]
         [WithFile(TestImages.Png.Palette8Bpp, nameof(PngColorTypes), PixelTypes.Rgba32)]
         [WithTestPatternImages(nameof(PngColorTypes), 48, 24, PixelTypes.Rgba32)]
@@ -256,5 +265,30 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
                 Assert.Equal(expected, data);
             }
         }
+
+        [Theory]
+        [MemberData(nameof(RatioFiles))]
+        public void Encode_PreserveRatio(string imagePath, int xResolution, int yResolution, PixelResolutionUnit resolutionUnit)
+        {
+            var options = new PngEncoder();
+
+            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);
+                    }
+                }
+            }
+        }
     }
 }

tests/ImageSharp.Tests/TestImages.cs

@@ -65,6 +65,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Banner7Adam7InterlaceMode = "Png/banner7-adam.png";
             public const string Banner8Index = "Png/banner8-index.png";
 
+            public const string Ratio1x4 = "Png/ratio-1x4.png";
+            public const string Ratio4x1 = "Png/ratio-4x1.png";
+
             public static class Bad
             {
                 // Odd chunk lengths