Add BigTiff into ConfigurationModule, add identify tests

src/ImageSharp/Formats/Tiff/TiffConfigurationModule.cs

@@ -14,6 +14,8 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             configuration.ImageFormatsManager.SetEncoder(TiffFormat.Instance, new TiffEncoder());
             configuration.ImageFormatsManager.SetDecoder(TiffFormat.Instance, new TiffDecoder());
             configuration.ImageFormatsManager.AddImageFormatDetector(new TiffImageFormatDetector(false));
+
+            configuration.ImageFormatsManager.AddImageFormatDetector(new TiffImageFormatDetector(true));
         }
     }
 }

tests/ImageSharp.Tests/Formats/Tiff/BigTiffDecoderTests.cs

@@ -3,6 +3,8 @@
 
 // ReSharper disable InconsistentNaming
 using System;
+using System.IO;
+using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.PixelFormats;
 
 using Xunit;
@@ -31,5 +33,54 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
         [WithFile(BigTIFFLong8Tiles, PixelTypes.Rgba32)]
         public void ThrowsNotSupported<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => Assert.Throws<NotSupportedException>(() => provider.GetImage(TiffDecoder));
+
+        [Theory]
+        [InlineData(BigTIFF, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFLong, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFLong8, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFMotorola, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFMotorolaLongStrips, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFSubIFD4, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        [InlineData(BigTIFFSubIFD8, 24, 64, 64, 96, 96, PixelResolutionUnit.PixelsPerInch)]
+        public void Identify(string imagePath, int expectedPixelSize, int expectedWidth, int expectedHeight, double expectedHResolution, double expectedVResolution, PixelResolutionUnit expectedResolutionUnit)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using (var stream = new MemoryStream(testFile.Bytes, false))
+            {
+                IImageInfo info = Image.Identify(stream);
+
+                Assert.Equal(expectedPixelSize, info.PixelType?.BitsPerPixel);
+                Assert.Equal(expectedWidth, info.Width);
+                Assert.Equal(expectedHeight, info.Height);
+                Assert.NotNull(info.Metadata);
+                Assert.Equal(expectedHResolution, info.Metadata.HorizontalResolution);
+                Assert.Equal(expectedVResolution, info.Metadata.VerticalResolution);
+                Assert.Equal(expectedResolutionUnit, info.Metadata.ResolutionUnits);
+
+                ImageSharp.Formats.Tiff.TiffMetadata tiffmeta = info.Metadata.GetTiffMetadata();
+                Assert.NotNull(tiffmeta);
+                Assert.True(tiffmeta.IsBigTiff);
+            }
+        }
+
+        [Theory]
+        [InlineData(BigTIFFLong, ImageSharp.ByteOrder.LittleEndian)]
+        [InlineData(BigTIFFMotorola, ImageSharp.ByteOrder.BigEndian)]
+        public void ByteOrder(string imagePath, ByteOrder expectedByteOrder)
+        {
+            var testFile = TestFile.Create(imagePath);
+            using (var stream = new MemoryStream(testFile.Bytes, false))
+            {
+                IImageInfo info = Image.Identify(stream);
+
+                Assert.NotNull(info.Metadata);
+                Assert.Equal(expectedByteOrder, info.Metadata.GetTiffMetadata().ByteOrder);
+
+                stream.Seek(0, SeekOrigin.Begin);
+
+                using var img = Image.Load(stream);
+                Assert.Equal(expectedByteOrder, img.Metadata.GetTiffMetadata().ByteOrder);
+            }
+        }
     }
 }