sync with upstream

src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs

@@ -2,6 +2,7 @@
 // Copyright (c) James Jackson-South and contributors.
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
+
 namespace ImageSharp.Formats
 {
     using System;
@@ -135,11 +136,6 @@ namespace ImageSharp.Formats
                     switch (this.infoHeader.Compression)
                     {
                         case BmpCompression.RGB:
-                            if (this.infoHeader.HeaderSize != 40)
-                            {
-                                throw new ImageFormatException($"Header Size value '{this.infoHeader.HeaderSize}' is not valid.");
-                            }
-
                             if (this.infoHeader.BitsPerPixel == 32)
                             {
                                 this.ReadRgb32(pixels, this.infoHeader.Width, this.infoHeader.Height, inverted);
@@ -374,11 +370,69 @@ namespace ImageSharp.Formats
         /// </summary>
         private void ReadInfoHeader()
         {
-            byte[] data = new byte[BmpInfoHeader.Size];
+            byte[] data = new byte[BmpInfoHeader.MaxHeaderSize];
+
+            // read header size
+            this.currentStream.Read(data, 0, BmpInfoHeader.HeaderSizeSize);
+            int headerSize = BitConverter.ToInt32(data, 0);
+            if (headerSize < BmpInfoHeader.HeaderSizeSize || headerSize > BmpInfoHeader.MaxHeaderSize)
+            {
+                throw new NotSupportedException($"This kind of bitmap files (header size $headerSize) is not supported.");
+            }
+
+            // read the rest of the header
+            this.currentStream.Read(data, BmpInfoHeader.HeaderSizeSize, headerSize - BmpInfoHeader.HeaderSizeSize);
+
+            switch (headerSize)
+            {
+                case BmpInfoHeader.BitmapCoreHeaderSize:
+                    this.infoHeader = this.ParseBitmapCoreHeader(data);
+                    break;
+
+                case BmpInfoHeader.BitmapInfoHeaderSize:
+                    this.infoHeader = this.ParseBitmapInfoHeader(data);
+                    break;
+
+                default:
+                    throw new NotSupportedException($"This kind of bitmap files (header size $headerSize) is not supported.");
+            }
+        }
 
-            this.currentStream.Read(data, 0, BmpInfoHeader.Size);
+        /// <summary>
+        /// Parses the <see cref="BmpInfoHeader"/> from the stream, assuming it uses the BITMAPCOREHEADER format.
+        /// </summary>
+        /// <param name="data">Header bytes read from the stream</param>
+        /// <returns>Parsed header</returns>
+        /// <seealso href="https://msdn.microsoft.com/en-us/library/windows/desktop/dd183372.aspx"/>
+        private BmpInfoHeader ParseBitmapCoreHeader(byte[] data)
+        {
+            return new BmpInfoHeader
+            {
+                HeaderSize = BitConverter.ToInt32(data, 0),
+                Width = BitConverter.ToUInt16(data, 4),
+                Height = BitConverter.ToUInt16(data, 6),
+                Planes = BitConverter.ToInt16(data, 8),
+                BitsPerPixel = BitConverter.ToInt16(data, 10),
+
+                // the rest is not present in the core header
+                ImageSize = 0,
+                XPelsPerMeter = 0,
+                YPelsPerMeter = 0,
+                ClrUsed = 0,
+                ClrImportant = 0,
+                Compression = BmpCompression.RGB
+            };
+        }
 
-            this.infoHeader = new BmpInfoHeader
+        /// <summary>
+        /// Parses the <see cref="BmpInfoHeader"/> from the stream, assuming it uses the BITMAPINFOHEADER format.
+        /// </summary>
+        /// <param name="data">Header bytes read from the stream</param>
+        /// <returns>Parsed header</returns>
+        /// <seealso href="https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376.aspx"/>
+        private BmpInfoHeader ParseBitmapInfoHeader(byte[] data)
+        {
+            return new BmpInfoHeader
             {
                 HeaderSize = BitConverter.ToInt32(data, 0),
                 Width = BitConverter.ToInt32(data, 4),

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -58,7 +58,7 @@ namespace ImageSharp.Formats
 
             BmpInfoHeader infoHeader = new BmpInfoHeader
             {
-                HeaderSize = BmpInfoHeader.Size,
+                HeaderSize = BmpInfoHeader.BitmapInfoHeaderSize,
                 Height = image.Height,
                 Width = image.Width,
                 BitsPerPixel = bpp,

src/ImageSharp/Formats/Bmp/BmpInfoHeader.cs

@@ -13,12 +13,27 @@ namespace ImageSharp.Formats
     internal sealed class BmpInfoHeader
     {
         /// <summary>
-        /// Defines of the data structure in the bitmap file.
+        /// Defines the size of the BITMAPINFOHEADER data structure in the bitmap file.
         /// </summary>
-        public const int Size = 40;
+        public const int BitmapInfoHeaderSize = 40;
 
         /// <summary>
-        /// Gets or sets the size of this header (40 bytes)
+        /// Defines the size of the BITMAPCOREHEADER data structure in the bitmap file.
+        /// </summary>
+        public const int BitmapCoreHeaderSize = 12;
+
+        /// <summary>
+        /// Defines the size of the biggest supported header data structure in the bitmap file.
+        /// </summary>
+        public const int MaxHeaderSize = BitmapInfoHeaderSize;
+
+        /// <summary>
+        /// Defines the size of the <see cref="HeaderSize"/> field.
+        /// </summary>
+        public const int HeaderSizeSize = 4;
+
+        /// <summary>
+        /// Gets or sets the size of this header
         /// </summary>
         public int HeaderSize { get; set; }
 

tests/ImageSharp.Tests/FileTestBase.cs

@@ -77,6 +77,7 @@ namespace ImageSharp.Tests
             // TestFile.Create(TestImages.Jpeg.Progressive.Bad.BadEOF), // Perf: Enable for local testing only
                TestFile.Create(TestImages.Bmp.Car),
             // TestFile.Create(TestImages.Bmp.NegHeight), // Perf: Enable for local testing only
+            // TestFile.Create(TestImages.Bmp.CoreHeader), // Perf: Enable for local testing only
                TestFile.Create(TestImages.Png.Splash),
             // TestFile.Create(TestImages.Png.Cross), // Perf: Enable for local testing only
             // TestFile.Create(TestImages.Png.Bad.ChunkLength1), // Perf: Enable for local testing only

tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs

@@ -1,17 +1,29 @@
-// <copyright file="GifDecoderTests.cs" company="James Jackson-South">
+// <copyright file="BmpDecoderTests.cs" company="James Jackson-South">
 // Copyright (c) James Jackson-South and contributors.
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
 
-// ReSharper disable InconsistentNaming
+using ImageSharp.Formats;
+
 namespace ImageSharp.Tests
 {
-    using System.IO;
+    using ImageSharp.PixelFormats;
 
     using Xunit;
 
-    public class BmpDecoderTests
+    public class BmpDecoderTests : FileTestBase
     {
+        [Theory]
+        [WithFileCollection(nameof(AllBmpFiles), PixelTypes.Rgb24)]
+        public void OpenAllBmpFiles_SaveBmp<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                provider.Utility.SaveTestOutputFile(image, "bmp");
+            }
+        }
+
         [Theory]
         [InlineData(TestImages.Bmp.Car, 24)]
         [InlineData(TestImages.Bmp.F, 24)]
@@ -26,4 +38,4 @@ namespace ImageSharp.Tests
             }
         }
     }
-}
+}

tests/ImageSharp.Tests/TestImages.cs

@@ -120,7 +120,8 @@ namespace ImageSharp.Tests
             public const string F = "Bmp/F.bmp";
             public const string Bpp8 = "Bmp/bpp8.bmp";
             public const string NegHeight = "Bmp/neg_height.bmp";
-            public static readonly string[] All = { Car, F, NegHeight, Bpp8 };
+            public const string CoreHeader = "Bmp/BitmapCoreHeaderQR.bmp";
+            public static readonly string[] All = { Car, F, NegHeight, CoreHeader, Bpp8 };
         }
 
         public static class Gif

tests/ImageSharp.Tests/TestImages/Formats/Bmp/BitmapCoreHeaderQR.bmp

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:04709a3b7e9a73e87f12c5c63f66bc608e3cd61c23fcd38629bb8638bbb1b4de
+size 2580