Add exception type and update xml docs.

src/ImageSharp/Common/Exceptions/InvalidImageContentException.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// The exception that is thrown when the library tries to load
+    /// an image which contains invalid content.
+    /// </summary>
+    public sealed class InvalidImageContentException : ImageFormatException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="InvalidImageContentException"/> class with the name of the
+        /// parameter that causes this exception.
+        /// </summary>
+        /// <param name="errorMessage">The error message that explains the reason for this exception.</param>
+        public InvalidImageContentException(string errorMessage)
+            : base(errorMessage)
+        {
+        }
+    }
+}

src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs

@@ -462,7 +462,7 @@ private void UncompressRle4(int w, Span<byte> buffer, Span<bool> undefinedPixels
             {
                 if (this.stream.Read(cmd, 0, cmd.Length) != 2)
                 {
-                    BmpThrowHelper.ThrowImageFormatException("Failed to read 2 bytes from the stream while uncompressing RLE4 bitmap.");
+                    BmpThrowHelper.ThrowInvalidImageContentException("Failed to read 2 bytes from the stream while uncompressing RLE4 bitmap.");
                 }
 
                 if (cmd[0] == RleCommand)
@@ -569,7 +569,7 @@ private void UncompressRle8(int w, Span<byte> buffer, Span<bool> undefinedPixels
             {
                 if (this.stream.Read(cmd, 0, cmd.Length) != 2)
                 {
-                    BmpThrowHelper.ThrowImageFormatException("Failed to read 2 bytes from stream while uncompressing RLE8 bitmap.");
+                    BmpThrowHelper.ThrowInvalidImageContentException("Failed to read 2 bytes from stream while uncompressing RLE8 bitmap.");
                 }
 
                 if (cmd[0] == RleCommand)
@@ -648,7 +648,7 @@ private void UncompressRle24(int w, Span<byte> buffer, Span<bool> undefinedPixel
             {
                 if (this.stream.Read(cmd, 0, cmd.Length) != 2)
                 {
-                    BmpThrowHelper.ThrowImageFormatException("Failed to read 2 bytes from stream while uncompressing RLE24 bitmap.");
+                    BmpThrowHelper.ThrowInvalidImageContentException("Failed to read 2 bytes from stream while uncompressing RLE24 bitmap.");
                 }
 
                 if (cmd[0] == RleCommand)
@@ -1431,7 +1431,7 @@ private int ReadImageHeaders(Stream stream, out bool inverted, out byte[] palett
                 // Make sure, that we will not read pass the bitmap offset (starting position of image data).
                 if ((this.stream.Position + colorMapSizeBytes) > this.fileHeader.Offset)
                 {
-                    BmpThrowHelper.ThrowImageFormatException(
+                    BmpThrowHelper.ThrowInvalidImageContentException(
                         $"Reading the color map would read beyond the bitmap offset. Either the color map size of '{colorMapSizeBytes}' is invalid or the bitmap offset.");
                 }
 
@@ -1445,7 +1445,7 @@ private int ReadImageHeaders(Stream stream, out bool inverted, out byte[] palett
             int skipAmount = this.fileHeader.Offset - (int)this.stream.Position;
             if ((skipAmount + (int)this.stream.Position) > this.stream.Length)
             {
-                BmpThrowHelper.ThrowImageFormatException("Invalid fileheader offset found. Offset is greater than the stream length.");
+                BmpThrowHelper.ThrowInvalidImageContentException("Invalid fileheader offset found. Offset is greater than the stream length.");
             }
 
             if (skipAmount > 0)

src/ImageSharp/Formats/Bmp/BmpInfoHeader.cs

@@ -393,7 +393,7 @@ public static BmpInfoHeader ParseOs2Version2(ReadOnlySpan<byte> data)
                     break;
                 default:
                     // Compression type 3 (1DHuffman) is not supported.
-                    BmpThrowHelper.ThrowImageFormatException("Compression type is not supported. ImageSharp only supports uncompressed, RLE4, RLE8 and RLE24.");
+                    BmpThrowHelper.ThrowInvalidImageContentException("Compression type is not supported. ImageSharp only supports uncompressed, RLE4, RLE8 and RLE24.");
                     break;
             }
 

src/ImageSharp/Formats/Bmp/BmpThrowHelper.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -9,23 +9,19 @@ namespace SixLabors.ImageSharp.Formats.Bmp
     internal static class BmpThrowHelper
     {
         /// <summary>
-        /// Cold path optimization for throwing <see cref="ImageFormatException"/>-s
+        /// Cold path optimization for throwing <see cref="InvalidImageContentException"/>'s
         /// </summary>
         /// <param name="errorMessage">The error message for the exception.</param>
         [MethodImpl(MethodImplOptions.NoInlining)]
-        public static void ThrowImageFormatException(string errorMessage)
-        {
-            throw new ImageFormatException(errorMessage);
-        }
+        public static void ThrowInvalidImageContentException(string errorMessage)
+            => throw new InvalidImageContentException(errorMessage);
 
         /// <summary>
-        /// Cold path optimization for throwing <see cref="NotSupportedException"/>-s
+        /// Cold path optimization for throwing <see cref="NotSupportedException"/>'s
         /// </summary>
         /// <param name="errorMessage">The error message for the exception.</param>
         [MethodImpl(MethodImplOptions.NoInlining)]
         public static void ThrowNotSupportedException(string errorMessage)
-        {
-            throw new NotSupportedException(errorMessage);
-        }
+            => throw new NotSupportedException(errorMessage);
     }
 }

src/ImageSharp/Formats/Gif/GifDecoderCore.cs

@@ -318,7 +318,7 @@ private void ReadComments()
             {
                 if (length > GifConstants.MaxCommentSubBlockLength)
                 {
-                    throw new ImageFormatException($"Gif comment length '{length}' exceeds max '{GifConstants.MaxCommentSubBlockLength}' of a comment data block");
+                    GifThrowHelper.ThrowInvalidImageContentException($"Gif comment length '{length}' exceeds max '{GifConstants.MaxCommentSubBlockLength}' of a comment data block");
                 }
 
                 if (this.IgnoreMetadata)

src/ImageSharp/Formats/Gif/GifThrowHelper.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Runtime.CompilerServices;
+
+namespace SixLabors.ImageSharp.Formats.Gif
+{
+    internal static class GifThrowHelper
+    {
+        /// <summary>
+        /// Cold path optimization for throwing <see cref="InvalidImageContentException"/>'s
+        /// </summary>
+        /// <param name="errorMessage">The error message for the exception.</param>
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        public static void ThrowInvalidImageContentException(string errorMessage)
+            => throw new InvalidImageContentException(errorMessage);
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimd.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -104,7 +104,7 @@ internal static void ConvertCore(in ComponentValues values, Span<Vector4> result
                     {
                         // TODO: Run fallback scalar code here
                         // However, no issues expected before someone implements this: https://github.com/dotnet/coreclr/issues/12007
-                        throw new NotImplementedException("Your CPU architecture is too modern!");
+                        JpegThrowHelper.ThrowNotImplementedException("Your CPU architecture is too modern!");
                     }
 
                     // Collect (r0,r1...r8) (g0,g1...g8) (b0,b1...b8) vector values in the expected (r0,g0,g1,1), (r1,g1,g2,1) ... order:

src/ImageSharp/Formats/Jpeg/Components/Decoder/JFifMarker.cs

@@ -29,12 +29,12 @@ private JFifMarker(byte majorVersion, byte minorVersion, byte densityUnits, shor
         {
             if (xDensity <= 0)
             {
-                JpegThrowHelper.ThrowImageFormatException($"X-Density {xDensity} must be greater than 0.");
+                JpegThrowHelper.ThrowInvalidImageContentException($"X-Density {xDensity} must be greater than 0.");
             }
 
             if (yDensity <= 0)
             {
-                JpegThrowHelper.ThrowImageFormatException($"Y-Density {yDensity} must be greater than 0.");
+                JpegThrowHelper.ThrowInvalidImageContentException($"Y-Density {yDensity} must be greater than 0.");
             }
 
             this.MajorVersion = majorVersion;

src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

@@ -259,7 +259,7 @@ public void ParseStream(Stream stream, bool metadataOnly = false)
             var fileMarker = new JpegFileMarker(this.markerBuffer[1], 0);
             if (fileMarker.Marker != JpegConstants.Markers.SOI)
             {
-                JpegThrowHelper.ThrowImageFormatException("Missing SOI marker.");
+                JpegThrowHelper.ThrowInvalidImageContentException("Missing SOI marker.");
             }
 
             this.InputStream.Read(this.markerBuffer, 0, 2);
@@ -423,7 +423,7 @@ private JpegColorSpace DeduceJpegColorSpace()
                     : JpegColorSpace.Cmyk;
             }
 
-            JpegThrowHelper.ThrowImageFormatException($"Unsupported color mode. Supported component counts 1, 3, and 4; found {this.ComponentCount}");
+            JpegThrowHelper.ThrowInvalidImageContentException($"Unsupported color mode. Supported component counts 1, 3, and 4; found {this.ComponentCount}");
             return default;
         }
 
@@ -821,7 +821,7 @@ private void ProcessStartOfFrameMarker(int remaining, in JpegFileMarker frameMar
         {
             if (this.Frame != null)
             {
-                JpegThrowHelper.ThrowImageFormatException("Multiple SOF markers. Only single frame jpegs supported.");
+                JpegThrowHelper.ThrowInvalidImageContentException("Multiple SOF markers. Only single frame jpegs supported.");
             }
 
             // Read initial marker definitions.
@@ -831,7 +831,7 @@ private void ProcessStartOfFrameMarker(int remaining, in JpegFileMarker frameMar
             // We only support 8-bit and 12-bit precision.
             if (Array.IndexOf(this.supportedPrecisions, this.temp[0]) == -1)
             {
-                JpegThrowHelper.ThrowImageFormatException("Only 8-Bit and 12-Bit precision supported.");
+                JpegThrowHelper.ThrowInvalidImageContentException("Only 8-Bit and 12-Bit precision supported.");
             }
 
             this.Precision = this.temp[0];
@@ -928,13 +928,13 @@ private void ProcessDefineHuffmanTablesMarker(int remaining)
                     // Types 0..1 DC..AC
                     if (tableType > 1)
                     {
-                        JpegThrowHelper.ThrowImageFormatException("Bad Huffman Table type.");
+                        JpegThrowHelper.ThrowInvalidImageContentException("Bad Huffman Table type.");
                     }
 
                     // Max tables of each type
                     if (tableIndex > 3)
                     {
-                        JpegThrowHelper.ThrowImageFormatException("Bad Huffman Table index.");
+                        JpegThrowHelper.ThrowInvalidImageContentException("Bad Huffman Table index.");
                     }
 
                     this.InputStream.Read(huffmanData.Array, 0, 16);
@@ -953,7 +953,7 @@ private void ProcessDefineHuffmanTablesMarker(int remaining)
 
                         if (codeLengthSum > 256 || codeLengthSum > length)
                         {
-                            JpegThrowHelper.ThrowImageFormatException("Huffman table has excessive length.");
+                            JpegThrowHelper.ThrowInvalidImageContentException("Huffman table has excessive length.");
                         }
 
                         using (IManagedByteBuffer huffmanValues = this.configuration.MemoryAllocator.AllocateManagedByteBuffer(256, AllocationOptions.Clean))
@@ -995,7 +995,7 @@ private void ProcessStartOfScanMarker()
         {
             if (this.Frame is null)
             {
-                JpegThrowHelper.ThrowImageFormatException("No readable SOFn (Start Of Frame) marker found.");
+                JpegThrowHelper.ThrowInvalidImageContentException("No readable SOFn (Start Of Frame) marker found.");
             }
 
             int selectorsCount = this.InputStream.ReadByte();
@@ -1016,7 +1016,7 @@ private void ProcessStartOfScanMarker()
 
                 if (componentIndex < 0)
                 {
-                    JpegThrowHelper.ThrowImageFormatException($"Unknown component selector {componentIndex}.");
+                    JpegThrowHelper.ThrowInvalidImageContentException($"Unknown component selector {componentIndex}.");
                 }
 
                 ref JpegComponent component = ref this.Frame.Components[componentIndex];

src/ImageSharp/Formats/Jpeg/JpegThrowHelper.cs

@@ -1,32 +1,41 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Runtime.CompilerServices;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg
 {
     internal static class JpegThrowHelper
     {
         /// <summary>
-        /// Cold path optimization for throwing <see cref="ImageFormatException"/>'s.
+        /// Cold path optimization for throwing <see cref="InvalidImageContentException"/>'s.
         /// </summary>
         /// <param name="errorMessage">The error message for the exception.</param>
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowImageFormatException(string errorMessage) => throw new ImageFormatException(errorMessage);
+        public static void ThrowInvalidImageContentException(string errorMessage) => throw new InvalidImageContentException(errorMessage);
+
+        /// <summary>
+        /// Cold path optimization for throwing <see cref="NotImplementedException"/>'s
+        /// </summary>
+        /// <param name="errorMessage">The error message for the exception.</param>
+        [MethodImpl(InliningOptions.ColdPath)]
+        public static void ThrowNotImplementedException(string errorMessage)
+            => throw new NotImplementedException(errorMessage);
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowBadMarker(string marker, int length) => throw new ImageFormatException($"Marker {marker} has bad length {length}.");
+        public static void ThrowBadMarker(string marker, int length) => throw new InvalidImageContentException($"Marker {marker} has bad length {length}.");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowBadQuantizationTable() => throw new ImageFormatException("Bad Quantization Table index.");
+        public static void ThrowBadQuantizationTable() => throw new InvalidImageContentException("Bad Quantization Table index.");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowBadSampling() => throw new ImageFormatException("Bad sampling factor.");
+        public static void ThrowBadSampling() => throw new InvalidImageContentException("Bad sampling factor.");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowBadProgressiveScan(int ss, int se, int ah, int al) => throw new ImageFormatException($"Invalid progressive parameters Ss={ss} Se={se} Ah={ah} Al={al}.");
+        public static void ThrowBadProgressiveScan(int ss, int se, int ah, int al) => throw new InvalidImageContentException($"Invalid progressive parameters Ss={ss} Se={se} Ah={ah} Al={al}.");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowInvalidImageDimensions(int width, int height) => throw new ImageFormatException($"Invalid image dimensions: {width}x{height}.");
+        public static void ThrowInvalidImageDimensions(int width, int height) => throw new InvalidImageContentException($"Invalid image dimensions: {width}x{height}.");
     }
-}
+}

src/ImageSharp/Formats/Png/PngThrowHelper.cs

@@ -12,21 +12,21 @@ namespace SixLabors.ImageSharp.Formats.Png
     internal static class PngThrowHelper
     {
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowNoHeader() => throw new ImageFormatException("PNG Image does not contain a header chunk");
+        public static void ThrowNoHeader() => throw new InvalidImageContentException("PNG Image does not contain a header chunk");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowNoData() => throw new ImageFormatException("PNG Image does not contain a data chunk");
+        public static void ThrowNoData() => throw new InvalidImageContentException("PNG Image does not contain a data chunk");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowInvalidChunkType() => throw new ImageFormatException("Invalid PNG data.");
+        public static void ThrowInvalidChunkType() => throw new InvalidImageContentException("Invalid PNG data.");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowInvalidChunkCrc(string chunkTypeName) => throw new ImageFormatException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
+        public static void ThrowInvalidChunkCrc(string chunkTypeName) => throw new InvalidImageContentException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
 
         [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowNotSupportedColor() => new NotSupportedException("Unsupported PNG color type");
 
         [MethodImpl(InliningOptions.ColdPath)]
-        public static void ThrowUnknownFilter() => throw new ImageFormatException("Unknown filter type.");
+        public static void ThrowUnknownFilter() => throw new InvalidImageContentException("Unknown filter type.");
     }
 }

src/ImageSharp/Formats/Tga/TgaDecoderCore.cs

@@ -114,12 +114,12 @@ public Image<TPixel> Decode<TPixel>(Stream stream)
                 {
                     if (this.fileHeader.CMapLength <= 0)
                     {
-                        TgaThrowHelper.ThrowImageFormatException("Missing tga color map length");
+                        TgaThrowHelper.ThrowInvalidImageContentException("Missing tga color map length");
                     }
 
                     if (this.fileHeader.CMapDepth <= 0)
                     {
-                        TgaThrowHelper.ThrowImageFormatException("Missing tga color map depth");
+                        TgaThrowHelper.ThrowInvalidImageContentException("Missing tga color map depth");
                     }
 
                     int colorMapPixelSizeInBytes = this.fileHeader.CMapDepth / 8;
@@ -898,7 +898,7 @@ private TgaImageOrigin ReadFileHeader(Stream stream)
             var alphaBits = this.fileHeader.ImageDescriptor & 0xf;
             if (alphaBits != 0 && alphaBits != 1 && alphaBits != 8)
             {
-                TgaThrowHelper.ThrowImageFormatException("Invalid alpha channel bits");
+                TgaThrowHelper.ThrowInvalidImageContentException("Invalid alpha channel bits");
             }
 
             this.tgaMetadata.AlphaChannelBits = (byte)alphaBits;