#2231 First steps for removing nullable disable in webp

Author: stefannikolei

src/ImageSharp/Formats/Webp/AlphaDecoder.cs

@@ -1,8 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics;
@@ -110,6 +110,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
     /// <summary>
     /// Gets a value indicating whether the alpha channel uses compression.
     /// </summary>
+    [MemberNotNullWhen(true, nameof(LosslessDecoder))]
     private bool Compressed { get; }
 
     /// <summary>
@@ -120,7 +121,7 @@ public AlphaDecoder(int width, int height, IMemoryOwner<byte> data, byte alphaCh
     /// <summary>
     /// Gets the Vp8L decoder which is used to de compress the alpha channel, if needed.
     /// </summary>
-    private WebpLosslessDecoder LosslessDecoder { get; }
+    private WebpLosslessDecoder? LosslessDecoder { get; }
 
     /// <summary>
     /// Gets a value indicating whether the decoding needs 1 byte per pixel for decoding.

src/ImageSharp/Formats/Webp/AlphaEncoder.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using SixLabors.ImageSharp.Advanced;
@@ -15,7 +14,7 @@ namespace SixLabors.ImageSharp.Formats.Webp;
 /// </summary>
 internal class AlphaEncoder : IDisposable
 {
-    private IMemoryOwner<byte> alphaData;
+    private IMemoryOwner<byte>? alphaData;
 
     /// <summary>
     /// Encodes the alpha channel data.

src/ImageSharp/Formats/Webp/BitReader/BitReaderBase.cs

@@ -1,8 +1,8 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
+using System.Diagnostics.CodeAnalysis;
 using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.Formats.Webp.BitReader;
@@ -17,14 +17,15 @@ internal abstract class BitReaderBase : IDisposable
     /// <summary>
     /// Gets or sets the raw encoded image data.
     /// </summary>
-    public IMemoryOwner<byte> Data { get; set; }
+    public IMemoryOwner<byte>? Data { get; set; }
 
     /// <summary>
     /// Copies the raw encoded image data from the stream into a byte array.
     /// </summary>
     /// <param name="input">The input stream.</param>
     /// <param name="bytesToRead">Number of bytes to read as indicated from the chunk size.</param>
     /// <param name="memoryAllocator">Used for allocating memory during reading data from the stream.</param>
+    [MemberNotNull(nameof(Data))]
     protected void ReadImageDataFromStream(Stream input, int bytesToRead, MemoryAllocator memoryAllocator)
     {
         this.Data = memoryAllocator.Allocate<byte>(bytesToRead);

src/ImageSharp/Formats/Webp/BitReader/Vp8BitReader.cs

@@ -186,7 +186,7 @@ private void LoadNewBytes()
     {
         if (this.pos < this.bufferMax)
         {
-            ulong inBits = BinaryPrimitives.ReadUInt64LittleEndian(this.Data.Memory.Span.Slice((int)this.pos, 8));
+            ulong inBits = BinaryPrimitives.ReadUInt64LittleEndian(this.Data!.Memory.Span.Slice((int)this.pos, 8));
             this.pos += BitsCount >> 3;
             ulong bits = ByteSwap64(inBits);
             bits >>= 64 - BitsCount;
@@ -205,7 +205,7 @@ private void LoadFinalBytes()
         if (this.pos < this.bufferEnd)
         {
             this.bits += 8;
-            this.value = this.Data.Memory.Span[(int)this.pos++] | (this.value << 8);
+            this.value = this.Data!.Memory.Span[(int)this.pos++] | (this.value << 8);
         }
         else if (!this.eof)
         {

src/ImageSharp/Formats/Webp/BitReader/Vp8LBitReader.cs

@@ -193,7 +193,7 @@ public void FillBitWindow()
     [MethodImpl(InliningOptions.ShortMethod)]
     private void ShiftBytes()
     {
-        System.Span<byte> dataSpan = this.Data.Memory.Span;
+        System.Span<byte> dataSpan = this.Data!.Memory.Span;
         while (this.bitPos >= 8 && this.pos < this.len)
         {
             this.value >>= 8;

src/ImageSharp/Formats/Webp/BitWriter/BitWriterBase.cs

@@ -123,7 +123,7 @@ protected static uint AlphaChunkSize(Span<byte> alphaBytes)
     /// <param name="stream">The stream to write to.</param>
     /// <param name="metadataBytes">The metadata profile's bytes.</param>
     /// <param name="chunkType">The chuck type to write.</param>
-    protected void WriteMetadataProfile(Stream stream, byte[] metadataBytes, WebpChunkType chunkType)
+    protected void WriteMetadataProfile(Stream stream, byte[]? metadataBytes, WebpChunkType chunkType)
     {
         DebugGuard.NotNull(metadataBytes, nameof(metadataBytes));
 
@@ -207,7 +207,7 @@ protected void WriteColorProfile(Stream stream, byte[] iccProfileBytes)
     /// <param name="width">The width of the image.</param>
     /// <param name="height">The height of the image.</param>
     /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
-    protected void WriteVp8XHeader(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, byte[] iccProfileBytes, uint width, uint height, bool hasAlpha)
+    protected void WriteVp8XHeader(Stream stream, ExifProfile? exifProfile, XmpProfile? xmpProfile, byte[]? iccProfileBytes, uint width, uint height, bool hasAlpha)
     {
         if (width > MaxDimension || height > MaxDimension)
         {

src/ImageSharp/Formats/Webp/BitWriter/Vp8BitWriter.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers.Binary;
 using SixLabors.ImageSharp.Formats.Webp.Lossy;
@@ -58,7 +57,8 @@ internal class Vp8BitWriter : BitWriterBase
     /// Initializes a new instance of the <see cref="Vp8BitWriter"/> class.
     /// </summary>
     /// <param name="expectedSize">The expected size in bytes.</param>
-    public Vp8BitWriter(int expectedSize)
+    /// <param name="enc">The Vp8Encoder.</param>
+    public Vp8BitWriter(int expectedSize, Vp8Encoder enc)
         : base(expectedSize)
     {
         this.range = 255 - 1;
@@ -67,15 +67,9 @@ public Vp8BitWriter(int expectedSize)
         this.nbBits = -8;
         this.pos = 0;
         this.maxPos = 0;
-    }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="Vp8BitWriter"/> class.
-    /// </summary>
-    /// <param name="expectedSize">The expected size in bytes.</param>
-    /// <param name="enc">The Vp8Encoder.</param>
-    public Vp8BitWriter(int expectedSize, Vp8Encoder enc)
-        : this(expectedSize) => this.enc = enc;
+        this.enc = enc;
+    }
 
     /// <inheritdoc/>
     public override int NumBytes() => (int)this.pos;
@@ -414,32 +408,32 @@ private void Flush()
     /// <param name="alphaDataIsCompressed">Indicates, if the alpha data is compressed.</param>
     public void WriteEncodedImageToStream(
         Stream stream,
-        ExifProfile exifProfile,
-        XmpProfile xmpProfile,
-        IccProfile iccProfile,
+        ExifProfile? exifProfile,
+        XmpProfile? xmpProfile,
+        IccProfile? iccProfile,
         uint width,
         uint height,
         bool hasAlpha,
         Span<byte> alphaData,
         bool alphaDataIsCompressed)
     {
         bool isVp8X = false;
-        byte[] exifBytes = null;
-        byte[] xmpBytes = null;
-        byte[] iccProfileBytes = null;
+        byte[]? exifBytes = null;
+        byte[]? xmpBytes = null;
+        byte[]? iccProfileBytes = null;
         uint riffSize = 0;
         if (exifProfile != null)
         {
             isVp8X = true;
             exifBytes = exifProfile.ToByteArray();
-            riffSize += MetadataChunkSize(exifBytes);
+            riffSize += MetadataChunkSize(exifBytes!);
         }
 
         if (xmpProfile != null)
         {
             isVp8X = true;
             xmpBytes = xmpProfile.Data;
-            riffSize += MetadataChunkSize(xmpBytes);
+            riffSize += MetadataChunkSize(xmpBytes!);
         }
 
         if (iccProfile != null)
@@ -465,7 +459,7 @@ public void WriteEncodedImageToStream(
         int mbSize = this.enc.Mbw * this.enc.Mbh;
         int expectedSize = mbSize * 7 / 8;
 
-        var bitWriterPartZero = new Vp8BitWriter(expectedSize);
+        Vp8BitWriter bitWriterPartZero = new(expectedSize, this.enc);
 
         // Partition #0 with header and partition sizes.
         uint size0 = this.GeneratePartition0(bitWriterPartZero);
@@ -676,9 +670,9 @@ private void WriteWebpHeaders(
         bool isVp8X,
         uint width,
         uint height,
-        ExifProfile exifProfile,
-        XmpProfile xmpProfile,
-        byte[] iccProfileBytes,
+        ExifProfile? exifProfile,
+        XmpProfile? xmpProfile,
+        byte[]? iccProfileBytes,
         bool hasAlpha,
         Span<byte> alphaData,
         bool alphaDataIsCompressed)

src/ImageSharp/Formats/Webp/BitWriter/Vp8LBitWriter.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers.Binary;
 using SixLabors.ImageSharp.Formats.Webp.Lossless;
@@ -138,25 +137,25 @@ public override void Finish()
     /// <param name="width">The width of the image.</param>
     /// <param name="height">The height of the image.</param>
     /// <param name="hasAlpha">Flag indicating, if a alpha channel is present.</param>
-    public void WriteEncodedImageToStream(Stream stream, ExifProfile exifProfile, XmpProfile xmpProfile, IccProfile iccProfile, uint width, uint height, bool hasAlpha)
+    public void WriteEncodedImageToStream(Stream stream, ExifProfile? exifProfile, XmpProfile? xmpProfile, IccProfile? iccProfile, uint width, uint height, bool hasAlpha)
     {
         bool isVp8X = false;
-        byte[] exifBytes = null;
-        byte[] xmpBytes = null;
-        byte[] iccBytes = null;
+        byte[]? exifBytes = null;
+        byte[]? xmpBytes = null;
+        byte[]? iccBytes = null;
         uint riffSize = 0;
         if (exifProfile != null)
         {
             isVp8X = true;
             exifBytes = exifProfile.ToByteArray();
-            riffSize += MetadataChunkSize(exifBytes);
+            riffSize += MetadataChunkSize(exifBytes!);
         }
 
         if (xmpProfile != null)
         {
             isVp8X = true;
             xmpBytes = xmpProfile.Data;
-            riffSize += MetadataChunkSize(xmpBytes);
+            riffSize += MetadataChunkSize(xmpBytes!);
         }
 
         if (iccProfile != null)