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@ -12,70 +12,13 @@ using System.Text; |
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namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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{ |
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/// <summary>
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/// Reads and parses EXIF data from a stream.
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/// </summary>
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internal class ExifReader |
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internal class ExifReader : BaseExifReader |
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{ |
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private readonly Stream data; |
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private readonly byte[] offsetBuffer = new byte[4]; |
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private readonly byte[] buf4 = new byte[4]; |
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private readonly byte[] buf2 = new byte[2]; |
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// used for sequential read big values (actual for multiframe big files)
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// todo: different tags can link to the same data (stream offset) - investigate
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private readonly SortedList<uint, Action> lazyLoaders = new SortedList<uint, Action>(new DuplicateKeyComparer<uint>()); |
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private readonly List<Action> loaders = new List<Action>(); |
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private bool isBigEndian; |
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private List<ExifTag> invalidTags; |
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private uint exifOffset = 0; |
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private uint gpsOffset = 0; |
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public ExifReader(bool isBigEndian, Stream stream) |
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public ExifReader(byte[] exifData) |
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: base(new MemoryStream(exifData ?? throw new ArgumentNullException(nameof(exifData)))) |
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{ |
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this.isBigEndian = isBigEndian; |
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this.data = stream ?? throw new ArgumentNullException(nameof(stream)); |
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} |
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public ExifReader(byte[] exifData) => |
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this.data = new MemoryStream(exifData ?? throw new ArgumentNullException(nameof(exifData))); |
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private delegate TDataType ConverterMethod<TDataType>(ReadOnlySpan<byte> data); |
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/// <summary>
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/// Gets the invalid tags.
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/// </summary>
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public IReadOnlyList<ExifTag> InvalidTags => this.invalidTags ?? (IReadOnlyList<ExifTag>)Array.Empty<ExifTag>(); |
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/// <summary>
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/// Gets the thumbnail length in the byte stream.
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/// </summary>
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public uint ThumbnailLength { get; private set; } |
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/// <summary>
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/// Gets the thumbnail offset position in the byte stream.
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/// </summary>
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public uint ThumbnailOffset { get; private set; } |
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protected uint? LazyStartOffset => this.lazyLoaders.Count > 0 ? this.lazyLoaders.Keys[0] : (uint?)null; |
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private uint Length => (uint)this.data.Length; |
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private int RemainingLength |
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{ |
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get |
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{ |
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if (this.data.Position >= this.data.Length) |
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{ |
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return 0; |
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} |
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return (int)(this.data.Length - this.data.Position); |
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} |
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} |
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/// <summary>
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@ -84,12 +27,12 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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/// <returns>
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/// The <see cref="Collection{ExifValue}"/>.
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/// </returns>
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public virtual List<IExifValue> ReadValues() |
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public List<IExifValue> ReadValues() |
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{ |
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var values = new List<IExifValue>(); |
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// Exif header: II == 0x4949
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this.isBigEndian = this.ReadUInt16() != 0x4949; |
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// II == 0x4949
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this.IsBigEndian = this.ReadUInt16() != 0x4949; |
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if (this.ReadUInt16() != 0x002A) |
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{ |
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@ -97,38 +40,107 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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} |
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uint ifdOffset = this.ReadUInt32(); |
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this.AddValues(values, ifdOffset); |
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this.ReadValues(values, ifdOffset); |
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uint thumbnailOffset = this.ReadUInt32(); |
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this.GetThumbnail(thumbnailOffset); |
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this.AddSubIfdValues(values); |
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this.LazyLoad(); |
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this.ReadSubIfd(values); |
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foreach (Action loader in this.loaders) |
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{ |
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loader(); |
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} |
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return values; |
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} |
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protected void LazyLoad() |
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protected override void RegisterExtLoader(uint offset, Action loader) => this.loaders.Add(loader); |
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private void GetThumbnail(uint offset) |
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{ |
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foreach (Action act in this.lazyLoaders.Values) |
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if (offset == 0) |
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{ |
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return; |
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} |
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var values = new List<IExifValue>(); |
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this.ReadValues(values, offset); |
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foreach (ExifValue value in values) |
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{ |
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act(); |
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if (value == ExifTag.JPEGInterchangeFormat) |
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{ |
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this.ThumbnailOffset = ((ExifLong)value).Value; |
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} |
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else if (value == ExifTag.JPEGInterchangeFormatLength) |
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{ |
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this.ThumbnailLength = ((ExifLong)value).Value; |
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} |
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} |
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} |
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} |
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/// <summary>
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/// Reads and parses EXIF data from a stream.
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/// </summary>
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internal abstract class BaseExifReader |
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{ |
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private readonly byte[] offsetBuffer = new byte[4]; |
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private readonly byte[] buf4 = new byte[4]; |
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private readonly byte[] buf2 = new byte[2]; |
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private readonly Stream data; |
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private bool isBigEndian; |
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private List<ExifTag> invalidTags; |
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private uint exifOffset; |
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private uint gpsOffset; |
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protected BaseExifReader(Stream stream) => |
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this.data = stream ?? throw new ArgumentNullException(nameof(stream)); |
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private delegate TDataType ConverterMethod<TDataType>(ReadOnlySpan<byte> data); |
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/// <summary>
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/// Gets the invalid tags.
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/// </summary>
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public IReadOnlyList<ExifTag> InvalidTags => this.invalidTags ?? (IReadOnlyList<ExifTag>)Array.Empty<ExifTag>(); |
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/// <summary>
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/// Gets or sets the thumbnail length in the byte stream.
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/// </summary>
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public uint ThumbnailLength { get; protected set; } |
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/// <summary>
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/// Gets or sets the thumbnail offset position in the byte stream.
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/// </summary>
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public uint ThumbnailOffset { get; protected set; } |
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public bool IsBigEndian |
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{ |
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get => this.isBigEndian; |
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protected set => this.isBigEndian = value; |
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} |
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protected abstract void RegisterExtLoader(uint offset, Action loader); |
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/// <summary>
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/// Adds the collection of EXIF values to the reader.
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/// Reads the values to the values collection.
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/// </summary>
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/// <param name="values">The values.</param>
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/// <param name="index">The index.</param>
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protected void AddValues(List<IExifValue> values, uint index) |
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/// <param name="offset">The IFD offset.</param>
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protected void ReadValues(List<IExifValue> values, uint offset) |
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{ |
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if (index > this.Length) |
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if (offset > this.data.Length) |
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{ |
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return; |
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} |
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this.Seek(index); |
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this.Seek(offset); |
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int count = this.ReadUInt16(); |
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for (int i = 0; i < count; i++) |
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@ -137,16 +149,16 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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} |
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} |
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protected void AddSubIfdValues(List<IExifValue> values) |
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protected void ReadSubIfd(List<IExifValue> values) |
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{ |
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if (this.exifOffset != 0) |
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{ |
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this.AddValues(values, this.exifOffset); |
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this.ReadValues(values, this.exifOffset); |
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} |
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if (this.gpsOffset != 0) |
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{ |
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this.AddValues(values, this.gpsOffset); |
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this.ReadValues(values, this.gpsOffset); |
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} |
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} |
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@ -280,7 +292,7 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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{ |
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// 2 | 2 | 4 | 4
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// tag | type | count | value offset
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if (this.RemainingLength < 12) |
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if ((this.data.Length - this.data.Position) < 12) |
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{ |
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return; |
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} |
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@ -316,28 +328,22 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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uint size = numberOfComponents * ExifDataTypes.GetSize(dataType); |
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if (size > 4) |
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{ |
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uint newIndex = this.ConvertToUInt32(this.offsetBuffer); |
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uint newOffset = this.ConvertToUInt32(this.offsetBuffer); |
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// Ensure that the new index does not overrun the data
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if (newIndex > int.MaxValue || newIndex + size > this.Length) |
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if (newOffset > int.MaxValue || (newOffset + size) > this.data.Length) |
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{ |
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this.AddInvalidTag(new UnkownExifTag(tag)); |
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return; |
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} |
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if (this.lazyLoaders.ContainsKey(newIndex)) |
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{ |
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Debug.WriteLine($"Duplicate offset: tag={tag}, size={size}, offset={newIndex}"); |
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} |
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this.lazyLoaders.Add(newIndex, () => |
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this.RegisterExtLoader(newOffset, () => |
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{ |
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var dataBuffer = new byte[size]; |
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this.Seek(newIndex); |
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this.Seek(newOffset); |
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if (this.TryReadSpan(dataBuffer)) |
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{ |
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object value = this.ConvertValue(dataType, dataBuffer, numberOfComponents); |
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this.Add(values, exifValue, value); |
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} |
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}); |
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@ -391,7 +397,7 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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private bool TryReadSpan(Span<byte> span) |
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{ |
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int length = span.Length; |
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if (this.RemainingLength < length) |
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if ((this.data.Length - this.data.Position) < length) |
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{ |
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span = default; |
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return false; |
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@ -411,29 +417,6 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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? this.ConvertToShort(this.buf2) |
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: default; |
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private void GetThumbnail(uint offset) |
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{ |
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if (offset == 0) |
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{ |
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return; |
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} |
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var values = new List<IExifValue>(); |
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this.AddValues(values, offset); |
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foreach (ExifValue value in values) |
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{ |
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if (value == ExifTag.JPEGInterchangeFormat) |
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{ |
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this.ThumbnailOffset = ((ExifLong)value).Value; |
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} |
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else if (value == ExifTag.JPEGInterchangeFormatLength) |
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{ |
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this.ThumbnailLength = ((ExifLong)value).Value; |
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} |
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} |
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} |
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private double ConvertToDouble(ReadOnlySpan<byte> buffer) |
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{ |
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if (buffer.Length < 8) |
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@ -538,19 +521,5 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif |
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? BinaryPrimitives.ReadInt16BigEndian(buffer) |
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: BinaryPrimitives.ReadInt16LittleEndian(buffer); |
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} |
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/// <summary><see cref="DuplicateKeyComparer{TKey}"/> used for possiblity add a duplicate offsets (but tags don't duplicate).</summary>
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/// <typeparam name="TKey">The type of the key.</typeparam>
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public class DuplicateKeyComparer<TKey> : IComparer<TKey> |
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where TKey : IComparable |
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{ |
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public int Compare(TKey x, TKey y) |
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{ |
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int result = x.CompareTo(y); |
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// Handle equality as beeing greater
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return (result == 0) ? 1 : result; |
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} |
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} |
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} |
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} |
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Ildar Khayrutdinov
5 years ago