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First pass on ExifWriter spanification

af/merge-core
Jason Nelson 8 years ago
parent
1c1592b9d5
commit
291f5a5199
3 changed files with 82 additions and 41 deletions
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  1. 6
      src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs
  2. 2
      src/ImageSharp/MetaData/Profiles/Exif/ExifValue.cs
  3. 115
      src/ImageSharp/MetaData/Profiles/Exif/ExifWriter.cs

6
src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs
View File

@ -19,8 +19,6 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
/// </summary>
internal sealed class ExifReader
{
private delegate TDataType ConverterMethod<TDataType>(ReadOnlySpan<byte> data);
private readonly List<ExifTag> invalidTags = new List<ExifTag>();
private readonly byte[] exifData;
private int position;
@ -36,6 +34,8 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
this.exifData = exifData;
}
private delegate TDataType ConverterMethod<TDataType>(ReadOnlySpan<byte> data);
/// <summary>
/// Gets the invalid tags.
/// </summary>
@ -412,7 +412,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
}
span = new ReadOnlySpan<byte>(this.exifData, this.position, length);
this.position += length;
return true;

2
src/ImageSharp/MetaData/Profiles/Exif/ExifValue.cs
View File

@ -696,7 +696,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
{
return description;
}
switch (this.DataType)
{
case ExifDataType.Ascii:

115
src/ImageSharp/MetaData/Profiles/Exif/ExifWriter.cs
View File

@ -2,8 +2,8 @@
// Licensed under the Apache License, Version 2.0.
using System;
using System.Buffers.Binary;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Text;
using SixLabors.ImageSharp.Primitives;
@ -24,10 +24,10 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
/// </summary>
private ExifParts allowedParts;
private IList<ExifValue> values;
private IList<int> dataOffsets;
private IList<int> ifdIndexes;
private IList<int> exifIndexes;
private IList<int> gpsIndexes;
private List<int> dataOffsets;
private List<int> ifdIndexes;
private List<int> exifIndexes;
private List<int> gpsIndexes;
/// <summary>
/// Initializes a new instance of the <see cref="ExifWriter"/> class.
@ -89,6 +89,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
length += 10 + 4 + 2;
byte[] result = new byte[length];
result[0] = (byte)'E';
result[1] = (byte)'x';
result[2] = (byte)'i';
@ -114,9 +115,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
this.values[gpsIndex] = this.values[gpsIndex].WithValue(ifdOffset + ifdLength + exifLength);
}
i = Write(BitConverter.GetBytes(ifdOffset), result, i);
i = WriteUInt32(ifdOffset, result, i);
i = this.WriteHeaders(this.ifdIndexes, result, i);
i = Write(BitConverter.GetBytes(thumbnailOffset), result, i);
i = WriteUInt32(thumbnailOffset, result, i);
i = this.WriteData(this.ifdIndexes, result, i);
if (exifLength > 0)
@ -131,18 +132,60 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
i = this.WriteData(this.gpsIndexes, result, i);
}
Write(BitConverter.GetBytes((ushort)0), result, i);
WriteUInt16((ushort)0, result, i);
return result;
}
private static int Write(byte[] source, byte[] destination, int offset)
private static unsafe int WriteSingle(float value, Span<byte> destination, int offset)
{
BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(offset, 4), *((int*)&value));
return offset + 4;
}
private static unsafe int WriteDouble(double value, Span<byte> destination, int offset)
{
Buffer.BlockCopy(source, 0, destination, offset, source.Length);
BinaryPrimitives.WriteInt64LittleEndian(destination.Slice(offset, 8), *((long*)&value));
return offset + 8;
}
private static int Write(ReadOnlySpan<byte> source, Span<byte> destination, int offset)
{
source.CopyTo(destination.Slice(offset, source.Length));
return offset + source.Length;
}
private static int WriteInt16(short value, Span<byte> destination, int offset)
{
BinaryPrimitives.WriteInt16LittleEndian(destination.Slice(offset, 2), value);
return offset + 2;
}
private static int WriteUInt16(ushort value, Span<byte> destination, int offset)
{
BinaryPrimitives.WriteUInt16LittleEndian(destination.Slice(offset, 2), value);
return offset + 2;
}
private static int WriteUInt32(uint value, Span<byte> destination, int offset)
{
BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(offset, 4), value);
return offset + 4;
}
private static int WriteInt32(int value, Span<byte> destination, int offset)
{
BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(offset, 4), value);
return offset + 4;
}
private int GetIndex(IList<int> indexes, ExifTag tag)
{
foreach (int index in indexes)
@ -163,7 +206,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
{
if (((int)this.allowedParts & (int)part) == 0)
{
return new Collection<int>();
return new List<int>();
}
var result = new List<int>();
@ -223,7 +266,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
return newOffset;
}
private int WriteData(IList<int> indexes, byte[] destination, int offset)
private int WriteData(List<int> indexes, byte[] destination, int offset)
{
if (this.dataOffsets.Count == 0)
{
@ -238,7 +281,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
ExifValue value = this.values[index];
if (value.Length > 4)
{
Write(BitConverter.GetBytes(newOffset - StartIndex), destination, this.dataOffsets[i++]);
WriteUInt32((uint)(newOffset - StartIndex), destination, this.dataOffsets[i++]);
newOffset = this.WriteValue(value, destination, newOffset);
}
}
@ -246,11 +289,11 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
return newOffset;
}
private int WriteHeaders(IList<int> indexes, byte[] destination, int offset)
private int WriteHeaders(List<int> indexes, byte[] destination, int offset)
{
this.dataOffsets = new List<int>();
int newOffset = Write(BitConverter.GetBytes((ushort)indexes.Count), destination, offset);
int newOffset = WriteUInt16((ushort)indexes.Count, destination, offset);
if (indexes.Count == 0)
{
@ -260,9 +303,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
foreach (int index in indexes)
{
ExifValue value = this.values[index];
newOffset = Write(BitConverter.GetBytes((ushort)value.Tag), destination, newOffset);
newOffset = Write(BitConverter.GetBytes((ushort)value.DataType), destination, newOffset);
newOffset = Write(BitConverter.GetBytes((uint)value.NumberOfComponents), destination, newOffset);
newOffset = WriteUInt16((ushort)value.Tag, destination, newOffset);
newOffset = WriteUInt16((ushort)value.DataType, destination, newOffset);
newOffset = WriteUInt32((uint)value.NumberOfComponents, destination, newOffset);
if (value.Length > 4)
{
@ -279,23 +322,19 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
return newOffset;
}
private int WriteRational(in Rational value, byte[] destination, int offset)
private static void WriteRational(Span<byte> destination, in Rational value)
{
Write(BitConverter.GetBytes(value.Numerator), destination, offset);
Write(BitConverter.GetBytes(value.Denominator), destination, offset + 4);
return offset + 8;
BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(0, 4), value.Numerator);
BinaryPrimitives.WriteUInt32LittleEndian(destination.Slice(4, 4), value.Denominator);
}
private int WriteSignedRational(in SignedRational value, byte[] destination, int offset)
private static void WriteSignedRational(Span<byte> destination, in SignedRational value)
{
Write(BitConverter.GetBytes(value.Numerator), destination, offset);
Write(BitConverter.GetBytes(value.Denominator), destination, offset + 4);
return offset + 8;
BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(0, 4), value.Numerator);
BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(4, 4), value.Denominator);
}
private int WriteValue(ExifDataType dataType, object value, byte[] destination, int offset)
private int WriteValue(ExifDataType dataType, object value, Span<byte> destination, int offset)
{
switch (dataType)
{
@ -306,24 +345,26 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif
destination[offset] = (byte)value;
return offset + 1;
case ExifDataType.DoubleFloat:
return Write(BitConverter.GetBytes((double)value), destination, offset);
return WriteDouble((double)value, destination, offset);
case ExifDataType.Short:
return Write(BitConverter.GetBytes((ushort)value), destination, offset);
return WriteUInt16((ushort)value, destination, offset);
case ExifDataType.Long:
return Write(BitConverter.GetBytes((uint)value), destination, offset);
return WriteUInt32((uint)value, destination, offset);
case ExifDataType.Rational:
return this.WriteRational((Rational)value, destination, offset);
WriteRational(destination.Slice(offset, 8), (Rational)value);
return offset + 8;
case ExifDataType.SignedByte:
destination[offset] = unchecked((byte)((sbyte)value));
return offset + 1;
case ExifDataType.SignedLong:
return Write(BitConverter.GetBytes((int)value), destination, offset);
return WriteInt32((int)value, destination, offset);
case ExifDataType.SignedShort:
return Write(BitConverter.GetBytes((short)value), destination, offset);
return WriteInt16((short)value, destination, offset);
case ExifDataType.SignedRational:
return this.WriteSignedRational((SignedRational)value, destination, offset);
WriteSignedRational(destination.Slice(offset, 8), (SignedRational)value);
return offset + 8;
case ExifDataType.SingleFloat:
return Write(BitConverter.GetBytes((float)value), destination, offset);
return WriteSingle((float)value, destination, offset);
default:
throw new NotImplementedException();
}

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