private static async Task CopyStrippedImageAsync(TiffFileContentReader contentReader, TiffTagReader tagReader, TiffImageFileDirectoryWriter dest, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
TiffValueCollection <ulong> offsets = await tagReader.ReadStripOffsetsAsync(cancellationToken);
TiffValueCollection <ulong> byteCounts = await tagReader.ReadStripByteCountsAsync(cancellationToken);
if (offsets.Count != byteCounts.Count)
{
throw new InvalidDataException("Failed to copy stripped image data. StripOffsets and StripByteCounts don't have the same amount of elements.");
}
uint[] offsets32 = new uint[offsets.Count];
uint[] byteCounts32 = new uint[offsets.Count];
byte[]? buffer = null;
try
{
for (int i = 0; i < offsets.Count; i++)
{
int offset = checked ((int)offsets[i]);
int byteCount = checked ((int)byteCounts[i]);
byteCounts32[i] = checked ((uint)byteCount);
if (buffer is null || byteCount > buffer.Length)
{
if (!(buffer is null))
{
ArrayPool <byte> .Shared.Return(buffer);
}
buffer = ArrayPool <byte> .Shared.Rent(byteCount);
}
if (await contentReader.ReadAsync(offset, new ArraySegment <byte>(buffer, 0, byteCount), cancellationToken) != byteCount)
{
throw new InvalidDataException("Invalid ByteCount field.");
}
TiffStreamOffset region = await dest.FileWriter.WriteAlignedBytesAsync(buffer, 0, byteCount);
offsets32[i] = checked ((uint)region.Offset);
}
}
finally
{
if (!(buffer is null))
{
ArrayPool <byte> .Shared.Return(buffer);
}
}
await dest.WriteTagAsync(TiffTag.StripOffsets, TiffValueCollection.UnsafeWrap(offsets32));
await dest.WriteTagAsync(TiffTag.StripByteCounts, TiffValueCollection.UnsafeWrap(byteCounts32));
}
public async ValueTask InvokeAsync(TiffImageDecoderContext context, ITiffImageDecoderPipelineNode next)
{
MemoryPool <byte> memoryPool = context.MemoryPool ?? MemoryPool <byte> .Shared;
TiffFileContentReader contentReader = context.ContentReader ?? throw new InvalidOperationException();
IMemoryOwner <byte>?dataHandle = null;
Memory <byte> data;
try
{
const int BufferSize = 65536;
using (var bufferWriter = new MemoryPoolBufferWriter(memoryPool))
{
// Read JPEG stream
TiffStreamRegion streamRegion = _streamRegion;
do
{
int readSize = Math.Min(streamRegion.Length, BufferSize);
Memory <byte> memory = bufferWriter.GetMemory(readSize);
memory = memory.Slice(0, Math.Min(streamRegion.Length, memory.Length));
readSize = await contentReader.ReadAsync(streamRegion.Offset, memory, context.CancellationToken).ConfigureAwait(false);
bufferWriter.Advance(readSize);
streamRegion = new TiffStreamRegion(streamRegion.Offset + readSize, streamRegion.Length - readSize);
} while (streamRegion.Length > 0);
// Identify the image
var decoder = new JpegDecoder();
decoder.MemoryPool = memoryPool;
decoder.SetInput(bufferWriter.GetReadOnlySequence());
decoder.Identify();
if (decoder.Width != context.SourceImageSize.Width || decoder.Height != context.SourceImageSize.Height)
{
throw new InvalidOperationException("The image size does not match.");
}
if (decoder.Precision != 8)
{
throw new InvalidOperationException("Only 8-bit JPEG is supported.");
}
// Adjust buffer size and reading region to reduce buffer size
int skippedWidth = context.SourceReadOffset.X / 8 * 8;
int skippedHeight = context.SourceReadOffset.Y / 8 * 8;
context.SourceReadOffset = new TiffPoint(context.SourceReadOffset.X % 8, context.SourceReadOffset.Y % 8);
int bufferWidth = context.SourceReadOffset.X + context.ReadSize.Width;
int bufferHeight = context.SourceReadOffset.Y + context.ReadSize.Height;
context.SourceImageSize = new TiffSize(bufferWidth, bufferHeight);
// Allocate buffer and decode image
int dataSize = bufferWidth * bufferHeight * decoder.NumberOfComponents;
dataHandle = memoryPool.Rent(dataSize);
data = dataHandle.Memory.Slice(0, dataSize);
decoder.SetOutputWriter(new LegacyJpegBufferOutputWriter(skippedWidth, bufferWidth, skippedHeight, bufferHeight, decoder.NumberOfComponents, data));
decoder.Decode();
}
// Pass the buffer to the next middleware
context.UncompressedData = data;
await next.RunAsync(context).ConfigureAwait(false);
context.UncompressedData = null;
}
finally
{
dataHandle?.Dispose();
}
}
public async Task TestRead(byte[] referenceContent, TiffFileContentSource source)
{
var rand = new Random(42);
try
{
TiffFileContentReader reader = await source.OpenReaderAsync();
// Random read within the range of the file.
for (int i = 0; i < 100; i++)
{
int offset = rand.Next(0, referenceContent.Length);
int count = 1;
if (offset + 1 < referenceContent.Length)
{
count = rand.Next(1, referenceContent.Length - offset);
}
await AssertReadAsync(reader, offset, count, count);
}
// Read on the edge of the file
await AssertReadAsync(reader, referenceContent.Length - 2048, 4096, 2048);
// Read past the end of the file.
await AssertReadAsync(reader, referenceContent.Length, 4096, 0);
await AssertReadAsync(reader, referenceContent.Length + 2048, 4096, 0);
}
finally
{
await source.DisposeAsync();
}
async Task AssertReadAsync(TiffFileContentReader reader, int fileOffset, int count, int expectedCount)
{
int readCount;
byte[] buffer = ArrayPool <byte> .Shared.Rent(count);
try
{
// Use Memory API
Array.Clear(buffer, 0, count);
readCount = await reader.ReadAsync(fileOffset, new Memory <byte>(buffer, 0, count), CancellationToken.None);
Assert.Equal(expectedCount, readCount);
Assert.True(buffer.AsSpan(0, readCount).SequenceEqual(referenceContent.AsSpan(Math.Min(referenceContent.Length, fileOffset), expectedCount)));
// Use ArraySegment API
Array.Clear(buffer, 0, count);
readCount = await reader.ReadAsync(fileOffset, new ArraySegment <byte>(buffer, 0, count), CancellationToken.None);
Assert.Equal(expectedCount, readCount);
Assert.True(buffer.AsSpan(0, readCount).SequenceEqual(referenceContent.AsSpan(Math.Min(referenceContent.Length, fileOffset), expectedCount)));
}
finally
{
ArrayPool <byte> .Shared.Return(buffer);
}
}
}