public IReadOnlyList <IGraphicsStateOperation> Parse(int pageNumber, IInputBytes inputBytes,
ILog log)
{
var scanner = new CoreTokenScanner(inputBytes);
var precedingTokens = new List <IToken>();
var graphicsStateOperations = new List <IGraphicsStateOperation>();
var lastEndImageOffset = new long?();
while (scanner.MoveNext())
{
var token = scanner.CurrentToken;
if (token is InlineImageDataToken inlineImageData)
{
var dictionary = new Dictionary <NameToken, IToken>();
for (var i = 0; i < precedingTokens.Count - 1; i++)
{
var t = precedingTokens[i];
if (!(t is NameToken n))
{
continue;
}
i++;
dictionary[n] = precedingTokens[i];
}
graphicsStateOperations.Add(new BeginInlineImageData(dictionary));
graphicsStateOperations.Add(new EndInlineImage(inlineImageData.Data));
lastEndImageOffset = scanner.CurrentPosition - 2;
precedingTokens.Clear();
}
else if (token is OperatorToken op)
{
// Handle an end image where the stream of image data contained EI but was not actually a real end image operator.
if (op.Data == "EI")
{
// Check an end image operation was the last thing that happened.
IGraphicsStateOperation lastOperation = graphicsStateOperations.Count > 0
? graphicsStateOperations[graphicsStateOperations.Count - 1]
: null;
if (lastEndImageOffset == null || lastOperation == null || !(lastOperation is EndInlineImage lastEndImage))
{
throw new PdfDocumentFormatException("Encountered End Image token outside an inline image on " +
$"page {pageNumber} at offset in content: {scanner.CurrentPosition}.");
}
// Work out how much data we missed between the false EI operator and the actual one.
var actualEndImageOffset = scanner.CurrentPosition - 3;
log.Warn($"End inline image (EI) encountered after previous EI, attempting recovery at {actualEndImageOffset}.");
var gap = (int)(actualEndImageOffset - lastEndImageOffset);
var from = inputBytes.CurrentOffset;
inputBytes.Seek(lastEndImageOffset.Value);
// Recover the full image data.
{
var missingData = new byte[gap];
var read = inputBytes.Read(missingData);
if (read != gap)
{
throw new InvalidOperationException($"Failed to read expected buffer length {gap} on page {pageNumber} " +
$"when reading inline image at offset in content: {lastEndImageOffset.Value}.");
}
// Replace the last end image operator with one containing the full set of data.
graphicsStateOperations.Remove(lastEndImage);
graphicsStateOperations.Add(new EndInlineImage(lastEndImage.ImageData.Concat(missingData).ToArray()));
}
lastEndImageOffset = actualEndImageOffset;
inputBytes.Seek(from);
}
else
{
IGraphicsStateOperation operation;
try
{
operation = operationFactory.Create(op, precedingTokens);
}
catch (Exception ex)
{
// End images can cause weird state if the "EI" appears inside the inline data stream.
if (TryGetLastEndImage(graphicsStateOperations, out _, out _))
{
log.Error($"Failed reading an operation at offset {inputBytes.CurrentOffset} for page {pageNumber}.", ex);
operation = null;
}
else
{
throw;
}
}
if (operation != null)
{
graphicsStateOperations.Add(operation);
}
else if (graphicsStateOperations.Count > 0)
{
if (TryGetLastEndImage(graphicsStateOperations, out var prevEndInlineImage, out var index) && lastEndImageOffset.HasValue)
{
log.Warn($"Operator {op.Data} was not understood following end of inline image data at {lastEndImageOffset}, " +
"attempting recovery.");
var nextByteSet = scanner.RecoverFromIncorrectEndImage(lastEndImageOffset.Value);
graphicsStateOperations.RemoveRange(index, graphicsStateOperations.Count - index);
var newEndInlineImage = new EndInlineImage(prevEndInlineImage.ImageData.Concat(nextByteSet).ToList());
graphicsStateOperations.Add(newEndInlineImage);
lastEndImageOffset = scanner.CurrentPosition - 3;
}
else
{
log.Warn($"Operator which was not understood encountered. Values was {op.Data}. Ignoring.");
}
}
}
precedingTokens.Clear();
}
public void Add(IGraphicsStateOperation operation)
{
throw new NotSupportedException("Writing to a copied content stream is not supported.");
}
public IReadOnlyList <IGraphicsStateOperation> Parse(int pageNumber, IInputBytes inputBytes)
{
var scanner = new CoreTokenScanner(inputBytes);
var precedingTokens = new List <IToken>();
var graphicsStateOperations = new List <IGraphicsStateOperation>();
var lastEndImageOffset = new long?();
while (scanner.MoveNext())
{
var token = scanner.CurrentToken;
if (token is InlineImageDataToken inlineImageData)
{
var dictionary = new Dictionary <NameToken, IToken>();
for (var i = 0; i < precedingTokens.Count - 1; i++)
{
var t = precedingTokens[i];
if (!(t is NameToken n))
{
continue;
}
i++;
dictionary[n] = precedingTokens[i];
}
graphicsStateOperations.Add(new BeginInlineImageData(dictionary));
graphicsStateOperations.Add(new EndInlineImage(inlineImageData.Data));
lastEndImageOffset = scanner.CurrentPosition - 2;
precedingTokens.Clear();
}
else if (token is OperatorToken op)
{
// Handle an end image where the stream of image data contained EI but was not actually a real end image operator.
if (op.Data == "EI")
{
// Check an end image operation was the last thing that happened.
IGraphicsStateOperation lastOperation = graphicsStateOperations.Count > 0
? graphicsStateOperations[graphicsStateOperations.Count - 1]
: null;
if (lastEndImageOffset == null || lastOperation == null || !(lastOperation is EndInlineImage lastEndImage))
{
throw new PdfDocumentFormatException("Encountered End Image token outside an inline image on " +
$"page {pageNumber} at offset in content: {scanner.CurrentPosition}.");
}
// Work out how much data we missed between the false EI operator and the actual one.
var actualEndImageOffset = scanner.CurrentPosition - 3;
var gap = (int)(actualEndImageOffset - lastEndImageOffset);
var from = inputBytes.CurrentOffset;
inputBytes.Seek(lastEndImageOffset.Value);
// Recover the full image data.
{
var missingData = new byte[gap];
var read = inputBytes.Read(missingData);
if (read != gap)
{
throw new InvalidOperationException($"Failed to read expected buffer length {gap} on page {pageNumber} " +
$"when reading inline image at offset in content: {lastEndImageOffset.Value}.");
}
// Replace the last end image operator with one containing the full set of data.
graphicsStateOperations.Remove(lastEndImage);
graphicsStateOperations.Add(new EndInlineImage(lastEndImage.ImageData.Concat(missingData).ToArray()));
}
lastEndImageOffset = actualEndImageOffset;
inputBytes.Seek(from);
}
else
{
var operation = operationFactory.Create(op, precedingTokens);
if (operation != null)
{
graphicsStateOperations.Add(operation);
}
}
precedingTokens.Clear();
}
else if (token is CommentToken)
{
}
else
{
precedingTokens.Add(token);
}
}
return(graphicsStateOperations);
}
public void Add(IGraphicsStateOperation operation)
{
operations.Add(operation);
}
internal void Add(IGraphicsStateOperation newOperation)
{
Operations.Add(newOperation);
}
