Field Detail

• SIGNATURE_LEN

  protected static final int SIGNATURE_LEN

  See Also:

  Constant Field Values

• withSignature

  protected final boolean withSignature

Constructor Detail

• ChunkSeqReader

  public ChunkSeqReader()

  Creates a ChunkSeqReader (with signature)

• ChunkSeqReader

  public ChunkSeqReader(boolean withSignature)

  Parameters:

  withSignature - If true, the stream is assumed be prepended by 8 bit signature

Method Detail

• consume

  public int consume(byte[] buffer,
            int offset,
            int len)

  Consumes (in general, partially) a number of bytes. A single call never involves more than one chunk. When the signature is read, it calls checkSignature() When the start of a chunk is detected, it calls startNewChunk(int, String, long) When data from a chunk is being read, it delegates to ChunkReader.feedBytes(byte[], int, int) The caller might want to call this method more than once in succesion This should rarely be overriden

  Specified by:

  consume in interface IBytesConsumer

  Parameters:

  buffer -

  offset - Offset in buffer

  len - Valid bytes that can be consumed

  Returns:

  processed bytes, in the 1-len range. -1 if done. Only returns 0 if len=0.

• feedAll

  public boolean feedAll(byte[] buf,
                int off,
                int len)

  Trys to feeds exactly len bytes, calling consume(byte[], int, int) retrying if necessary. This should only be used in callback mode

  Returns:

  true if succceded

• startNewChunk

  protected void startNewChunk(int len,
                   String id,
                   long offset)

  Called when a chunk start has been read (id and length), before the chunk data itself is read. It creates a new ChunkReader (field accesible via getCurChunkReader()) in the corresponding mode, and eventually a curReaderDeflatedSet.(field accesible via getCurReaderDeflatedSet()) To decide the mode and options, it calls shouldCheckCrc(int, String), shouldSkipContent(int, String), isIdatKind(String). Those methods should be overriden in preference to this. The respective ChunkReader.chunkDone() method is directed to this postProcessChunk(ChunkReader).

• postProcessChunk

  protected void postProcessChunk(ChunkReader chunkR)

  This is called after a chunk is read, in all modes. This implementation only chenks the id of the first chunk, and process the IEND chunk (sets done=true) Further processing should be overriden (call this first!)

• createIdatSet

  protected DeflatedChunksSet createIdatSet(String id)

  DeflatedChunksSet factory. This implementation is quite dummy, it usually should be overriden.

• isIdatKind

  protected boolean isIdatKind(String id)

  Decides if this Chunk is of "IDAT" kind (in concrete: if it is, and if it's not to be skiped, a DeflatedChunksSet will be created to deflate it and process+ the deflated data) This implementation return false.

  Parameters:

  id -

• shouldSkipContent

  protected boolean shouldSkipContent(int len,
                          String id)

  Chunks can be skipped depending on id and/or length. Skipped chunks are still processed, but their data will be null, and CRC will never checked

  Parameters:

  len -

  id -

• shouldCheckCrc

  protected boolean shouldCheckCrc(int len,
                       String id)

• checkSignature

  protected void checkSignature(byte[] buf)

  Throws PngjInputException if bad signature

  Parameters:

  buf - Signature. Should be of length 8

• isSignatureDone

  public boolean isSignatureDone()

  If false, we are still reading the signature

  Returns:

  true if signature has been read (or if we don't have signature)

• isDone

  public boolean isDone()

  If true, we either have processe the IEND chunk, or close() has been called, or a fatal error has happened

• getBytesCount

  public long getBytesCount()

  total of bytes read (buffered or not)

• getChunkCount

  public int getChunkCount()

  Returns:

  Chunks already read, including partial reading (currently reading)

• getCurChunkReader

  public ChunkReader getCurChunkReader()

  Currently reading chunk, or just ended reading

  Returns:

  null only if still reading signature

• getCurReaderDeflatedSet

  public DeflatedChunksSet getCurReaderDeflatedSet()

  The current deflated set (typically IDAT chunks) reader. This is not null only while reading that set. Notice that there could be several idat sets (eg for APNG)

• close

  public void close()

  Forces a closing (abort)

• isAtChunkBoundary

  public boolean isAtChunkBoundary()

  Returns true if we are not in middle of a chunk: we have just ended reading past chunk , or we are at the start, or end of signature, or we are done

• firstChunkId

  protected String firstChunkId()

  Which should be the id of the first chunk

  Returns:

  null if you don't want to check it

• endChunkId

  protected String endChunkId()

  Which should be the id of the last chunk

  Returns:

  "IEND"