Package ar.com.hjg.pngj

• Interface Summary 

  Interface	Description
  IBytesConsumer	Bytes consumer.
  IChunkFactory	Factory to create a PngChunk from a ChunkRaw.
  IImageLine	General format-translated image line.
  IImageLineArray	This interface is just for the sake of unifying some methods of ImageLineHelper that can use both ImageLineInt or ImageLineByte.
  IImageLineFactory<T extends IImageLine>	Image Line factory.
  IImageLineSet<T extends IImageLine>	Set of IImageLine elements.
  IImageLineSetFactory<T extends IImageLine>	Factory of IImageLineSet, used by PngReader.
  IPngWriterFactory

• Class Summary 

  Class	Description
  BufferedStreamFeeder	Reads bytes from an input stream, and feeds a IBytesConsumer.
  ChunkReader	Parses a PNG chunk, consuming bytes in one mode: ChunkReader.ChunkReaderMode.BUFFER, ChunkReader.ChunkReaderMode.PROCESS, ChunkReader.ChunkReaderMode.SKIP.
  ChunkSeqBuffering	This loads the png as a plain sequence of chunks, buffering all Useful to do things like insert or delete a ancilllary chunk.
  ChunkSeqReader	Consumes a stream of bytes that consist of a series of PNG-like chunks.
  ChunkSeqReaderPng	Adds to ChunkSeqReader the storing of PngChunk, with a PngFactory, and imageInfo + deinterlacer.
  ChunkSeqSkipping	This simple reader skips all chunks contents and stores the chunkRaw in a list.
  DeflatedChunkReader	Specialization of ChunkReader, for IDAT-like chunks.
  DeflatedChunksSet	A set of IDAT-like chunks which, concatenated, form a zlib stream.
  Deinterlacer
  IDatChunkWriter	Outputs a sequence of IDAT-like chunk, that is filled progressively until the max chunk length is reached (or until flush())
  IdatSet	This object process the concatenation of IDAT chunks.
  ImageInfo	Simple immutable wrapper for basic image info.
  ImageLineByte	Lightweight wrapper for an image scanline, used for read and write.
  ImageLineHelper	Bunch of utility static methods to proces an image line at the pixel level.
  ImageLineInt	Represents an image line, integer format (one integer by sample).
  ImageLineSetDefault<T extends IImageLine>	Default implementation of IImageLineSet.
  PngHelperInternal	Some utility static methods for internal use.
  PngReader	Reads a PNG image (pixels and/or metadata) from a file or stream.
  PngReaderApng
  PngReaderByte	Trivial extension of PngReader that uses ImageLineByte
  PngReaderFilter	This class allows to use a simple PNG reader as an input filter, wrapping a ChunkSeqReaderPng in callback mode.
  PngReaderInt	Trivial extension of PngReader that uses ImageLineInt.
  PngWriter	Writes a PNG image, line by line.
  PngWriterHc	Pngwriter with High compression EXPERIMENTAL

• Enum Summary 

  Enum	Description
  ChunkReader.ChunkReaderMode	Modes of ChunkReader chunk processing.
  FilterType	Internal PNG predictor filter type Negative values are pseudo types, actually global strategies for writing, that (can) result on different real filters for different rows

• Exception Summary 

  Exception	Description
  PngjBadCrcException	Exception thrown by bad CRC check
  PngjException	Generic exception for this library.
  PngjExceptionInternal	Exception for anomalous internal problems (sort of asserts) that point to some issue with the library
  PngjInputException	Exception thrown when reading a PNG.
  PngjOutputException	Exception thrown by writing process
  PngjUnsupportedException	Exception thrown because of some valid feature of PNG standard that this library does not support.

Package ar.com.hjg.pngj Description

  public static void convert(String origFilename, String destFilename) {
    // you can also use PngReader (esentially the same) or PngReaderByte 
    PngReaderInt pngr = new PngReaderInt(new File(origFilename));  
    System.out.println(pngr.toString());
    int channels = pngr.imgInfo.channels;
    if (channels < 3 || pngr.imgInfo.bitDepth != 8)
       throw new RuntimeException("For simplicity this supports only RGB8/RGBA8 images");
    // writer with same image properties as original
    PngWriter pngw = new PngWriter(new File(destFilename), pngr.imgInfo, true);
    // instruct the writer to grab all ancillary chunks from the original
    pngw.copyChunksFrom(pngr.getChunksList(), ChunkCopyBehaviour.COPY_ALL_SAFE);
    // add a textual chunk to writer
    pngw.getMetadata().setText(PngChunkTextVar.KEY_Description, "Decreased red and increased green");
    // also: while(pngr.hasMoreRows())
    for (int row = 0; row < pngr.imgInfo.rows; row++) {  
       ImageLineInt l1 = pngr.readRowInt(); // each element is a sample
       int[] scanline = l1.getScanline(); // to save typing
       for (int j = 0; j < pngr.imgInfo.cols; j++) {
          scanline[j * channels] /= 2;
          scanline[j * channels + 1] = ImageLineHelper.clampTo_0_255(scanline[j * channels + 1] + 20);
       }
       pngw.writeRow(l1);
    }
    pngr.end(); // it's recommended to end the reader first, in case there are trailing chunks to read
    pngw.end();
 }