Package org.apache.pdfbox.pdmodel.graphics.image

Class PNGConverter

java.lang.Object

org.apache.pdfbox.pdmodel.graphics.image.PNGConverter

final class PNGConverter
extends java.lang.Object

This factory tries to encode a PNG given as byte array into a PDImageXObject by directly coping the image data into the PDF streams without decoding/encoding and re-compressing the PNG data.

If this is for any reason not possible, the factory will return null. You must then encode the image by loading it and using the LosslessFactory.

The W3C PNG spec was used to implement this class: https://www.w3.org/TR/2003/REC-PNG-20031110

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	PNGConverter.Chunk	Holds the information about a chunks
private static class	PNGConverter.MultipleInputStream
(package private) static class	PNGConverter.PNGConverterState	Holds all relevant chunks of the PNG

Field Summary

Fields

Modifier and Type	Field	Description
private static int	CHUNK_CHRM
private static int	CHUNK_GAMA
private static int	CHUNK_HIST
private static int	CHUNK_ICCP
private static int	CHUNK_IDAT
private static int	CHUNK_IEND
private static int	CHUNK_IHDR
private static int	CHUNK_ITXT
private static int	CHUNK_KBKG
private static int	CHUNK_PHYS
private static int	CHUNK_PLTE
private static int	CHUNK_SBIT
private static int	CHUNK_SPLT
private static int	CHUNK_SRGB
private static int	CHUNK_TEXT
private static int	CHUNK_TIME
private static int	CHUNK_TRNS
private static int	CHUNK_ZTXT
private static int[]	CRC_TABLE
private static org.apache.commons.logging.Log	LOG

Constructor Summary

Constructors

Modifier	Constructor	Description
private	PNGConverter()

Method Summary

Modifier and Type	Method	Description
private static COSDictionary	buildDecodeParams(PNGConverter.PNGConverterState state, PDColorSpace colorSpace)
private static PDImageXObject	buildImageObject(PDDocument document, PNGConverter.PNGConverterState state)	Build the base image object from the IDATs and profile information
private static PDImageXObject	buildIndexImage(PDDocument doc, PNGConverter.PNGConverterState state)	Build a indexed image
private static PDImageXObject	buildTransparencyMaskFromIndexedData(PDDocument doc, PDImageXObject image, PNGConverter.PNGConverterState state)
(package private) static boolean	checkChunkSane(PNGConverter.Chunk chunk)	Check if the chunk is sane, i.e.
(package private) static boolean	checkConverterState(PNGConverter.PNGConverterState state)	Check if the converter state is sane.
private static PDImageXObject	convertPng(PDDocument doc, PNGConverter.PNGConverterState state)	Convert the image using the state.
(package private) static PDImageXObject	convertPNGImage(PDDocument doc, byte[] imageData)	Try to convert a PNG into a PDImageXObject.
(package private) static int	crc(byte[] buf, int offset, int len)
private static COSStream	createCOSStreamwithIccProfile(PDDocument document, PDColorSpace colorSpace, PNGConverter.PNGConverterState state)
private static java.io.InputStream	getIDATInputStream(PNGConverter.PNGConverterState state)	Build an input stream for the IDAT data.
private static void	makeCrcTable()
(package private) static COSName	mapPNGRenderIntent(int renderIntent)	Map the renderIntent int to a PDF render intent.
private static PNGConverter.PNGConverterState	parsePNGChunks(byte[] imageData)	Parse the PNG structure into the PNGConverterState.
private static int	readInt(byte[] data, int offset)
private static float	readPNGFloat(byte[] bytes, int offset)
private static void	setupIndexedColorSpace(PDDocument doc, PNGConverter.Chunk lookupTable, PDImageXObject image, int highVal)
private static int	updateCrc(byte[] buf, int offset, int len)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final org.apache.commons.logging.Log LOG

CHUNK_IHDR

private static final int CHUNK_IHDR

See Also:

Constant Field Values

CHUNK_IDAT

private static final int CHUNK_IDAT

See Also:

Constant Field Values

CHUNK_PLTE

private static final int CHUNK_PLTE

See Also:

Constant Field Values

CHUNK_IEND

private static final int CHUNK_IEND

See Also:

Constant Field Values

CHUNK_TRNS

private static final int CHUNK_TRNS

See Also:

Constant Field Values

CHUNK_CHRM

private static final int CHUNK_CHRM

See Also:

Constant Field Values

CHUNK_GAMA

private static final int CHUNK_GAMA

See Also:

Constant Field Values

CHUNK_ICCP

private static final int CHUNK_ICCP

See Also:

Constant Field Values

CHUNK_SBIT

private static final int CHUNK_SBIT

See Also:

Constant Field Values

CHUNK_SRGB

private static final int CHUNK_SRGB

See Also:

Constant Field Values

CHUNK_TEXT

private static final int CHUNK_TEXT

See Also:

Constant Field Values

CHUNK_ZTXT

private static final int CHUNK_ZTXT

See Also:

Constant Field Values

CHUNK_ITXT

private static final int CHUNK_ITXT

See Also:

Constant Field Values

CHUNK_KBKG

private static final int CHUNK_KBKG

See Also:

Constant Field Values

CHUNK_HIST

private static final int CHUNK_HIST

See Also:

Constant Field Values

CHUNK_PHYS

private static final int CHUNK_PHYS

See Also:

Constant Field Values

CHUNK_SPLT

private static final int CHUNK_SPLT

See Also:

Constant Field Values

CHUNK_TIME

private static final int CHUNK_TIME

See Also:

Constant Field Values

CRC_TABLE

private static final int[] CRC_TABLE

Constructor Detail

PNGConverter

private PNGConverter()

Method Detail

convertPNGImage

static PDImageXObject convertPNGImage(PDDocument doc,
                                      byte[] imageData)
                               throws java.io.IOException

Try to convert a PNG into a PDImageXObject. If for any reason the PNG can not be converted, null is returned.

This usually means the PNG structure is damaged (CRC error, etc.) or it uses some features which can not be mapped to PDF.

Parameters:

doc - the document to put the image in

imageData - the byte data of the PNG

Returns:

null or the PDImageXObject built from the png

Throws:

java.io.IOException

convertPng

private static PDImageXObject convertPng(PDDocument doc,
                                         PNGConverter.PNGConverterState state)
                                  throws java.io.IOException

Convert the image using the state.

Parameters:

doc - the document to put the image in

state - the parser state containing the PNG chunks.

Returns:

null or the converted image

Throws:

java.io.IOException

buildIndexImage

private static PDImageXObject buildIndexImage(PDDocument doc,
                                              PNGConverter.PNGConverterState state)
                                       throws java.io.IOException

Build a indexed image

Throws:

java.io.IOException

buildTransparencyMaskFromIndexedData

private static PDImageXObject buildTransparencyMaskFromIndexedData(PDDocument doc,
                                                                   PDImageXObject image,
                                                                   PNGConverter.PNGConverterState state)
                                                            throws java.io.IOException

Throws:

java.io.IOException

setupIndexedColorSpace

private static void setupIndexedColorSpace(PDDocument doc,
                                           PNGConverter.Chunk lookupTable,
                                           PDImageXObject image,
                                           int highVal)
                                    throws java.io.IOException

Throws:

java.io.IOException

buildImageObject

private static PDImageXObject buildImageObject(PDDocument document,
                                               PNGConverter.PNGConverterState state)
                                        throws java.io.IOException

Build the base image object from the IDATs and profile information

Throws:

java.io.IOException

createCOSStreamwithIccProfile

private static COSStream createCOSStreamwithIccProfile(PDDocument document,
                                                       PDColorSpace colorSpace,
                                                       PNGConverter.PNGConverterState state)
                                                throws java.io.IOException

Throws:

java.io.IOException

buildDecodeParams

private static COSDictionary buildDecodeParams(PNGConverter.PNGConverterState state,
                                               PDColorSpace colorSpace)

getIDATInputStream

private static java.io.InputStream getIDATInputStream(PNGConverter.PNGConverterState state)

Build an input stream for the IDAT data. May need to concat multiple IDAT chunks.

Parameters:

state - the converter state.

Returns:

a input stream with the IDAT data.

mapPNGRenderIntent

static COSName mapPNGRenderIntent(int renderIntent)

Map the renderIntent int to a PDF render intent. See also https://www.w3.org/TR/2003/REC-PNG-20031110/#11sRGB

Parameters:

renderIntent - the PNG render intent

Returns:

the matching PDF Render Intent or null

checkConverterState

static boolean checkConverterState(PNGConverter.PNGConverterState state)

Check if the converter state is sane.

Parameters:

state - the parsed converter state

Returns:

true if the state seems plausible

checkChunkSane

static boolean checkChunkSane(PNGConverter.Chunk chunk)

Check if the chunk is sane, i.e. CRC matches and offsets and lengths in the byte array

readInt

private static int readInt(byte[] data,
                           int offset)

readPNGFloat

private static float readPNGFloat(byte[] bytes,
                                  int offset)

parsePNGChunks

private static PNGConverter.PNGConverterState parsePNGChunks(byte[] imageData)

Parse the PNG structure into the PNGConverterState. If we can't handle something, this method will return null.

Parameters:

imageData - the byte array with the PNG data

Returns:

null or the converter state with all relevant chunks

makeCrcTable

private static void makeCrcTable()

updateCrc

private static int updateCrc(byte[] buf,
                             int offset,
                             int len)

crc

static int crc(byte[] buf,
               int offset,
               int len)