ch.randelshofer.media.pbm
Class PBMDecoder

java.lang.Object
  ch.randelshofer.media.pbm.PBMDecoder

All Implemented Interfaces:

IFFVisitor

public class PBMDecoder
extends java.lang.Object
implements IFFVisitor

Creates Image objects by reading an IFF PBM stream.

PBM regular expression

 PBM ::= "FORM" #{ "PBM" BMHD [CMAP] [GRAB] [DEST] [SPRT] [CAMG] CRNG* CCRT* [BODY] }

 BMHD ::= "BMHD" #{ BitMapHeader }
 CMAP ::= "CMAP" #{ (red green blue)* } [0]
 GRAB ::= "GRAB" #{ Point2D }
 DEST ::= "DEST" #{ DestMerge }
 SPRT ::= "SPRT" #{ SpritePrecedence }
 CAMG ::= "CAMG" #{ LONG }

 CRNG ::= "CRNG" #{ CRange }
 CCRT ::= "CCRT" #{ CycleInfo }
 BODY ::= "BODY" #{ UBYTE* } [0]
 

The token "#" represents a ckSize LONG count of the following braced data bytes. E.g., a BMHD's "#" should equal sizeof(BitMapHeader). Literal strings are shown in "quotes", [square bracket items] are optional, and "*" means 0 or more repetitions. A sometimes-needed pad byte is shown as "[0]".

Version:

1.6 2010-08-02 Added support for CRNG and DRNG chunks.
1.5.1 2010-07-03 Improved performance of byterun1 decoder.
1.0 2005-04-05 Created.

Author:

Werner Randelshofer, Hausmatt 10, CH-6405 Immensee, Switzerland

Field Summary

protected static int	BMHD_ID
protected int	bmhdCompression
protected int	bmhdHeight Raster width_ and heigth in pixels
protected int	bmhdMasking
protected int	bmhdNbPlanes Number of source bitplanes.
protected int	bmhdPageHeight Source "page" size in pixels.
protected int	bmhdPageWidth Source "page" size in pixels.
protected int	bmhdTransparentColor Transparent "color number" (sort of).
protected int	bmhdWidth Raster width_ and heigth in pixels
protected int	bmhdXAspect Pixel aspect, a ratio width : height
protected int	bmhdXPosition pixel position for this image
protected int	bmhdYAspect Pixel aspect, a ratio width : height
protected int	bmhdYPosition pixel position for this image
protected static int	BODY_ID
protected static int	CMAP_ID
protected java.awt.image.ColorModel	cmapColorModel CMAP data.
protected static int	CMP_BYTE_RUN_1 PBM BMHD chunk: compression algorithm.
protected static int	CMP_NONE PBM BMHD chunk: compression algorithm.
protected static int	CRNG_ID
protected static int	DRNG_ID
protected java.io.InputStream	inputStream Input stream to decode from.
protected java.net.URL	location URL to get the input stream from.
protected ColorCyclingMemoryImageSource	memoryImageSource BODY data
protected static int	MSK_HAS_MASK PBM BMHD chunk: masking technique.
protected static int	MSK_HAS_TRANSPARENT_COLOR PBM BMHD chunk: masking technique.
protected static int	MSK_LASSO PBM BMHD chunk: masking technique.
protected static int	MSK_NONE PBM BMHD chunk: masking technique.
protected static int	PBM_ID Chunk ID's.
protected java.util.Hashtable	properties Properties.
protected java.util.ArrayList<ColorCyclingMemoryImageSource>	sources Stores all the PBM pictures found during decoding as an instance of MemoryImageSource.

Constructor Summary

PBMDecoder(java.io.InputStream in)
Constructors

PBMDecoder(java.net.URL location)

Method Summary

protected void	decodeBMHD(IFFChunk chunk) Decodes the bitmap header (PBM BMHD).
protected void	decodeBODY(IFFChunk chunk)
protected void	decodeCMAP(IFFChunk chunk)
protected ColorCycle	decodeCRNG(IFFChunk chunk) Decodes the color range cycling (ILBM CRNG).
protected ColorCycle	decodeDRNG(IFFChunk chunk) Decodes the DPaint IV enhanced color cycle chunk (ILBM DRNG)
void	enterGroup(IFFChunk chunk)
void	leaveGroup(IFFChunk chunk)
java.util.ArrayList<ColorCyclingMemoryImageSource>	produce() Processes the input stream and creates a vector of MemoryImageSource instances.
void	registerChunks(IFFParser iff)
static int	unpackByteRun1(byte[] in, byte[] out) ByteRun1 run decoder.
void	visitChunk(IFFChunk group, IFFChunk chunk)

Methods inherited from class java.lang.Object

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

Field Detail

PBM_ID

protected static final int PBM_ID

Chunk ID's.

BMHD_ID

protected static final int BMHD_ID

CMAP_ID

protected static final int CMAP_ID

CRNG_ID

protected static final int CRNG_ID

DRNG_ID

protected static final int DRNG_ID

BODY_ID

protected static final int BODY_ID

MSK_NONE

protected static final int MSK_NONE

PBM BMHD chunk: masking technique.

See Also:

Constant Field Values

MSK_HAS_MASK

protected static final int MSK_HAS_MASK

PBM BMHD chunk: masking technique.

See Also:

Constant Field Values

MSK_HAS_TRANSPARENT_COLOR

protected static final int MSK_HAS_TRANSPARENT_COLOR

PBM BMHD chunk: masking technique.

See Also:

Constant Field Values

MSK_LASSO

protected static final int MSK_LASSO

PBM BMHD chunk: masking technique.

See Also:

Constant Field Values

CMP_NONE

protected static final int CMP_NONE

PBM BMHD chunk: compression algorithm.

See Also:

Constant Field Values

CMP_BYTE_RUN_1

protected static final int CMP_BYTE_RUN_1

PBM BMHD chunk: compression algorithm.

See Also:

Constant Field Values

inputStream

protected java.io.InputStream inputStream

Input stream to decode from.

location

protected java.net.URL location

URL to get the input stream from.

sources

protected java.util.ArrayList<ColorCyclingMemoryImageSource> sources

Stores all the PBM pictures found during decoding as an instance of MemoryImageSource.

properties

protected java.util.Hashtable properties

Properties.

bmhdWidth

protected int bmhdWidth

Raster width_ and heigth in pixels

bmhdHeight

protected int bmhdHeight

Raster width_ and heigth in pixels

bmhdXPosition

protected int bmhdXPosition

pixel position for this image

bmhdYPosition

protected int bmhdYPosition

pixel position for this image

bmhdNbPlanes

protected int bmhdNbPlanes

Number of source bitplanes.

bmhdMasking

protected int bmhdMasking

bmhdCompression

protected int bmhdCompression

bmhdTransparentColor

protected int bmhdTransparentColor

Transparent "color number" (sort of).

bmhdXAspect

protected int bmhdXAspect

Pixel aspect, a ratio width : height

bmhdYAspect

protected int bmhdYAspect

Pixel aspect, a ratio width : height

bmhdPageWidth

protected int bmhdPageWidth

Source "page" size in pixels.

bmhdPageHeight

protected int bmhdPageHeight

Source "page" size in pixels.

cmapColorModel

protected java.awt.image.ColorModel cmapColorModel

CMAP data.

memoryImageSource

protected ColorCyclingMemoryImageSource memoryImageSource

BODY data

Constructor Detail

PBMDecoder

public PBMDecoder(java.io.InputStream in)

Constructors

PBMDecoder

public PBMDecoder(java.net.URL location)

Method Detail

produce

public java.util.ArrayList<ColorCyclingMemoryImageSource> produce()
                                                           throws java.io.IOException

Processes the input stream and creates a vector of MemoryImageSource instances.

Returns:

A vector of java.awt.img.MemoryImageSource.

Throws:

java.io.IOException

registerChunks

public void registerChunks(IFFParser iff)

enterGroup

public void enterGroup(IFFChunk chunk)

Specified by:

enterGroup in interface IFFVisitor

leaveGroup

public void leaveGroup(IFFChunk chunk)

Specified by:

leaveGroup in interface IFFVisitor

visitChunk

public void visitChunk(IFFChunk group,
                       IFFChunk chunk)
                throws ParseException,
                       AbortException

Specified by:

visitChunk in interface IFFVisitor

Throws:

ParseException

AbortException

decodeBMHD

protected void decodeBMHD(IFFChunk chunk)
                   throws ParseException

Decodes the bitmap header (PBM BMHD).

 typedef UBYTE Masking; // Choice of masking technique

 #define mskNone                 0
 #define mskHasMask              1
 #define mskHasTransparentColor  2
 #define mskLasso                3

 typedef UBYTE Compression; // Choice of compression algorithm
     // applied to the rows of all source and mask planes.
     // "cmpByteRun1" is the byte run encoding. Do not compress
     // accross rows!
 #define cmpNone      0
 #define cmpByteRun1  1

 typedef struct {
   UWORD       w, h; // raster width & height in pixels
   WORD        x, y; // pixel position for this image
   UBYTE       nbPlanes; // # source bitplanes
   Masking     masking;
   Compression compression;
   UBYTE       pad1;     // unused; ignore on read, write as 0
   UWORD       transparentColor; // transparent "color number" (sort of)
   UBYTE       xAspect, yAspect; // pixel aspect, a ratio width : height
   WORD        pageWidth, pageHeight; // source "page" size in pixels
   } BitmapHeader;
 

Throws:

ParseException

decodeCMAP

protected void decodeCMAP(IFFChunk chunk)
                   throws ParseException

Throws:

ParseException

decodeCRNG

protected ColorCycle decodeCRNG(IFFChunk chunk)
                         throws ParseException

Decodes the color range cycling (ILBM CRNG).

 #define RNG_NORATE  36   // Dpaint uses this rate to mean non-active
  set {
  active = 1, reverse = 2
  } crngActive;

  // A CRange is store in a CRNG chunk.
  typedef struct {
  WORD  pad1;              // reserved for future use; store 0 here *
  WORD  rate;              // 60/sec=16384, 30/sec=8192, 1/sec=16384/60=273
  WORD set crngActive flags;     // bit0 set = active, bit 1 set = reverse
  UBYTE low; UBYTE high;         // lower and upper color registers selected
  } ilbmColorRegisterRangeChunk;
 

Throws:

ParseException

decodeDRNG

protected ColorCycle decodeDRNG(IFFChunk chunk)
                         throws ParseException

Decodes the DPaint IV enhanced color cycle chunk (ILBM DRNG)

The RNG_ACTIVE flag is set when the range is cyclable. A range should only have the RNG _ACTIVE if it:

1. contains at least one color register
2. has a defined rate
3. has more than one color and/or color register

 ILBM DRNG DPaint IV enhanced color cycle chunk
 --------------------------------------------

 set {
     RNG_ACTIVE=1,RNG_DP_RESERVED=4
 } drngFlags;

 /* True color cell * /
 typedef struct {
     UBYTE cell;
     UBYTE r;
     UBYTE g;
     UBYTE b;
 } ilbmDRNGDColor;

 /* Color register cell * /
 typedef struct {
     UBYTE cell;
     UBYTE index;
 } ilbmDRNGDIndex;

 /* DRNG chunk. * /
 typedef struct {
     UBYTE min; /* min cell value * /
     UBYTE max; /* max cell value * /
     UWORD rate; /* color cycling rate, 16384 = 60 steps/second * /
     UWORD set drngFlags flags; /* 1=RNG_ACTIVE, 4=RNG_DP_RESERVED * /
     UBYTE ntrue; /* number of DColorCell structs to follow * /
     UBYTE ntregs; /* number of DIndexCell structs to follow * /
     ilbmDRNGDColor[ntrue] trueColorCells;
     ilbmDRNGDIndex[ntregs] colorRegisterCells;
 } ilbmDRangeChunk;
 

Throws:

ParseException

decodeBODY

protected void decodeBODY(IFFChunk chunk)
                   throws ParseException

Throws:

ParseException

unpackByteRun1

public static int unpackByteRun1(byte[] in,
                                 byte[] out)
                          throws ParseException

ByteRun1 run decoder.

The run encoding scheme by byteRun1 is best described by pseudo code for the decoder Unpacker (called UnPackBits in the Macintosh toolbox.

 UnPacker:
  LOOP until produced the desired number of bytes
      Read the next source byte into n
      SELECT n FROM
          [0..127] => copy the next n+1 bytes literally
          [-1..-127] => replicate the next byte -n+1 times
          -128    => no operation
      ENDCASE;
   ENDLOOP;
 

Parameters:

in -

out -

Throws:

ParseException