Class PBMDecoder

java.lang.Object
org.monte.media.pbm.PBMDecoder
All Implemented Interfaces:
IFFVisitor
public class PBMDecoder extends 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]".
Author:
Werner Randelshofer, Hausmatt 10, CH-6405 Goldau, Switzerland

  • Field Details

    • 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:

    • MSK_HAS_MASK

      protected static final int MSK_HAS_MASK
      PBM BMHD chunk: masking technique.
      See Also:

    • MSK_HAS_TRANSPARENT_COLOR

      protected static final int MSK_HAS_TRANSPARENT_COLOR
      PBM BMHD chunk: masking technique.
      See Also:

    • MSK_LASSO

      protected static final int MSK_LASSO
      PBM BMHD chunk: masking technique.
      See Also:

    • CMP_NONE

      protected static final int CMP_NONE
      PBM BMHD chunk: compression algorithm.
      See Also:

    • CMP_BYTE_RUN_1

      protected static final int CMP_BYTE_RUN_1
      PBM BMHD chunk: compression algorithm.
      See Also:

    • inputStream

      protected InputStream inputStream
      Input stream to decode from.

    • location

      protected URL location
      URL to get the input stream from.

    • sources

      protected ArrayList<ColorCyclingMemoryImageSource> sources
      Stores all the PBM pictures found during decoding as an instance of MemoryImageSource.

    • 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 ColorModel cmapColorModel
      CMAP data.

    • memoryImageSource

      protected ColorCyclingMemoryImageSource memoryImageSource
      BODY data

  • Constructor Details

    • PBMDecoder

      public PBMDecoder(InputStream in)
      Constructors

    • PBMDecoder

      public PBMDecoder(URL location)

  • Method Details

    • produce

      public ArrayList<ColorCyclingMemoryImageSource> produce() throws IOException
      Processes the input stream and creates a vector of MemoryImageSource instances.
      Returns:
      A vector of java.awt.img.MemoryImageSource.
      Throws:
      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 and 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