us.zuercher.gpx2map.image.netpbm
Class PamImage

java.lang.Object
  us.zuercher.gpx2map.image.netpbm.AbstractNetpbmImage
      us.zuercher.gpx2map.image.netpbm.PamImage

All Implemented Interfaces:

Image, NetpbmImage

public class PamImage
extends AbstractNetpbmImage

PamImage is a read-only representation of a PAM image. It supports both reading 1- and 2-byte pixel color values. Images are converted to "maxval 255" as part of loading.

Author:

Stephan Zuercher

Field Summary

private boolean	blackWhite Flag indicating that the tuple type is TUPLTYPE_BLACKANDWHITE.
private int	depth File depth.
private static String	DEPTH_HEADER Depth header keyord.
private boolean	grayscale Flag indicating that the tuple type is TUPLTYPE_GRAYSCALE.
private boolean	hasAlphaChannel Flag indicating whether the tuple type included the TUPLTYPE_ALPHA_SUFFIX suffix.
private static String	HEIGHT_HEADER Height header keyord.
private static String	MAXVAL_HEADER Maxval header keyord.
static String	NETPBM_PAM_MAGIC_NUMBER Netpbm PAM image file magic number.
private int[][]	rasterLine Pixelized raster line.
private byte[]	rasterLineData Buffer space for a single raster-line of the image.
private static String	TUPLTYPE_ALPHA_SUFFIX Tuple type suffix that indicates an alpha channel is present.
private static String	TUPLTYPE_BLACKANDWHITE Black and white tuple type.
private static String	TUPLTYPE_GRAYSCALE Grayscale tuple type.
private static String	TUPLTYPE_HEADER Tuple type header keyword.
private static String	TUPLTYPE_RGB RGB tuple type.
private static String	WIDTH_HEADER Width header keyord.

Fields inherited from class us.zuercher.gpx2map.image.netpbm.AbstractNetpbmImage

header, height, input, width

Constructor Summary

PamImage(InputStream pamInputStream)
Constructs a new PamImage from an InputStream.

Method Summary

int	getDepth() Returns this PAM image's depth.
int[][]	getNextRasterLine() Reads the next raster from the PAM file.
boolean	hasAlphaChannel() PAM images may not contain alpha-channel information.
protected void	readHeader() Reads the image's header block.

Methods inherited from class us.zuercher.gpx2map.image.netpbm.AbstractNetpbmImage

adjustToMaxVal255, close, getHeader, getHeight, getMaxVal, getOriginalBytesPerPixelPerColor, getRaster, getWidth, readWord, setOriginalMaxVal, skipWS

Methods inherited from class java.lang.Object

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

Field Detail

NETPBM_PAM_MAGIC_NUMBER

public static final String NETPBM_PAM_MAGIC_NUMBER

Netpbm PAM image file magic number.

See Also:

Constant Field Values

WIDTH_HEADER

private static final String WIDTH_HEADER

Width header keyord.

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Constant Field Values

HEIGHT_HEADER

private static final String HEIGHT_HEADER

Height header keyord.

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Constant Field Values

DEPTH_HEADER

private static final String DEPTH_HEADER

Depth header keyord.

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Constant Field Values

MAXVAL_HEADER

private static final String MAXVAL_HEADER

Maxval header keyord.

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Constant Field Values

TUPLTYPE_HEADER

private static final String TUPLTYPE_HEADER

Tuple type header keyword.

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Constant Field Values

TUPLTYPE_RGB

private static final String TUPLTYPE_RGB

RGB tuple type.

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Constant Field Values

TUPLTYPE_GRAYSCALE

private static final String TUPLTYPE_GRAYSCALE

Grayscale tuple type.

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Constant Field Values

TUPLTYPE_BLACKANDWHITE

private static final String TUPLTYPE_BLACKANDWHITE

Black and white tuple type.

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Constant Field Values

TUPLTYPE_ALPHA_SUFFIX

private static final String TUPLTYPE_ALPHA_SUFFIX

Tuple type suffix that indicates an alpha channel is present.

See Also:

Constant Field Values

blackWhite

private boolean blackWhite

Flag indicating that the tuple type is TUPLTYPE_BLACKANDWHITE.

grayscale

private boolean grayscale

Flag indicating that the tuple type is TUPLTYPE_GRAYSCALE.

depth

private int depth

File depth. Indicates the number of channels in the file. Only depths 1 and 3 are supported without an alpha channel. With an alpha channel, only depths 2 and 4 are supported.

hasAlphaChannel

private boolean hasAlphaChannel

Flag indicating whether the tuple type included the TUPLTYPE_ALPHA_SUFFIX suffix.

rasterLineData

private byte[] rasterLineData

Buffer space for a single raster-line of the image. This is the image AbstractNetpbmImage.getWidth() multiplied by depth, multiplied by the number of bytes per pixel color (AbstractNetpbmImage.getOriginalBytesPerPixelPerColor(), 1 or 2).

rasterLine

private int[][] rasterLine

Pixelized raster line. Size is int[width][depth].

Constructor Detail

PamImage

PamImage(InputStream pamInputStream)

Constructs a new PamImage from an InputStream.

Parameters:

pamInputStream - PAM image input stream

Method Detail

hasAlphaChannel

public boolean hasAlphaChannel()

PAM images may not contain alpha-channel information.

Returns:

true if ths image supports alpha-channel, false otherwise

getDepth

public int getDepth()

Returns this PAM image's depth.

Returns:

the depth of this PAM image.

getNextRasterLine

public int[][] getNextRasterLine()
                          throws IOException

Reads the next raster from the PAM file. Note that the array returned by this method is re-used for each subsequent call to this method. If you need to keep a copy of the raster beyond the next call to this method, make a copy of it.

The dimension of the second rank of the array is always 3 or 4. If hasAlphaChannel() returns true, it will be 4. It is 3 otherwise. The first three indices are always the red, green and blue color values, respectively. This is true even if the underlying image format is grayscale or black and white. The PBM or PGM implementations are expected to expand their data to conform to this rule. Also, PBM images should invert the sense of their data such correct RGB values for black and white are returned.

Returns:

next raster or null if EOF

Throws:

IOException - on file error

readHeader

protected void readHeader()
                   throws IOException

Reads the image's header block.

Specified by:

readHeader in class AbstractNetpbmImage

Throws:

IOException - if the image head cannot be read or is invalid