us.zuercher.gpx2map.image.netpbm
Class AbstractNetpbmImage

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

All Implemented Interfaces:

Image, NetpbmImage

Direct Known Subclasses:

PamImage, PpmImage

abstract class AbstractNetpbmImage
extends Object
implements NetpbmImage

AbstractNetpbmImage Provides basic operations that apply to all Netpbm format images.

Author:

Stephan Zuercher

Field Summary

protected StringBuffer	header Exact contents of the image's header.
protected int	height Height derived from image header.
private int[][][]	imageData Cached image rasters, if any.
protected InputStream	input Image input stream.
private int	originalMaxVal Maximum pixel color value derived from image header.
protected int	width Width derived from image header.

Constructor Summary

AbstractNetpbmImage(InputStream input)
Construct a new AbstractNetpbmImage.

Method Summary

protected int	adjustToMaxVal255(int value) Utility method to convert a given Netpbm value to a maxval of 255.
void	close() Closes the image file.
String	getHeader() Returns an exact copy of the image file's header.
int	getHeight() Returns the image's height.
int	getMaxVal() Returns the image's maximum pixel color value.
protected int	getOriginalBytesPerPixelPerColor() Returns the number of bytes per pixel per color: 1 or 2.
int[][][]	getRaster() Implements Image.getRaster() by repeatedly calling Image.getNextRasterLine().
int	getWidth() Returns the image's width.
(package private) abstract void	readHeader() Reads the Netpbm image's header information and populates the fields of this class.
protected String	readWord(boolean skipPostFieldWS) Reads a "word" from the Netpbm image header.
protected void	setOriginalMaxVal(int originalMaxVal)
protected void	skipWS(boolean crLfOnly) Skips whitespace on the input stream.

Methods inherited from class java.lang.Object

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

Methods inherited from interface us.zuercher.gpx2map.image.Image

getDepth, getNextRasterLine, hasAlphaChannel

Field Detail

header

protected StringBuffer header

Exact contents of the image's header.

input

protected final InputStream input

Image input stream.

width

protected int width

Width derived from image header.

height

protected int height

Height derived from image header.

originalMaxVal

private int originalMaxVal

Maximum pixel color value derived from image header. 1-65535.

imageData

private int[][][] imageData

Cached image rasters, if any.

Constructor Detail

AbstractNetpbmImage

AbstractNetpbmImage(InputStream input)

Construct a new AbstractNetpbmImage.

Parameters:

input - image input stream

Method Detail

readHeader

abstract void readHeader()
                  throws IOException

Reads the Netpbm image's header information and populates the fields of this class.

Throws:

IOException - if there's an error reading the image stream or if the stream does not conform to the Netpbm format.

getHeader

public String getHeader()
                 throws IOException

Returns an exact copy of the image file's header. This is useful for writing a new copy of the image with header comments unchanged.

Returns:

the image header

Throws:

IOException - if the image header cannot be read or is otherwise invalid

getWidth

public int getWidth()

Returns the image's width.

Specified by:

getWidth in interface Image

Returns:

the image's width.

getHeight

public int getHeight()

Returns the image's height.

Specified by:

getHeight in interface Image

Returns:

the image's height.

getMaxVal

public int getMaxVal()

Returns the image's maximum pixel color value. Always 255.

Specified by:

getMaxVal in interface NetpbmImage

Returns:

the image's maximum pixel color value, 255.

getOriginalBytesPerPixelPerColor

protected int getOriginalBytesPerPixelPerColor()

Returns the number of bytes per pixel per color: 1 or 2.

Returns:

the number of bytes per pixel per color: 1 or 2.

close

public void close()
           throws IOException

Closes the image file.

Specified by:

close in interface Image

Throws:

IOException - if there's an error closing the file

getRaster

public int[][][] getRaster()
                    throws IOException

Implements Image.getRaster() by repeatedly calling Image.getNextRasterLine().

Specified by:

getRaster in interface Image

Returns:

an array of image rasters for this image, as specified by Image.getRaster().

Throws:

IOException - if there's an error reading or closing the image.

readWord

protected String readWord(boolean skipPostFieldWS)
                   throws IOException

Reads a "word" from the Netpbm image header. Assumes that the first character read from the input stream is the first character of the word or of a header comment. If asked, skips whitespace following the word to prepare for the next call to this method.

Parameters:

skipPostFieldWS - skip whitespace after the word is read

Returns:

the word read

Throws:

IOException - if there's an error reading the file

skipWS

protected void skipWS(boolean crLfOnly)
               throws IOException

Skips whitespace on the input stream.

Parameters:

crLfOnly - if true, only skips carriage return or linefeed characters.

Throws:

IOException - if there's an error reading the file

setOriginalMaxVal

protected void setOriginalMaxVal(int originalMaxVal)

adjustToMaxVal255

protected int adjustToMaxVal255(int value)

Utility method to convert a given Netpbm value to a maxval of 255. Uses originalMaxVal as the basis for conversion.

Parameters:

value - value to convert

Returns:

value scaled to max val 255