us.zuercher.gpx2map.image.netpbm
Class WritablePpmImage

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

public class WritablePpmImage
extends Object

WritablePpmImage is a write-only representation of a PPM image. It writes only the binary version of the PPM format, with optional gzip compression.

Author:

Stephan Zuercher

Field Summary

private int	bytesPerPixelPerColor Image bytes per pixel color.
private boolean	gzip Compression flag.
private StringBuffer	header Header buffer typically copied from another image.
private int	height Image height.
private static String	MAGIC PPM magic token.
private int	maxVal Image maximum pixel color value.
private static String	NL PPM header line separator.
private OutputStream	output Output stream.
private File	ppmImageFile PPM file location.
private int	rastersWritten Count of rastersWritten (compared to height).
private int	width Image width.

Constructor Summary

WritablePpmImage(File ppmImageFile, int width, int height, int maxVal, boolean gzip)
Constructs a new WritablePpmImage with the given header information.

WritablePpmImage(File ppmImageFile, PpmImage headerSource, boolean gzip)
Constructs a new WritablePpmImage, copying the image header from a PpmImage.

Method Summary

void	close() Closes the image file.
private void	writeHeader() Writes the PPM header.
void	writeRaster(int[][] raster) Write a raster line to the image file.
void	writeRaster(int[][] raster, int offset) Write a raster line to the image file.

Methods inherited from class java.lang.Object

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

Field Detail

MAGIC

private static final String MAGIC

PPM magic token.

See Also:

Constant Field Values

NL

private static final String NL

PPM header line separator.

See Also:

Constant Field Values

ppmImageFile

private final File ppmImageFile

PPM file location.

header

private final StringBuffer header

Header buffer typically copied from another image.

gzip

private final boolean gzip

Compression flag.

width

private final int width

Image width.

height

private final int height

Image height.

maxVal

private final int maxVal

Image maximum pixel color value. 1-65535.

bytesPerPixelPerColor

private final int bytesPerPixelPerColor

Image bytes per pixel color. 1 or 2.

output

private OutputStream output

Output stream.

rastersWritten

private int rastersWritten

Count of rastersWritten (compared to height).

Constructor Detail

WritablePpmImage

public WritablePpmImage(File ppmImageFile,
                        PpmImage headerSource,
                        boolean gzip)
                 throws IOException

Constructs a new WritablePpmImage, copying the image header from a PpmImage.

Parameters:

ppmImageFile - output file location

headerSource - source of header information

gzip - compression flag

Throws:

IOException - if the header source's header data cannot be read

WritablePpmImage

public WritablePpmImage(File ppmImageFile,
                        int width,
                        int height,
                        int maxVal,
                        boolean gzip)

Constructs a new WritablePpmImage with the given header information.

Parameters:

ppmImageFile - output file location

width - image width in pixels

height - image height in pixels

maxVal - maximum pixel color value (255 or 65535)

gzip - compression flag

Method Detail

writeRaster

public void writeRaster(int[][] raster)
                 throws IOException

Write a raster line to the image file. Each pixel is comprised of 3 integers: red, green, blue. Extra integers (e.g. alpha channels from a PAM image) are silently ignored. If the raster is wider than necessary, extra data is ignored.

Parameters:

raster - an array of pixel data of size int[width][3].

Throws:

IOException - if there's an error writing to the file

IllegalArgumentException - if more than height raster are written, or if the given raster line has the wrong width

writeRaster

public void writeRaster(int[][] raster,
                        int offset)
                 throws IOException

Write a raster line to the image file. Each pixel is comprised of 3 integers: red, green, blue. Extra integers (e.g. alpha channels from a PAM image) are silently ignored.

Parameters:

raster - an array of pixel data of size int[][3].

offset - offset into raster array

Throws:

IOException - if there's an error writing to the file

IllegalArgumentException - if more than height raster are written, or if the raster does not contain enough data to write a full width raster line (e.g. raster.length - offset < width)

close

public void close()
           throws IOException

Closes the image file.

Throws:

IOException - if there's an error flushing or closing the file

IllegalStateException - if height rasters have not been written

writeHeader

private void writeHeader()
                  throws IOException

Writes the PPM header.

Throws:

IOException - if there's an error writing to the file.