PNGEncoder (FreeHEP Vector Graphics 2.2.2-SNAPSHOT API)

java.lang.Object
- org.freehep.graphicsio.png.PNGEncoder

All Implemented Interfaces:: ImageObserver

public class PNGEncoder
extends Object
implements ImageObserver

Field Summary

Fields
Modifier and Type	Field and Description
`protected int`	`bytePos`
`protected int`	`bytesPerPixel`
`protected int`	`compressionLevel`
`protected CRC32`	`crc`
`protected long`	`crcValue`
`protected int`	`dataPos`
`static boolean`	`ENCODE_ALPHA` Constant specifying that alpha channel should be encoded.
`protected boolean`	`encodeAlpha`
`protected int`	`endPos`
`protected int`	`filter`
`static int`	`FILTER_LAST`
`static int`	`FILTER_NONE` Constants for filters
`static int`	`FILTER_SUB`
`static int`	`FILTER_UP`
`protected int`	`hdrPos`
`protected int`	`height`
`protected Image`	`image`
`protected List<String>`	`keys`
`protected byte[]`	`leftBytes`
`protected int`	`maxPos`
`static boolean`	`NO_ALPHA` Constant specifying that alpha channel should not be encoded.
`protected byte[]`	`pngBytes`
`protected byte[]`	`priorRow`
`protected List<String>`	`text`
`protected int`	`width`

Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

Constructors
Constructor and Description
`PNGEncoder()`
`PNGEncoder(Image image)` Class constructor specifying Image to encode, with no alpha channel encoding.
`PNGEncoder(Image image, boolean encodeAlpha)` Class constructor specifying Image to encode, and whether to encode alpha.
`PNGEncoder(Image image, boolean encodeAlpha, int whichFilter)` Class constructor specifying Image to encode, whether to encode alpha, and filter to use.
`PNGEncoder(Image image, boolean encodeAlpha, int whichFilter, int compLevel)` Class constructor specifying Image source to encode, whether to encode alpha, filter to use, and compression level.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addText(String key, String value)`
`protected void`	`filterSub(byte[] pixels, int startPos, int width)` Perform "sub" filtering on the given row.
`protected void`	`filterUp(byte[] pixels, int startPos, int width)` Perform "up" filtering on the given row.
`int`	`getCompressionLevel()` Retrieve compression level
`boolean`	`getEncodeAlpha()` Retrieve alpha encoding status.
`int`	`getFilter()` Retrieve filtering scheme
`boolean`	`imageUpdate(Image image, int flags, int x, int y, int width, int height)`
`byte[]`	`pngEncode()` Creates an array of bytes that is the PNG equivalent of the current image.
`byte[]`	`pngEncode(boolean encodeAlpha)` Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.
`protected byte[]`	`resizeByteArray(byte[] array, int newLength)` Increase or decrease the length of a byte array.
`void`	`setCompressionLevel(int level)` Set the compression level to use
`void`	`setEncodeAlpha(boolean encodeAlpha)` Set the alpha encoding on or off.
`void`	`setFilter(int whichFilter)` Set the filter to use
`void`	`setImage(Image image)` Set the image to be encoded
`protected int`	`writeByte(int b, int offset)` Write a single byte into the pngBytes array at a given position.
`protected int`	`writeBytes(byte[] data, int offset)` Write an array of bytes into the pngBytes array.
`protected int`	`writeBytes(byte[] data, int nBytes, int offset)` Write an array of bytes into the pngBytes array, specifying number of bytes to write.
`protected void`	`writeEnd()` Write a PNG "IEND" chunk into the pngBytes array.
`protected void`	`writeHeader()` Write a PNG "IHDR" chunk into the pngBytes array.
`protected boolean`	`writeImageData()` Write the image data into the pngBytes array.
`protected int`	`writeInt2(int n, int offset)` Write a two-byte integer into the pngBytes array at a given position.
`protected int`	`writeInt4(int n, int offset)` Write a four-byte integer into the pngBytes array at a given position.
`protected int`	`writeString(String s, int offset)` Write a string into the pngBytes array at a given position.
`protected void`	`writeText(String key, String value)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ENCODE_ALPHA
```
public static final boolean ENCODE_ALPHA
```
    Constant specifying that alpha channel should be encoded.
    
    See Also:
    Constant Field Values
  - NO_ALPHA
```
public static final boolean NO_ALPHA
```
    Constant specifying that alpha channel should not be encoded.
    
    See Also:
    Constant Field Values
  - FILTER_NONE
```
public static final int FILTER_NONE
```
    Constants for filters
    
    See Also:
    Constant Field Values
  - FILTER_SUB
```
public static final int FILTER_SUB
```
    See Also:
    Constant Field Values
  - FILTER_UP
```
public static final int FILTER_UP
```
    See Also:
    Constant Field Values
  - FILTER_LAST
```
public static final int FILTER_LAST
```
    See Also:
    Constant Field Values
  - pngBytes
```
protected byte[] pngBytes
```
  - priorRow
```
protected byte[] priorRow
```
  - leftBytes
```
protected byte[] leftBytes
```
  - image
```
protected Image image
```
  - width
```
protected int width
```
  - height
```
protected int height
```
  - bytePos
```
protected int bytePos
```
  - maxPos
```
protected int maxPos
```
  - hdrPos
```
protected int hdrPos
```
  - dataPos
```
protected int dataPos
```
  - endPos
```
protected int endPos
```
  - crc
```
protected CRC32 crc
```
  - crcValue
```
protected long crcValue
```
  - encodeAlpha
```
protected boolean encodeAlpha
```
  - filter
```
protected int filter
```
  - bytesPerPixel
```
protected int bytesPerPixel
```
  - compressionLevel
```
protected int compressionLevel
```
  - keys
```
protected List<String> keys
```
  - text
```
protected List<String> text
```
- Constructor Detail
  - PNGEncoder
```
public PNGEncoder()
```
  - PNGEncoder
```
public PNGEncoder(Image image)
```
    Class constructor specifying Image to encode, with no alpha channel encoding.
    
    Parameters:
    image - A Java Image object which uses the DirectColorModel
    See Also:
    Image
  - PNGEncoder
```
public PNGEncoder(Image image,
          boolean encodeAlpha)
```
    Class constructor specifying Image to encode, and whether to encode alpha.
    
    Parameters:
    image - A Java Image object which uses the DirectColorModel
    encodeAlpha - Encode the alpha channel? false=no; true=yes
    See Also:
    Image
  - PNGEncoder
```
public PNGEncoder(Image image,
          boolean encodeAlpha,
          int whichFilter)
```
    Class constructor specifying Image to encode, whether to encode alpha, and filter to use.
    
    Parameters:
    image - A Java Image object which uses the DirectColorModel
    encodeAlpha - Encode the alpha channel? false=no; true=yes
    whichFilter - 0=none, 1=sub, 2=up
    See Also:
    Image
  - PNGEncoder
```
public PNGEncoder(Image image,
          boolean encodeAlpha,
          int whichFilter,
          int compLevel)
```
    Class constructor specifying Image source to encode, whether to encode alpha, filter to use, and compression level.
    
    Parameters:
    image - A Java Image object
    encodeAlpha - Encode the alpha channel? false=no; true=yes
    whichFilter - 0=none, 1=sub, 2=up
    compLevel - 0..9
    See Also:
    Image
- Method Detail
  - addText
```
public void addText(String key,
           String value)
```
  - setImage
```
public void setImage(Image image)
```
    Set the image to be encoded
    
    Parameters:
    image - A Java Image object which uses the DirectColorModel
    See Also:
    Image
  - imageUpdate
```
public boolean imageUpdate(Image image,
                  int flags,
                  int x,
                  int y,
                  int width,
                  int height)
```
    Specified by:
    
    imageUpdate in interface ImageObserver
  - pngEncode
```
public byte[] pngEncode(boolean encodeAlpha)
```
    Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.
    
    Parameters:
    encodeAlpha - boolean false=no alpha, true=encode alpha
    
    Returns:
    an array of bytes, or null if there was a problem
  - pngEncode
```
public byte[] pngEncode()
```
    Creates an array of bytes that is the PNG equivalent of the current image. Alpha encoding is determined by its setting in the constructor.
    
    Returns:
    an array of bytes, or null if there was a problem
  - setEncodeAlpha
```
public void setEncodeAlpha(boolean encodeAlpha)
```
    Set the alpha encoding on or off.
    
    Parameters:
    encodeAlpha - false=no, true=yes
  - getEncodeAlpha
```
public boolean getEncodeAlpha()
```
    Retrieve alpha encoding status.
    
    Returns:
    boolean false=no, true=yes
  - setFilter
```
public void setFilter(int whichFilter)
```
    Set the filter to use
    
    Parameters:
    whichFilter - from constant list
  - getFilter
```
public int getFilter()
```
    Retrieve filtering scheme
    
    Returns:
    int (see constant list)
  - setCompressionLevel
```
public void setCompressionLevel(int level)
```
    Set the compression level to use
    
    Parameters:
    level - 0 through 9
  - getCompressionLevel
```
public int getCompressionLevel()
```
    Retrieve compression level
    
    Returns:
    int in range 0-9
  - resizeByteArray
```
protected byte[] resizeByteArray(byte[] array,
                     int newLength)
```
    Increase or decrease the length of a byte array.
    
    Parameters:
    array - The original array.
    newLength - The length you wish the new array to have.
    
    Returns:
    Array of newly desired length. If shorter than the original, the trailing elements are truncated.
  - writeBytes
```
protected int writeBytes(byte[] data,
             int offset)
```
    Write an array of bytes into the pngBytes array. Note: This routine has the side effect of updating maxPos, the largest element written in the array. The array is resized by 1000 bytes or the length of the data to be written, whichever is larger.
    
    Parameters:
    data - The data to be written into pngBytes.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
  - writeBytes
```
protected int writeBytes(byte[] data,
             int nBytes,
             int offset)
```
    Write an array of bytes into the pngBytes array, specifying number of bytes to write. Note: This routine has the side effect of updating maxPos, the largest element written in the array. The array is resized by 1000 bytes or the length of the data to be written, whichever is larger.
    
    Parameters:
    data - The data to be written into pngBytes.
    nBytes - The number of bytes to be written.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
  - writeInt2
```
protected int writeInt2(int n,
            int offset)
```
    Write a two-byte integer into the pngBytes array at a given position.
    
    Parameters:
    n - The integer to be written into pngBytes.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
  - writeInt4
```
protected int writeInt4(int n,
            int offset)
```
    Write a four-byte integer into the pngBytes array at a given position.
    
    Parameters:
    n - The integer to be written into pngBytes.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
  - writeByte
```
protected int writeByte(int b,
            int offset)
```
    Write a single byte into the pngBytes array at a given position.
    
    Parameters:
    b - The integer to be written into pngBytes.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
  - writeString
```
protected int writeString(String s,
              int offset)
```
    Write a string into the pngBytes array at a given position. This uses the getBytes method, so the encoding used will be its default.
    
    Parameters:
    s - The String to be written into pngBytes.
    offset - The starting point to write to.
    
    Returns:
    The next place to be written to in the pngBytes array.
    See Also:
    String.getBytes()
  - writeHeader
```
protected void writeHeader()
```
    Write a PNG "IHDR" chunk into the pngBytes array.
  - writeText
```
protected void writeText(String key,
             String value)
```
  - filterSub
```
protected void filterSub(byte[] pixels,
             int startPos,
             int width)
```
    Perform "sub" filtering on the given row. Uses temporary array leftBytes to store the original values of the previous pixels. The array is 16 bytes long, which will easily hold two-byte samples plus two-byte alpha.
    
    Parameters:
    pixels - The array holding the scan lines being built
    startPos - Starting position within pixels of bytes to be filtered.
    width - Width of a scanline in pixels.
  - filterUp
```
protected void filterUp(byte[] pixels,
            int startPos,
            int width)
```
    Perform "up" filtering on the given row. Side effect: refills the prior row with current row
    
    Parameters:
    pixels - The array holding the scan lines being built
    startPos - Starting position within pixels of bytes to be filtered.
    width - Width of a scanline in pixels.
  - writeImageData
```
protected boolean writeImageData()
```
    Write the image data into the pngBytes array. This will write one or more PNG "IDAT" chunks. In order to conserve memory, this method grabs as many rows as will fit into 32K bytes, or the whole image; whichever is less.
    
    Returns:
    true if no errors; false if error grabbing pixels
  - writeEnd
```
protected void writeEnd()
```
    Write a PNG "IEND" chunk into the pngBytes array.

Class PNGEncoder

Field Summary

Fields inherited from interface java.awt.image.ImageObserver

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ENCODE_ALPHA

NO_ALPHA

FILTER_NONE

FILTER_SUB

FILTER_UP

FILTER_LAST

pngBytes

priorRow

leftBytes

image

width

height

bytePos

maxPos

hdrPos

dataPos

endPos

crc

crcValue

encodeAlpha

filter

bytesPerPixel

compressionLevel

keys

text

Constructor Detail

PNGEncoder

PNGEncoder

PNGEncoder

PNGEncoder

PNGEncoder

Method Detail

addText

setImage

imageUpdate

pngEncode

pngEncode

setEncodeAlpha

getEncodeAlpha

setFilter

getFilter

setCompressionLevel

getCompressionLevel

resizeByteArray

writeBytes

writeBytes

writeInt2

writeInt4

writeByte

writeString

writeHeader

writeText

filterSub

filterUp

writeImageData

writeEnd