PngHelperInternal (PNGJ 2.0.1 API)

java.lang.Object
- ar.com.hjg.pngj.PngHelperInternal

```
public final class PngHelperInternal
extends Object
```
Some utility static methods for internal use.
Client code should not normally use this class

Field Summary

Fields
Modifier and Type	Field and Description
`static Charset`	`charsetLatin1`
`static String`	`charsetLatin1name` Default charset, used internally by PNG for several things
`static Charset`	`charsetUTF8`
`static String`	`charsetUTF8name` UTF-8 is only used for some chunks
`static String`	`KEY_LOGGER`
`static Logger`	`LOGGER`

Constructor Summary

Constructors
Constructor and Description

PngHelperInternal()

Constructors
Constructor and Description
`PngHelperInternal()`

Method Summary

Methods
Modifier and Type	Method and Description
`static int`	`doubleToInt100000(double d)`
`static int`	`filterRowAverage(int r, int left, int up)`
`static int`	`filterRowNone(int r)`
`static int`	`filterRowPaeth(int r, int left, int up, int upleft)`
`static int`	`filterRowSub(int r, int left)`
`static int`	`filterRowUp(int r, int up)`
`static long`	`getCrctestVal(PngReader pngr)`
`static byte[]`	`getPngIdSignature()` PNG magic bytes
`static void`	`initCrcForTests(PngReader pngr)`
`static double`	`intToDouble100000(int i)`
`static void`	`logdebug(String msg)`
`static int`	`readByte(InputStream is)`
`static void`	`readBytes(InputStream is, byte[] b, int offset, int len)` guaranteed to read exactly len bytes.
`static int`	`readInt1fromByte(byte[] b, int offset)`
`static int`	`readInt2(InputStream is)` -1 if eof PNG uses "network byte order"
`static int`	`readInt2fromBytes(byte[] b, int offset)`
`static int`	`readInt4(InputStream is)` -1 if eof
`static int`	`readInt4fromBytes(byte[] b, int offset)`
`static void`	`skipBytes(InputStream is, long len)`
`static void`	`writeByte(OutputStream os, byte b)`
`static void`	`writeByte(OutputStream os, byte[] bs)`
`static void`	`writeBytes(OutputStream os, byte[] b)`
`static void`	`writeBytes(OutputStream os, byte[] b, int offset, int n)`
`static void`	`writeInt2(OutputStream os, int n)`
`static void`	`writeInt2tobytes(int n, byte[] b, int offset)`
`static void`	`writeInt4(OutputStream os, int n)`
`static void`	`writeInt4tobytes(int n, byte[] b, int offset)`

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

Field Detail

KEY_LOGGER
```
public static final String KEY_LOGGER
```
See Also:
Constant Field Values

LOGGER
```
public static final Logger LOGGER
```

charsetLatin1name
```
public static String charsetLatin1name
```
Default charset, used internally by PNG for several things

charsetLatin1
```
public static Charset charsetLatin1
```

charsetUTF8name
```
public static String charsetUTF8name
```
UTF-8 is only used for some chunks

charsetUTF8
```
public static Charset charsetUTF8
```

Constructor Detail
- PngHelperInternal
```
public PngHelperInternal()
```

Method Detail

getPngIdSignature

public static byte[] getPngIdSignature()

PNG magic bytes

doubleToInt100000

public static int doubleToInt100000(double d)

intToDouble100000

public static double intToDouble100000(int i)

readByte

public static int readByte(InputStream is)

readInt2
```
public static int readInt2(InputStream is)
```
-1 if eof PNG uses "network byte order"

readInt4

public static int readInt4(InputStream is)

-1 if eof

readInt1fromByte

public static int readInt1fromByte(byte[] b,
                   int offset)

readInt2fromBytes

public static int readInt2fromBytes(byte[] b,
                    int offset)

readInt4fromBytes

public static final int readInt4fromBytes(byte[] b,
                    int offset)

writeByte

public static void writeByte(OutputStream os,
             byte b)

writeByte

public static void writeByte(OutputStream os,
             byte[] bs)

writeInt2

public static void writeInt2(OutputStream os,
             int n)

writeInt4

public static void writeInt4(OutputStream os,
             int n)

writeInt2tobytes

public static void writeInt2tobytes(int n,
                    byte[] b,
                    int offset)

writeInt4tobytes

public static void writeInt4tobytes(int n,
                    byte[] b,
                    int offset)

readBytes

public static void readBytes(InputStream is,
             byte[] b,
             int offset,
             int len)

guaranteed to read exactly len bytes. throws error if it can't

skipBytes

public static void skipBytes(InputStream is,
             long len)

writeBytes

public static void writeBytes(OutputStream os,
              byte[] b)

writeBytes

public static void writeBytes(OutputStream os,
              byte[] b,
              int offset,
              int n)

logdebug

public static void logdebug(String msg)

filterRowNone

public static int filterRowNone(int r)

filterRowSub

public static int filterRowSub(int r,
               int left)

filterRowUp

public static int filterRowUp(int r,
              int up)

filterRowAverage

public static int filterRowAverage(int r,
                   int left,
                   int up)

filterRowPaeth

public static int filterRowPaeth(int r,
                 int left,
                 int up,
                 int upleft)

initCrcForTests

public static final void initCrcForTests(PngReader pngr)

getCrctestVal

public static final long getCrctestVal(PngReader pngr)

Class PngHelperInternal

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

KEY_LOGGER

LOGGER

charsetLatin1name

charsetLatin1

charsetUTF8name

charsetUTF8

Constructor Detail

PngHelperInternal

Method Detail

getPngIdSignature

doubleToInt100000

intToDouble100000

readByte

readInt2

readInt4

readInt1fromByte

readInt2fromBytes

readInt4fromBytes

writeByte

writeByte

writeInt2

writeInt4

writeInt2tobytes

writeInt4tobytes

readBytes

skipBytes

writeBytes

writeBytes

logdebug

filterRowNone

filterRowSub

filterRowUp

filterRowAverage

filterRowPaeth

initCrcForTests

getCrctestVal