Shape Arabic text on a character basis.
ArabicShaping performs basic operations for "shaping" Arabic text. It is most
useful for use with legacy data formats and legacy display technology
(simple terminals). All operations are performed on Unicode characters.
Text-based shaping means that some character code points in the text are
replaced by others depending on the context. It transforms one kind of text
into another. In comparison, modern displays for Arabic text select
appropriate, context-dependent font glyphs for each text element, which means
that they transform text into a glyph vector.
Text transformations are necessary when modern display technology is not
available or when text needs to be transformed to or from legacy formats that
use "shaped" characters. Since the Arabic script is cursive, connecting
adjacent letters to each other, computers select images for each letter based
on the surrounding letters. This usually results in four images per Arabic
letter: initial, middle, final, and isolated forms. In Unicode, on the other
hand, letters are normally stored abstract, and a display system is expected
to select the necessary glyphs. (This makes searching and other text
processing easier because the same letter has only one code.) It is possible
to mimic this with text transformations because there are characters in
Unicode that are rendered as letters with a specific shape
(or cursive connectivity). They were included for interoperability with
legacy systems and codepages, and for unsophisticated display systems.
A second kind of text transformations is supported for Arabic digits:
For compatibility with legacy codepages that only include European digits,
it is possible to replace one set of digits by another, changing the
character code points. These operations can be performed for either
Arabic-Indic Digits (U+0660...U+0669) or Eastern (Extended) Arabic-Indic
digits (U+06f0...U+06f9).
Some replacements may result in more or fewer characters (code points).
By default, this means that the destination buffer may receive text with a
length different from the source length. Some legacy systems rely on the
length of the text to be constant. They expect extra spaces to be added
or consumed either next to the affected character or at the end of the
text.
DIGITS_AN2EN
public static final int DIGITS_AN2EN
Digit shaping option: Replace Arabic-Indic digits by European digits (U+0030...U+0039).
DIGITS_EN2AN
public static final int DIGITS_EN2AN
Digit shaping option: Replace European digits (U+0030...U+0039) by Arabic-Indic digits.
DIGITS_EN2AN_INIT_AL
public static final int DIGITS_EN2AN_INIT_AL
Digit shaping option:
Replace European digits (U+0030...U+0039) by Arabic-Indic digits
if the most recent strongly directional character
is an Arabic letter (its Bidi direction value is RIGHT_TO_LEFT_ARABIC).
The initial state at the start of the text is assumed to be an Arabic,
letter, so European digits at the start of the text will change.
Compare to DIGITS_ALEN2AN_INT_LR.
DIGITS_EN2AN_INIT_LR
public static final int DIGITS_EN2AN_INIT_LR
Digit shaping option:
Replace European digits (U+0030...U+0039) by Arabic-Indic digits
if the most recent strongly directional character
is an Arabic letter (its Bidi direction value is RIGHT_TO_LEFT_ARABIC).
The initial state at the start of the text is assumed to be not an Arabic,
letter, so European digits at the start of the text will not change.
Compare to DIGITS_ALEN2AN_INIT_AL.
DIGITS_MASK
public static final int DIGITS_MASK
Bit mask for digit shaping options.
DIGITS_NOOP
public static final int DIGITS_NOOP
Digit shaping option: do not perform digit shaping.
DIGIT_TYPE_AN
public static final int DIGIT_TYPE_AN
Digit type option: Use Arabic-Indic digits (U+0660...U+0669).
DIGIT_TYPE_AN_EXTENDED
public static final int DIGIT_TYPE_AN_EXTENDED
Digit type option: Use Eastern (Extended) Arabic-Indic digits (U+06f0...U+06f9).
DIGIT_TYPE_MASK
public static final int DIGIT_TYPE_MASK
Bit mask for digit type options.
LENGTH_FIXED_SPACES_AT_BEGINNING
public static final int LENGTH_FIXED_SPACES_AT_BEGINNING
Memory option: the result must have the same length as the source.
If more room is necessary, then try to consume spaces at the beginning of the text.
LENGTH_FIXED_SPACES_AT_END
public static final int LENGTH_FIXED_SPACES_AT_END
Memory option: the result must have the same length as the source.
If more room is necessary, then try to consume spaces at the end of the text.
LENGTH_FIXED_SPACES_NEAR
public static final int LENGTH_FIXED_SPACES_NEAR
Memory option: the result must have the same length as the source.
If more room is necessary, then try to consume spaces next to modified characters.
LENGTH_GROW_SHRINK
public static final int LENGTH_GROW_SHRINK
Memory option: allow the result to have a different length than the source.
LENGTH_MASK
public static final int LENGTH_MASK
Bit mask for memory options.
LETTERS_MASK
public static final int LETTERS_MASK
Bit mask for letter shaping options.
LETTERS_NOOP
public static final int LETTERS_NOOP
Letter shaping option: do not perform letter shaping.
LETTERS_SHAPE
public static final int LETTERS_SHAPE
Letter shaping option: replace normative letter characters in the U+0600 (Arabic) block,
by shaped ones in the U+FE70 (Presentation Forms B) block. Performs Lam-Alef ligature
substitution.
LETTERS_SHAPE_TASHKEEL_ISOLATED
public static final int LETTERS_SHAPE_TASHKEEL_ISOLATED
Letter shaping option: replace normative letter characters in the U+0600 (Arabic) block,
except for the TASHKEEL characters at U+064B...U+0652, by shaped ones in the U+Fe70
(Presentation Forms B) block. The TASHKEEL characters will always be converted to
the isolated forms rather than to their correct shape.
LETTERS_UNSHAPE
public static final int LETTERS_UNSHAPE
Letter shaping option: replace shaped letter characters in the U+FE70 (Presentation Forms B) block
by normative ones in the U+0600 (Arabic) block. Converts Lam-Alef ligatures to pairs of Lam and
Alef characters, consuming spaces if required.
TEXT_DIRECTION_LOGICAL
public static final int TEXT_DIRECTION_LOGICAL
Direction indicator: the source is in logical (keyboard) order.
TEXT_DIRECTION_MASK
public static final int TEXT_DIRECTION_MASK
Bit mask for direction indicators.
TEXT_DIRECTION_VISUAL_LTR
public static final int TEXT_DIRECTION_VISUAL_LTR
Direction indicator: the source is in visual (display) order, that is,
the leftmost displayed character is stored first.
equals
public boolean equals(Object rhs)
hashCode
public int hashCode()
shape
public String shape(String text)
throws ArabicShapingException
Convert a string, returning the new string.
text
- the string to convert
shape
public void shape(char[] source,
int start,
int length)
throws ArabicShapingException
Convert a range of text in place. This may only be used if the Length option
does not grow or shrink the text.
source
- An array containing the input textstart
- The start of the range of text to convertlength
- The length of the range of text to convert
shape
public int shape(char[] source,
int sourceStart,
int sourceLength,
char[] dest,
int destStart,
int destSize)
throws ArabicShapingException
Convert a range of text in the source array, putting the result
into a range of text in the destination array, and return the number
of characters written.
source
- An array containing the input textsourceStart
- The start of the range of text to convertsourceLength
- The length of the range of text to convertdest
- The destination array that will receive the result.
It may be NULL
only if destSize
is 0.destStart
- The start of the range of the destination buffer to use.destSize
- The size (capacity) of the destination buffer.
If destSize
is 0, then no output is produced,
but the necessary buffer size is returned ("preflighting"). This
does not validate the text against the options, for example,
if letters are being unshaped, and spaces are being consumed
following lamalef, this will not detect a lamalef without a
corresponding space. An error will be thrown when the actual
conversion is attempted.
- The number of chars written to the destination buffer.
If an error occurs, then no output was written, or it may be
incomplete.
toString
public String toString()