/*
*
* This file is part of the iText (R) project.
Copyright (c) 1998-2017 iText Group NV
* Authors: Ram Narayan, Bruno Lowagie, et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License version 3
* as published by the Free Software Foundation with the addition of the
* following permission added to Section 15 as permitted in Section 7(a):
* FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
* ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
* OF THIRD PARTY RIGHTS
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Affero General Public License for more details.
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, see http://www.gnu.org/licenses or write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA, 02110-1301 USA, or download the license from the following URL:
* http://itextpdf.com/terms-of-use/
*
* The interactive user interfaces in modified source and object code versions
* of this program must display Appropriate Legal Notices, as required under
* Section 5 of the GNU Affero General Public License.
*
* In accordance with Section 7(b) of the GNU Affero General Public License,
* a covered work must retain the producer line in every PDF that is created
* or manipulated using iText.
*
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the iText software without
* disclosing the source code of your own applications.
* These activities include: offering paid services to customers as an ASP,
* serving PDFs on the fly in a web application, shipping iText with a closed
* source product.
*
* For more information, please contact iText Software Corp. at this
* address: sales@itextpdf.com
*/
package com.itextpdf.text.pdf.languages;
/**
* Superclass for processors that can convert a String of bytes in an Indic
* language to a String in the same language of which the bytes are reordered
* for rendering using a font that contains the necessary glyphs.
*/
public abstract class IndicLigaturizer implements LanguageProcessor {
// Hashtable Indexes
public static final int MATRA_AA = 0;
public static final int MATRA_I = 1;
public static final int MATRA_E = 2;
public static final int MATRA_AI = 3;
public static final int MATRA_HLR = 4;
public static final int MATRA_HLRR = 5;
public static final int LETTER_A = 6;
public static final int LETTER_AU = 7;
public static final int LETTER_KA = 8;
public static final int LETTER_HA = 9;
public static final int HALANTA = 10;
/**
* The table mapping specific character indexes to the characters in a
* specific language.
*/
protected char[] langTable;
/**
* Reorders the bytes in a String making Indic ligatures
*
* @param s
* the original String
* @return the ligaturized String
*/
public String process(String s) {
if (s == null || s.length() == 0)
return "";
StringBuilder res = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char letter = s.charAt(i);
if (IsVyanjana(letter) || IsSwaraLetter(letter)) {
res.append(letter);
} else if (IsSwaraMatra(letter)) {
int prevCharIndex = res.length() - 1;
if (prevCharIndex >= 0) {
// a Halanta followed by swara matra, causes it to lose its
// identity
if (res.charAt(prevCharIndex) == langTable[HALANTA])
res.deleteCharAt(prevCharIndex);
res.append(letter);
int prevPrevCharIndex = res.length() - 2;
if (letter == langTable[MATRA_I] && prevPrevCharIndex >= 0)
swap(res, prevPrevCharIndex, res.length() - 1);
} else {
res.append(letter);
}
} else {
res.append(letter);
}
}
return res.toString();
}
/**
* Indic languages are written from right to left.
*
* @return false
* @see com.itextpdf.text.pdf.languages.LanguageProcessor#isRTL()
*/
public boolean isRTL() {
return false;
}
/**
* Checks if a character is vowel letter.
*
* @param ch
* the character that needs to be checked
* @return true if the characters is a vowel letter
*/
protected boolean IsSwaraLetter(char ch) {
return (ch >= langTable[LETTER_A] && ch <= langTable[LETTER_AU]);
}
/**
* Checks if a character is vowel sign.
*
* @param ch
* the character that needs to be checked
* @return true if the characters is a vowel sign
*/
protected boolean IsSwaraMatra(char ch) {
return ((ch >= langTable[MATRA_AA] && ch <= langTable[MATRA_AI])
|| ch == langTable[MATRA_HLR] || ch == langTable[MATRA_HLRR]);
}
/**
* Checks if a character is consonant letter.
*
* @param ch
* the character that needs to be checked
* @return true if the chracter is a consonant letter
*/
protected boolean IsVyanjana(char ch) {
return (ch >= langTable[LETTER_KA] && ch <= langTable[LETTER_HA]);
}
/**
* Swaps two characters in a StringBuilder object
*
* @param s
* the StringBuilder
* @param i
* the index of one character
* @param j
* the index of the other character
*/
private static void swap(StringBuilder s, int i, int j) {
char temp = s.charAt(i);
s.setCharAt(i, s.charAt(j));
s.setCharAt(j, temp);
}
}