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PDFBOX-5729: add GSUB worker for Gujarati, by JAVAUSER
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git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1914529 13f79535-47bb-0310-9956-ffa450edef68
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@THausherr
THausherr committed Dec 11, 2023
1 parent 2312a51 commit fc8b24c
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265 changes: 265 additions & 0 deletions fontbox/src/main/java/org/apache/fontbox/ttf/gsub/GsubWorkerForGujarati.java
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.apache.fontbox.ttf.gsub;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import org.apache.fontbox.ttf.CmapLookup;
import org.apache.fontbox.ttf.model.GsubData;
import org.apache.fontbox.ttf.model.ScriptFeature;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
*
* Gujarati-specific implementation of GSUB system.
*
* @author JAVAUSER
*
*/
public class GsubWorkerForGujarati implements GsubWorker
{
private static final Logger LOG = LogManager.getLogger(GsubWorkerForGujarati.class);

private static final String RKRF_FEATURE = "rkrf";
private static final String VATU_FEATURE = "vatu";

/**
* This sequence is very important. This has been taken from <a href=
* "https://docs.microsoft.com/en-us/typography/script-development/gujarati">https://docs.microsoft.com/en-us/typography/script-development/gujarati</a>
*/
private static final List<String> FEATURES_IN_ORDER = Arrays.asList("locl", "nukt", "akhn",
"rphf", RKRF_FEATURE,"blwf", "half", VATU_FEATURE, "cjct", "pres", "abvs", "blws",
"psts", "haln", "calt");

// Reph glyphs
private static final char[] REPH_CHARS = {'\u0AB0', '\u0ACD'};
// Glyphs to precede reph
private static final char[] BEFORE_REPH_CHARS={'\u0ABE','\u0AC0'};

// Gujarati vowel sign I
private static final char BEFORE_HALF_CHAR = '\u0ABF';

private final CmapLookup cmapLookup;
private final GsubData gsubData;

private final List<Integer> rephGlyphIds;
private final List<Integer> beforeRephGlyphIds;
private final List<Integer> beforeHalfGlyphIds;

GsubWorkerForGujarati(CmapLookup cmapLookup, GsubData gsubData)
{
this.cmapLookup = cmapLookup;
this.gsubData = gsubData;
beforeHalfGlyphIds = getBeforeHalfGlyphIds();
rephGlyphIds = getRephGlyphIds();
beforeRephGlyphIds=getbeforeRephGlyphIds();
}

@Override
public List<Integer> applyTransforms(List<Integer> originalGlyphIds)
{
List<Integer> intermediateGlyphsFromGsub = adjustRephPosition(originalGlyphIds);
intermediateGlyphsFromGsub = repositionGlyphs(intermediateGlyphsFromGsub);
for (String feature : FEATURES_IN_ORDER)
{
if (!gsubData.isFeatureSupported(feature))
{
if (feature.equals(RKRF_FEATURE) && gsubData.isFeatureSupported(VATU_FEATURE))
{
// Create your own rkrf feature from vatu feature
intermediateGlyphsFromGsub = applyRKRFFeature(
gsubData.getFeature(VATU_FEATURE),
intermediateGlyphsFromGsub);
}
LOG.debug("the feature {} was not found", feature);
continue;
}
LOG.debug("applying the feature {}", feature);
ScriptFeature scriptFeature = gsubData.getFeature(feature);
intermediateGlyphsFromGsub = applyGsubFeature(scriptFeature,
intermediateGlyphsFromGsub);
}
return Collections.unmodifiableList(intermediateGlyphsFromGsub);
}

private List<Integer> applyRKRFFeature(ScriptFeature rkrfGlyphsForSubstitution,
List<Integer> originalGlyphIds)
{
Set<List<Integer>> rkrfGlyphIds = rkrfGlyphsForSubstitution.getAllGlyphIdsForSubstitution();
if (rkrfGlyphIds.isEmpty())
{
LOG.debug("Glyph substitution list for {} is empty.", rkrfGlyphsForSubstitution.getName());
return originalGlyphIds;
}

// Replace this with better implementation to get second GlyphId from rkrfGlyphIds
int rkrfReplacement = 0;
for (List<Integer> firstList : rkrfGlyphIds)
{
if (firstList.size() > 1)
{
rkrfReplacement = firstList.get(1);
break;
}
}
if (rkrfReplacement == 0)
{
LOG.debug("Cannot find rkrf candidate. The rkrfGlyphIds doesn't contain lists of two elements.");
return originalGlyphIds;
}

List<Integer> rkrfList = new ArrayList<>(originalGlyphIds);
for (int index = originalGlyphIds.size() - 1; index > 1; index--)
{
int raGlyph = originalGlyphIds.get(index);
if (raGlyph == rephGlyphIds.get(0))
{
int viramaGlyph = originalGlyphIds.get(index - 1);
if (viramaGlyph == rephGlyphIds.get(1))
{
rkrfList.set(index - 1, rkrfReplacement);
rkrfList.remove(index);
}
}
}
return rkrfList;
}

private List<Integer> repositionGlyphs(List<Integer> originalGlyphIds)
{
List<Integer> repositionedGlyphIds = new ArrayList<>(originalGlyphIds);
int listSize = repositionedGlyphIds.size();
int foundIndex = listSize - 1;
int nextIndex = listSize - 2;
while (nextIndex > -1)
{
int glyph = repositionedGlyphIds.get(foundIndex);
int prevIndex = foundIndex + 1;
if (beforeHalfGlyphIds.contains(glyph))
{
repositionedGlyphIds.remove(foundIndex);
repositionedGlyphIds.add(nextIndex--, glyph);
}
else if (rephGlyphIds.get(1).equals(glyph) && prevIndex < listSize)
{
int prevGlyph = repositionedGlyphIds.get(prevIndex);
if (beforeHalfGlyphIds.contains(prevGlyph))
{
repositionedGlyphIds.remove(prevIndex);
repositionedGlyphIds.add(nextIndex--, prevGlyph);
}
}
foundIndex = nextIndex--;
}
return repositionedGlyphIds;
}

private List<Integer> adjustRephPosition(List<Integer> originalGlyphIds)
{
List<Integer> rephAdjustedList = new ArrayList<>(originalGlyphIds);
for (int index = 0; index < originalGlyphIds.size() - 2; index++)
{
int raGlyph = originalGlyphIds.get(index);
int viramaGlyph = originalGlyphIds.get(index + 1);
if (raGlyph == rephGlyphIds.get(0) && viramaGlyph == rephGlyphIds.get(1))
{
int nextConsonantGlyph = originalGlyphIds.get(index + 2);
rephAdjustedList.set(index, nextConsonantGlyph);
rephAdjustedList.set(index + 1, raGlyph);
rephAdjustedList.set(index + 2, viramaGlyph);

if (index + 3 < originalGlyphIds.size())
{
int matraGlyph = originalGlyphIds.get(index + 3);
if (beforeRephGlyphIds.contains(matraGlyph))
{
rephAdjustedList.set(index + 1, matraGlyph);
rephAdjustedList.set(index + 2, raGlyph);
rephAdjustedList.set(index + 3, viramaGlyph);
}
}
}
}
return rephAdjustedList;
}

private List<Integer> applyGsubFeature(ScriptFeature scriptFeature, List<Integer> originalGlyphs)
{
Set<List<Integer>> allGlyphIdsForSubstitution = scriptFeature.getAllGlyphIdsForSubstitution();
if (allGlyphIdsForSubstitution.isEmpty())
{
LOG.debug("getAllGlyphIdsForSubstitution() for {} is empty", scriptFeature.getName());
return originalGlyphs;
}
GlyphArraySplitter glyphArraySplitter = new GlyphArraySplitterRegexImpl(
allGlyphIdsForSubstitution);
List<List<Integer>> tokens = glyphArraySplitter.split(originalGlyphs);
List<Integer> gsubProcessedGlyphs = new ArrayList<>(tokens.size());
tokens.forEach(chunk ->
{
if (scriptFeature.canReplaceGlyphs(chunk))
{
Integer glyphId = scriptFeature.getReplacementForGlyphs(chunk);
gsubProcessedGlyphs.add(glyphId);
}
else
{
gsubProcessedGlyphs.addAll(chunk);
}
});
LOG.debug("originalGlyphs: {}, gsubProcessedGlyphs: {}", originalGlyphs, gsubProcessedGlyphs);
return gsubProcessedGlyphs;
}

private List<Integer> getBeforeHalfGlyphIds()
{
List<Integer> glyphIds = new ArrayList<>();
glyphIds.add(getGlyphId(BEFORE_HALF_CHAR));
return Collections.unmodifiableList(glyphIds);
}

private List<Integer> getRephGlyphIds()
{
List<Integer> result = new ArrayList<>();
for (char character : REPH_CHARS)
{
result.add(getGlyphId(character));
}
return Collections.unmodifiableList(result);
}

private List<Integer> getbeforeRephGlyphIds()
{
List<Integer> glyphIds = new ArrayList<>();
for (char character : BEFORE_REPH_CHARS)
{
glyphIds.add(getGlyphId(character));
}
return Collections.unmodifiableList(glyphIds);
}

private Integer getGlyphId(char character)
{
return cmapLookup.getGlyphId(character);
}
}

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