Package org.apache.fontbox.ttf

Class GlyphSubstitutionTable

java.lang.Object

org.apache.fontbox.ttf.TTFTable

org.apache.fontbox.ttf.GlyphSubstitutionTable

public class GlyphSubstitutionTable
extends TTFTable

A glyph substitution 'GSUB' table in a TrueType or OpenType font.

Field Summary

Fields

Modifier and Type	Field	Description
private FeatureListTable	featureListTable
private GsubData	gsubData
private String	lastUsedSupportedScript
private static final org.apache.commons.logging.Log	LOG
private final Map<Integer,Integer>	lookupCache
private LookupListTable	lookupListTable
private final Map<Integer,Integer>	reverseLookup
private Map<String,ScriptTable>	scriptList
static final String	TAG
private static final Pattern	WORDPATTERN	The regex represents 4 'word characters' [a-zA-Z_0-9], see ASCII.WORD.

Fields inherited from class org.apache.fontbox.ttf.TTFTable

initialized

Constructor Summary

Constructors

Constructor	Description
GlyphSubstitutionTable()

Method Summary

Modifier and Type	Method	Description
private int	applyFeature(FeatureRecord featureRecord, int gid)
private boolean	containsFeature(List<FeatureRecord> featureRecords, String featureTag)
private int	doLookup(LookupTable lookupTable, int gid)
private List<FeatureRecord>	getFeatureRecords(Collection<LangSysTable> langSysTables, List<String> enabledFeatures)	Get a list of FeatureRecords from a collection of LangSysTables.
GsubData	getGsubData()	Returns a GsubData instance containing all scripts of the table.
GsubData	getGsubData(String scriptTag)	Builds a new GsubData instance for given script tag.
private Collection<LangSysTable>	getLangSysTables(String scriptTag)
int	getSubstitution(int gid, String[] scriptTags, List<String> enabledFeatures)	Apply glyph substitutions to the supplied gid.
Set<String>	getSupportedScriptTags()
int	getUnsubstitution(int sgid)	For a substitute-gid (obtained from getSubstitution(int, String[], List)), retrieve the original gid.
(package private) void	read(TrueTypeFont ttf, TTFDataStream data)	This will read the required data from the stream.
private LookupSubTable	readAlternateSubstitutionSubtable(TTFDataStream data, long offset)
private CoverageTable	readCoverageTable(TTFDataStream data, long offset)
private FeatureListTable	readFeatureList(TTFDataStream data, long offset)
private FeatureTable	readFeatureTable(TTFDataStream data, long offset)
private LangSysTable	readLangSysTable(TTFDataStream data, long offset)
private LigatureSetTable	readLigatureSetTable(TTFDataStream data, long ligatureSetTableLocation, int coverageGlyphId)
private LookupSubTable	readLigatureSubstitutionSubtable(TTFDataStream data, long offset)
private LigatureTable	readLigatureTable(TTFDataStream data, long ligatureTableLocation, int coverageGlyphId)
private LookupListTable	readLookupList(TTFDataStream data, long offset)
private LookupSubTable	readLookupSubtable(TTFDataStream data, long offset, int lookupType)
private LookupTable	readLookupTable(TTFDataStream data, long offset)
private LookupSubTable	readMultipleSubstitutionSubtable(TTFDataStream data, long offset)
private RangeRecord	readRangeRecord(TTFDataStream data)
private Map<String,ScriptTable>	readScriptList(TTFDataStream data, long offset)
private ScriptTable	readScriptTable(TTFDataStream data, long offset)
private LookupSubTable	readSingleLookupSubTable(TTFDataStream data, long offset)
private void	removeFeature(List<FeatureRecord> featureRecords, String featureTag)
private String	selectScriptTag(String[] tags)	Choose from one of the supplied OpenType script tags, depending on what the font supports and potentially on context.

Methods inherited from class org.apache.fontbox.ttf.TTFTable

getCheckSum, getInitialized, getLength, getOffset, getTag, readHeaders, setCheckSum, setLength, setOffset, setTag

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

LOG

private static final org.apache.commons.logging.Log LOG

TAG

public static final String TAG

See Also:

• Constant Field Values

scriptList

private Map<String,ScriptTable> scriptList

featureListTable

private FeatureListTable featureListTable

lookupListTable

private LookupListTable lookupListTable

lookupCache

private final Map<Integer,Integer> lookupCache

reverseLookup

private final Map<Integer,Integer> reverseLookup

lastUsedSupportedScript

private String lastUsedSupportedScript

gsubData

private GsubData gsubData

WORDPATTERN

private static final Pattern WORDPATTERN

The regex represents 4 'word characters' [a-zA-Z_0-9], see ASCII.WORD.

Note: the ' '-character is not matched!

Constructor Details

GlyphSubstitutionTable

GlyphSubstitutionTable()

Method Details

read

void read(TrueTypeFont ttf,
 TTFDataStream data)
   throws IOException

Description copied from class: TTFTable

This will read the required data from the stream.

Overrides:

read in class TTFTable

Parameters:

ttf - The font that is being read.

data - The stream to read the data from.

Throws:

IOException - If there is an error reading the data.

readScriptList

private Map<String,ScriptTable> readScriptList(TTFDataStream data,
 long offset)
                                        throws IOException

Throws:

IOException

readScriptTable

private ScriptTable readScriptTable(TTFDataStream data,
 long offset)
                             throws IOException

Throws:

IOException

readLangSysTable

private LangSysTable readLangSysTable(TTFDataStream data,
 long offset)
                               throws IOException

Throws:

IOException

readFeatureList

private FeatureListTable readFeatureList(TTFDataStream data,
 long offset)
                                  throws IOException

Throws:

IOException

readFeatureTable

private FeatureTable readFeatureTable(TTFDataStream data,
 long offset)
                               throws IOException

Throws:

IOException

readLookupList

private LookupListTable readLookupList(TTFDataStream data,
 long offset)
                                throws IOException

Throws:

IOException

readLookupSubtable

private LookupSubTable readLookupSubtable(TTFDataStream data,
 long offset,
 int lookupType)
                                   throws IOException

Throws:

IOException

readLookupTable

private LookupTable readLookupTable(TTFDataStream data,
 long offset)
                             throws IOException

Throws:

IOException

readSingleLookupSubTable

private LookupSubTable readSingleLookupSubTable(TTFDataStream data,
 long offset)
                                         throws IOException

Throws:

IOException

readMultipleSubstitutionSubtable

private LookupSubTable readMultipleSubstitutionSubtable(TTFDataStream data,
 long offset)
                                                 throws IOException

Throws:

IOException

readAlternateSubstitutionSubtable

private LookupSubTable readAlternateSubstitutionSubtable(TTFDataStream data,
 long offset)
                                                  throws IOException

Throws:

IOException

readLigatureSubstitutionSubtable

private LookupSubTable readLigatureSubstitutionSubtable(TTFDataStream data,
 long offset)
                                                 throws IOException

Throws:

IOException

readLigatureSetTable

private LigatureSetTable readLigatureSetTable(TTFDataStream data,
 long ligatureSetTableLocation,
 int coverageGlyphId)
                                       throws IOException

Throws:

IOException

readLigatureTable

private LigatureTable readLigatureTable(TTFDataStream data,
 long ligatureTableLocation,
 int coverageGlyphId)
                                 throws IOException

Throws:

IOException

readCoverageTable

private CoverageTable readCoverageTable(TTFDataStream data,
 long offset)
                                 throws IOException

Throws:

IOException

selectScriptTag

private String selectScriptTag(String[] tags)

Choose from one of the supplied OpenType script tags, depending on what the font supports and potentially on context.

Parameters:

tags -

Returns:

The best OpenType script tag

getLangSysTables

private Collection<LangSysTable> getLangSysTables(String scriptTag)

getFeatureRecords

private List<FeatureRecord> getFeatureRecords(Collection<LangSysTable> langSysTables,
 List<String> enabledFeatures)

Get a list of FeatureRecords from a collection of LangSysTables. Optionally filter the returned features by supplying a list of allowed feature tags in enabledFeatures. Note that features listed as required (LangSysTable#requiredFeatureIndex) will be included even if not explicitly enabled.

Parameters:

langSysTables - The LangSysTables indicating FeatureRecords to search for

enabledFeatures - An optional list of feature tags (null to allow all)

Returns:

The indicated FeatureRecords

containsFeature

private boolean containsFeature(List<FeatureRecord> featureRecords,
 String featureTag)

removeFeature

private void removeFeature(List<FeatureRecord> featureRecords,
 String featureTag)

applyFeature

private int applyFeature(FeatureRecord featureRecord,
 int gid)

doLookup

private int doLookup(LookupTable lookupTable,
 int gid)

getSubstitution

public int getSubstitution(int gid,
 String[] scriptTags,
 List<String> enabledFeatures)

Apply glyph substitutions to the supplied gid. The applicable substitutions are determined by the scriptTags which indicate the language of the gid, and by the list of enabledFeatures. To ensure that a single gid isn't mapped to multiple substitutions, subsequent invocations with the same gid will return the same result as the first, regardless of script or enabled features.

Parameters:

gid - GID

scriptTags - Script tags applicable to the gid (see OpenTypeScript)

enabledFeatures - list of features to apply

Returns:

the id of the glyph substitution

getUnsubstitution

public int getUnsubstitution(int sgid)

For a substitute-gid (obtained from getSubstitution(int, String[], List)), retrieve the original gid.

Only gids previously substituted by this instance can be un-substituted. If you are trying to unsubstitute before you substitute, something is wrong.

Parameters:

sgid - Substitute GID

Returns:

the original gid of a substitute-gid

getGsubData

public GsubData getGsubData()

Returns a GsubData instance containing all scripts of the table.

Returns:

the GsubData instance representing the table

getGsubData

public GsubData getGsubData(String scriptTag)

Builds a new GsubData instance for given script tag. In contrast to neighbour getGsubData() method, this one does not try to find the first supported language and load GSUB data for it. Instead, it fetches the data for the given scriptTag (if it's supported by the font) leaving the language unspecified. It means that even after successful reading of GSUB data, the actual glyph substitution may not work if there is no corresponding GsubWorker implementation for it. Note: This method performs searching on every invocation (no results are cached)

Parameters:

scriptTag - a script tag for which the data is needed

Returns:

GSUB data for the given script or null if no such script in the font

getSupportedScriptTags

public Set<String> getSupportedScriptTags()

Returns:

a read-only view of the script tags for which this GSUB table has records

readRangeRecord

private RangeRecord readRangeRecord(TTFDataStream data)
                             throws IOException

Throws:

IOException