gnu.java.awt.font.opentype
Class OpenTypeFont

java.lang.Object
  |
  +--gnu.java.awt.font.opentype.OpenTypeFont

All Implemented Interfaces:

FontDelegate

public final class OpenTypeFont

extends java.lang.Object

implements FontDelegate

A font that takes its data from OpenType or TrueType font tables.

OpenType is an extension of the TrueType font format. In addition to tables for names, kerning or layout, it also stores the shapes of individual glyphs. Three formats are recognized for glyphs: Quadratic splines (classic TrueType), cubic splines (PostScript), and bitmaps.

Author:

Sascha Brawer (brawer@dandelis.ch)

See Also:

Adobe’s OpenType specification, Apple’s TrueType specification

Field Summary

(package private) java.nio.ByteBuffer	buf A buffer containing the font data.
private CharGlyphMap	cmap A delegate object for mapping Unicode UCS-4 codepoints to glyph IDs.
private float	emsPerUnit A factor to convert font units into ems.
private GlyphNamer	glyphNamer A delegate object for providing a name for each glyph.
private java.nio.ByteBuffer	nameTable The font’s name table, or null if this table has not yet been accessed.
(package private) int	numGlyphs The number of glyphs in this font.
private Scaler	scaler The scaler to which the actual scaling work is delegated.
(package private) int[]	tableLength
(package private) int[]	tableStart
(package private) int[]	tableTag
(package private) static int	TAG_OTTO
(package private) static int	TAG_SFNT
(package private) static int	TAG_TRUE
(package private) static int	TAG_TTCF
(package private) static int	TAG_ZAPF
private int	unitsPerEm The number of font units per em.
private int	version The version of the font in 16.16 fixed-point encoding, for example 0x00010000 for version 1.0.

Constructor Summary

(package private)

OpenTypeFont(java.nio.ByteBuffer buf, int offsetTablePosition) Constructs an OpenType or TrueType font.

Method Summary

java.awt.font.GlyphVector	createGlyphVector(java.awt.Font font, java.awt.font.FontRenderContext frc, java.text.CharacterIterator ci) Creates a GlyphVector by mapping each character in a CharacterIterator to the corresponding glyph.
void	getAdvance(int glyphIndex, float pointSize, java.awt.geom.AffineTransform transform, boolean antialias, boolean fractionalMetrics, boolean horizontal, java.awt.geom.Point2D advance) Determines the advance width for a glyph.
float	getAscent(float pointSize, java.awt.geom.AffineTransform transform, boolean antialiased, boolean fractionalMetrics, boolean horizontal) Determines the distance between the base line and the highest ascender.
private CharGlyphMap	getCharGlyphMap()
float	getDescent(float pointSize, java.awt.geom.AffineTransform transform, boolean antialiased, boolean fractionalMetrics, boolean horizontal) Determines the distance between the base line and the lowest descender.
java.lang.String	getFamilyName(java.util.Locale locale) Returns the name of the family to which this font face belongs, for example “Univers”.
java.nio.ByteBuffer	getFontTable(int tag) Creates a view buffer for an OpenType table.
int	getFontTableSize(int tag) Returns the size of one of the tables in the font, or -1 if the table does not exist.
java.lang.String	getFullName(java.util.Locale locale) Returns the full name of this font face, for example “Univers Light”.
int	getGlyph(int ucs4) Looks up a glyph in the font’s cmap tables, without performing any glyph substitution or reordering.
java.lang.String	getGlyphName(int glyphIndex) Returns a name for the specified glyph.
java.awt.geom.GeneralPath	getGlyphOutline(int glyph, float pointSize, java.awt.geom.AffineTransform transform, boolean antialias, boolean fractionalMetrics) Returns the shape of a glyph.
int	getMissingGlyphCode() Returns the index of the glyph which gets displayed if the font cannot map a Unicode code point to a glyph.
private java.lang.String	getName(int name, java.util.Locale locale) Extracts a String from the font’s name table.
int	getNumGlyphs() Returns the number of glyphs in this font face.
java.lang.String	getPostScriptName() Returns the PostScript name of this font face, for example “Univers-Light”.
java.lang.String	getSubFamilyName(java.util.Locale locale) Returns the name of this font face inside the family, for example “Light”.
private int	getTableIndex(int tag) Determines the index of a table into the offset table.
int	getVersion() Returns the version of the font.
(package private) static java.lang.String	tagToString(int tag) Converts a four-byte tag identifier into a String that can be displayed when debugging this class.

Methods inherited from class java.lang.Object

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

Field Detail

TAG_OTTO

static final int TAG_OTTO

See Also:

Constant Field Values

TAG_SFNT

static final int TAG_SFNT

See Also:

Constant Field Values

TAG_TRUE

static final int TAG_TRUE

See Also:

Constant Field Values

TAG_TTCF

static final int TAG_TTCF

See Also:

Constant Field Values

TAG_ZAPF

static final int TAG_ZAPF

See Also:

Constant Field Values

buf

java.nio.ByteBuffer buf

A buffer containing the font data. Note that this may well be an instance of the subclass MappedByteBuffer, in which case the virtual memory subsystem can more efficiently handle requests for font data. This is especially recommended for large font files that contain many glyphs that are rarely accessed.

numGlyphs

final int numGlyphs

The number of glyphs in this font.

tableTag

int[] tableTag

tableStart

int[] tableStart

tableLength

int[] tableLength

version

private int version

The version of the font in 16.16 fixed-point encoding, for example 0x00010000 for version 1.0. There are also two special version IDs used by fonts for Apple Macintosh, namely 'true' (0x74727565) and 'typ1'. OpenType fonts sometimes have 'OTTO' as their version.

unitsPerEm

private int unitsPerEm

The number of font units per em. For fonts with TrueType outlines, this is usually a power of two (such as 2048). For OpenType fonts with PostScript outlines, other values are acceptable (such as 1000).

emsPerUnit

private float emsPerUnit

A factor to convert font units into ems. This value is 1 / unitsPerEm.

scaler

private Scaler scaler

The scaler to which the actual scaling work is delegated.

cmap

private CharGlyphMap cmap

A delegate object for mapping Unicode UCS-4 codepoints to glyph IDs.

glyphNamer

private GlyphNamer glyphNamer

A delegate object for providing a name for each glyph.

nameTable

private java.nio.ByteBuffer nameTable

The font’s name table, or null if this table has not yet been accessed.

Constructor Detail

OpenTypeFont

OpenTypeFont(java.nio.ByteBuffer buf,
             int offsetTablePosition)
       throws java.awt.FontFormatException

Constructs an OpenType or TrueType font.

Parameters:

buf - a buffer with the contents of the font file. It is recommended to use a MappedByteBuffer for very large font files.

offsetTablePosition - the position of the OpenType offset table in the font file. The offset table of most OpenType and TrueType fonts starts at position 0. However, so-called TrueType Collections support multiple OpenType fonts in a single file, which allows sharing some glyphs between fonts. If many glyphs are shared (for example all the Kanji glyphs between multiple Japanese fonts), the space savings can be considerable. In that case, the offset table of each individual font would start at its own position.

Throws:

java.awt.FontFormatException - if the font data is not in OpenType or TrueType format.

Method Detail

getTableIndex

private int getTableIndex(int tag)

Determines the index of a table into the offset table. The result can be used to find the offset and length of a table, as in tableStart[getTableIndex(TAG_NAME)].

Parameters:

tag - the table identifier, for instance OpenType.TAG_NAME.

Returns:

the index of that table into the offset table, or -1 if the font does not contain the table specified by tag.

getFamilyName

public java.lang.String getFamilyName(java.util.Locale locale)

Returns the name of the family to which this font face belongs, for example “Univers”.

Specified by:

getFamilyName in interface FontDelegate

Parameters:

locale - the locale for which to localize the name.

Returns:

the family name.

getSubFamilyName

public java.lang.String getSubFamilyName(java.util.Locale locale)

Returns the name of this font face inside the family, for example “Light”.

Specified by:

getSubFamilyName in interface FontDelegate

Parameters:

locale - the locale for which to localize the name.

Returns:

the name of the face inside its family.

getFullName

public java.lang.String getFullName(java.util.Locale locale)

Returns the full name of this font face, for example “Univers Light”.

Specified by:

getFullName in interface FontDelegate

Parameters:

locale - the locale for which to localize the name.

Returns:

the face name.

getPostScriptName

public java.lang.String getPostScriptName()

Returns the PostScript name of this font face, for example “Univers-Light”.

Specified by:

getPostScriptName in interface FontDelegate

Returns:

the PostScript name, or null if the font does not provide a PostScript name.

getNumGlyphs

public int getNumGlyphs()

Returns the number of glyphs in this font face.

Specified by:

getNumGlyphs in interface FontDelegate

getMissingGlyphCode

public int getMissingGlyphCode()

Returns the index of the glyph which gets displayed if the font cannot map a Unicode code point to a glyph. Many fonts show this glyph as an empty box.

Specified by:

getMissingGlyphCode in interface FontDelegate

getName

private java.lang.String getName(int name,
                                 java.util.Locale locale)

Extracts a String from the font’s name table.

Parameters:

name - the numeric TrueType or OpenType name ID.

locale - the locale for which names shall be localized, or null if the locale does mot matter because the name is known to be language-independent (for example, because it is the PostScript name).

getVersion

public int getVersion()

Returns the version of the font.

Returns:

the version in 16.16 fixed-point encoding, for example 0x00010000 for version 1.0.

See Also:

OpenType.getVersion()

getFontTable

public java.nio.ByteBuffer getFontTable(int tag)

Creates a view buffer for an OpenType table. The caller can access the returned buffer without needing to synchronize access from multiple threads.

Parameters:

tag - the table identifier, for example OpenType.GLYF.

Returns:

a slice of the underlying buffer containing the table, or null if the font does not contain the requested table.

getFontTableSize

public int getFontTableSize(int tag)

Returns the size of one of the tables in the font, or -1 if the table does not exist.

getCharGlyphMap

private CharGlyphMap getCharGlyphMap()

getGlyph

public int getGlyph(int ucs4)

Looks up a glyph in the font’s cmap tables, without performing any glyph substitution or reordering. Because of this limitation, this method cannot be used for script systems that need advanced glyph mapping, such as Arabic, Korean, or even Latin with exotic accents.

It is safe to call this method from any thread.

Parameters:

ucs4 - the Unicode codepoint in the 32-bit Unicode character set UCS-4. Because UTF-16 surrogates do not correspond to a single glyph, it does not make sense to pass them here.

Returns:

the glyph index, or zero if the font does not contain a glyph for the specified codepoint.

createGlyphVector

public java.awt.font.GlyphVector createGlyphVector(java.awt.Font font,
                                                   java.awt.font.FontRenderContext frc,
                                                   java.text.CharacterIterator ci)

Creates a GlyphVector by mapping each character in a CharacterIterator to the corresponding glyph.

The mapping takes only the font’s cmap tables into consideration. No other operations (such as glyph re-ordering, composition, or ligature substitution) are performed. This means that the resulting GlyphVector will not be correct for text in languages that have complex character-to-glyph mappings, such as Arabic, Hebrew, Hindi, or Thai.

Specified by:

createGlyphVector in interface FontDelegate

Parameters:

font - the font object that the created GlyphVector will return when it gets asked for its font. This argument is needed because the public API works with java.awt.Font, not with some private delegate like OpenTypeFont.

frc - the font rendering parameters that are used for measuring glyphs. The exact placement of text slightly depends on device-specific characteristics, for instance the device resolution or anti-aliasing. For this reason, any measurements will only be accurate if the passed FontRenderContext correctly reflects the relevant parameters. Hence, frc should be obtained from the same Graphics2D that will be used for drawing, and any rendering hints should be set to the desired values before obtaining frc.

ci - a CharacterIterator for iterating over the characters to be displayed.

getAdvance

public void getAdvance(int glyphIndex,
                       float pointSize,
                       java.awt.geom.AffineTransform transform,
                       boolean antialias,
                       boolean fractionalMetrics,
                       boolean horizontal,
                       java.awt.geom.Point2D advance)

Determines the advance width for a glyph.

Specified by:

getAdvance in interface FontDelegate

Parameters:

glyphIndex - the glyph whose advance width is to be determined.

pointSize - the point size of the font.

transform - a transform that is applied in addition to scaling to the specified point size. This is often used for scaling according to the device resolution. Those who lack any aesthetic sense may also use the transform to slant or stretch glyphs.

antialias - true for anti-aliased rendering, false for normal rendering. For hinted fonts, this parameter may indeed affect the result.

fractionalMetrics - true for fractional metrics, false for rounding the result to a pixel boundary.

horizontal - true for horizontal line layout, false for vertical line layout.

advance - a point whose x and y fields will hold the advance in each direction. It is possible that both values are non-zero, for example if transform is a rotation, or in the case of Urdu fonts.

getGlyphOutline

public java.awt.geom.GeneralPath getGlyphOutline(int glyph,
                                                 float pointSize,
                                                 java.awt.geom.AffineTransform transform,
                                                 boolean antialias,
                                                 boolean fractionalMetrics)

Returns the shape of a glyph.

Specified by:

getGlyphOutline in interface FontDelegate

Parameters:

pointSize - the point size of the font.

transform - a transform that is applied in addition to scaling to the specified point size. This is often used for scaling according to the device resolution. Those who lack any aesthetic sense may also use the transform to slant or stretch glyphs.

antialias - true for anti-aliased rendering, false for normal rendering. For hinted fonts, this parameter may indeed affect the result.

fractionalMetrics - true for fractional metrics, false for rounding the result to a pixel boundary.

glyph - the glyph whose advance width is to be determined.

Returns:

the scaled and grid-fitted outline of the specified glyph, or null for bitmap fonts.

getGlyphName

public java.lang.String getGlyphName(int glyphIndex)

Returns a name for the specified glyph. This is useful for generating PostScript or PDF files that embed some glyphs of a font.

Names are not unique: Under some rare circumstances, the same name can be returned for different glyphs. It is therefore recommended that printer drivers check whether the same name has already been returned for antoher glyph, and make the name unique by adding the string ".alt" followed by the glyph index.

This situation would occur for an OpenType or TrueType font that has a post table of format 3 and provides a mapping from glyph IDs to Unicode sequences through a Zapf table. If the same sequence of Unicode codepoints leads to different glyphs (depending on contextual position, for example, or on typographic sophistication level), the same name would get synthesized for those glyphs.

Specified by:

getGlyphName in interface FontDelegate

Parameters:

glyphIndex - the glyph whose name the caller wants to retrieve.

getAscent

public float getAscent(float pointSize,
                       java.awt.geom.AffineTransform transform,
                       boolean antialiased,
                       boolean fractionalMetrics,
                       boolean horizontal)

Determines the distance between the base line and the highest ascender.

Specified by:

getAscent in interface FontDelegate

Parameters:

pointSize - the point size of the font.

transform - a transform that is applied in addition to scaling to the specified point size. This is often used for scaling according to the device resolution. Those who lack any aesthetic sense may also use the transform to slant or stretch glyphs.

fractionalMetrics - true for fractional metrics, false for rounding the result to a pixel boundary.

horizontal - true for horizontal line layout, false for vertical line layout.

Returns:

the ascent, which usually is a positive number.

getDescent

public float getDescent(float pointSize,
                        java.awt.geom.AffineTransform transform,
                        boolean antialiased,
                        boolean fractionalMetrics,
                        boolean horizontal)

Determines the distance between the base line and the lowest descender.

Specified by:

getDescent in interface FontDelegate

Parameters:

pointSize - the point size of the font.

transform - a transform that is applied in addition to scaling to the specified point size. This is often used for scaling according to the device resolution. Those who lack any aesthetic sense may also use the transform to slant or stretch glyphs.

fractionalMetrics - true for fractional metrics, false for rounding the result to a pixel boundary.

horizontal - true for horizontal line layout, false for vertical line layout.

Returns:

the descent, which usually is a nagative number.

tagToString

static java.lang.String tagToString(int tag)

Converts a four-byte tag identifier into a String that can be displayed when debugging this class.

Parameters:

tag - the tag as an int.

Returns:

the tag in human-readable form, for example name or glyf.