The Font class represents fonts, which are used to
render text in a visible way.
A font provides the information needed to map sequences of
characters to sequences of glyphs
and to render sequences of glyphs on Graphics and
Component objects.
Characters and Glyphs
A character is a symbol that represents an item such as a letter,
a digit, or punctuation in an abstract way. For example, 'g',
LATIN SMALL LETTER G, is a character.
A glyph is a shape used to render a character or a sequence of
characters. In simple writing systems, such as Latin, typically one glyph
represents one character. In general, however, characters and glyphs do not
have one-to-one correspondence. For example, the character 'á'
LATIN SMALL LETTER A WITH ACUTE, can be represented by
two glyphs: one for 'a' and one for '´'. On the other hand, the
two-character string "fi" can be represented by a single glyph, an
"fi" ligature. In complex writing systems, such as Arabic or the South
and South-East Asian writing systems, the relationship between characters
and glyphs can be more complicated and involve context-dependent selection
of glyphs as well as glyph reordering.
A font encapsulates the collection of glyphs needed to render a selected set
of characters as well as the tables needed to map sequences of characters to
corresponding sequences of glyphs.
Physical and Logical Fonts
The Java 2 platform distinguishes between two kinds of fonts:
physical fonts and logical fonts.
Physical fonts are the actual font libraries containing glyph data
and tables to map from character sequences to glyph sequences, using a font
technology such as TrueType or PostScript Type 1.
All implementations of the Java 2 platform must support TrueType fonts;
support for other font technologies is implementation dependent.
Physical fonts may use names such as Helvetica, Palatino, HonMincho, or
any number of other font names.
Typically, each physical font supports only a limited set of writing
systems, for example, only Latin characters or only Japanese and Basic
Latin.
The set of available physical fonts varies between configurations.
Applications that require specific fonts can bundle them and instantiate
them using the createFont method.
Logical fonts are the five font families defined by the Java
platform which must be supported by any Java runtime environment:
Serif, SansSerif, Monospaced, Dialog, and DialogInput.
These logical fonts are not actual font libraries. Instead, the logical
font names are mapped to physical fonts by the Java runtime environment.
The mapping is implementation and usually locale dependent, so the look
and the metrics provided by them vary.
Typically, each logical font name maps to several physical fonts in order to
cover a large range of characters.
Peered AWT components, such as Label and
TextField, can only use logical fonts.
For a discussion of the relative advantages and disadvantages of using
physical or logical fonts, see the
Internationalization FAQ
document.
Font Faces and Names
A Font
can have many faces, such as heavy, medium, oblique, gothic and
regular. All of these faces have similar typographic design.
There are three different names that you can get from a
Font object. The logical font name is simply the
name that was used to construct the font.
The font face name, or just font name for
short, is the name of a particular font face, like Helvetica Bold. The
family name is the name of the font family that determines the
typographic design across several faces, like Helvetica.
The Font class represents an instance of a font face from
a collection of font faces that are present in the system resources
of the host system. As examples, Arial Bold and Courier Bold Italic
are font faces. There can be several Font objects
associated with a font face, each differing in size, style, transform
and font features.
The getAllFonts method
of the GraphicsEnvironment class returns an
array of all font faces available in the system. These font faces are
returned as Font objects with a size of 1, identity
transform and default font features. These
base fonts can then be used to derive new Font objects
with varying sizes, styles, transforms and font features via the
deriveFont methods in this class.
Class Variables
PLAIN public static final int
The plain style constant.
BOLD public static final int
The bold style constant. This can be combined with the other style
constants (except PLAIN) for mixed styles.
ITALIC public static final int
The italicized style constant. This can be combined with the other
style constants (except PLAIN) for mixed styles.
ROMAN_BASELINE public static final int
The baseline used in most Roman scripts when laying out text.
CENTER_BASELINE public static final int
The baseline used in ideographic scripts like Chinese, Japanese,
and Korean when laying out text.
HANGING_BASELINE public static final int
The baseline used in Devanigiri and similar scripts when laying
out text.
TRUETYPE_FONT public static final int
Create a Font of type TRUETYPE.
In future other types may be added to support other font types.
LAYOUT_LEFT_TO_RIGHT public static final int
A flag to layoutGlyphVector indicating that text is left-to-right as
determined by Bidi analysis.
LAYOUT_RIGHT_TO_LEFT public static final int
A flag to layoutGlyphVector indicating that text is right-to-left as
determined by Bidi analysis.
LAYOUT_NO_START_CONTEXT public static final int
A flag to layoutGlyphVector indicating that text in the char array
before the indicated start should not be examined.
LAYOUT_NO_LIMIT_CONTEXT public static final int
A flag to layoutGlyphVector indicating that text in the char array
after the indicated limit should not be examined.
Creates a new Font with the specified attributes.
This Font only recognizes keys defined in
TextAttribute as attributes. If attributes
is null, a new Font is initialized
with default attributes.
Font
public Font(
Stringname,
int style,
int size
)
Creates a new Font from the specified name, style and
point size.
Returns a new Font with the specified font type
and input data. The new Font is
created with a point size of 1 and style PLAIN.
This base font can then be used with the deriveFont
methods in this class to derive new Font objects with
varying sizes, styles, transforms and font features. This
method does not close the InputStream.
Returns the Font that the str
argument describes.
To ensure that this method returns the desired Font,
format the str parameter in
one of two ways:
"fontfamilyname-style-pointsize" or
"fontfamilyname style pointsize"
in which style is one of the three
case-insensitive strings:
"BOLD", "BOLDITALIC", or
"ITALIC", and pointsize is a decimal
representation of the point size.
For example, if you want a font that is Arial, bold, and
a point size of 18, you would call this method with:
"Arial-BOLD-18".
The default size is 12 and the default style is PLAIN.
If you don't specify a valid size, the returned
Font has a size of 12. If you don't specify
a valid style, the returned Font has a style of PLAIN.
If you do not provide a valid font family name in
the str argument, this method still returns
a valid font with a family name of "dialog".
To determine what font family names are available on
your system, use the
getAvailableFontFamilyNames() method.
If str is null, a new Font
is returned with the family name "dialog", a size of 12 and a
PLAIN style.
If str is null,
a new Font is returned with the name "dialog", a
size of 12 and a PLAIN style.
getFont
public static Font getFont(
Mapattributes
)
Returns a Font object from the system properties list.
getFont
public static Font getFont(
Stringnm,
Fontfont
)
Gets the specified Font from the system properties
list. As in the getProperty method of
System, the first
argument is treated as the name of a system property to be
obtained. The String value of this property is then
interpreted as a Font object.
The property value should be one of the following forms:
fontname-style-pointsize
fontname-pointsize
fontname-style
fontname
where style is one of the three case-insensitive strings
"BOLD", "BOLDITALIC", or
"ITALIC", and point size is a decimal
representation of the point size.
The default style is PLAIN. The default point size
is 12.
If the specified property is not found, the font
argument is returned instead.
Instance Methods
canDisplay
public boolean canDisplay(
char c
)
Checks if this Font has a glyph for the specified
character.
canDisplayUpTo
public int canDisplayUpTo(
char[] text,
int start,
int limit
)
Indicates whether or not this Font can display
the characters in the specified text
starting at start and ending at
limit. This method is a convenience overload.
canDisplayUpTo
public int canDisplayUpTo(
CharacterIteratoriter,
int start,
int limit
)
Indicates whether or not this Font can display
the specified String. For strings with Unicode
encoding, it is important to know if a particular font can display
the string. This method returns an offset
into the Stringstr which is the first
character this Font cannot display without using the
missing glyph code . If this Font can display all
characters, -1 is returned.
canDisplayUpTo
public int canDisplayUpTo(
Stringstr
)
Indicates whether or not this Font can display a
specified String. For strings with Unicode encoding,
it is important to know if a particular font can display the
string. This method returns an offset into the Stringstr which is the first character this
Font cannot display without using the missing glyph
code. If the Font can display all characters, -1 is
returned.
Creates a GlyphVector by
mapping characters to glyphs one-to-one based on the
Unicode cmap in this Font. This method does no other
processing besides the mapping of glyphs to characters. This
means that this method is not useful for some scripts, such
as Arabic, Hebrew, Thai, and Indic, that require reordering,
shaping, or ligature substitution.
Creates a GlyphVector by
mapping the specified characters to glyphs one-to-one based on the
Unicode cmap in this Font. This method does no other
processing besides the mapping of glyphs to characters. This
means that this method is not useful for some scripts, such
as Arabic, Hebrew, Thai, and Indic, that require reordering,
shaping, or ligature substitution.
Creates a GlyphVector by
mapping characters to glyphs one-to-one based on the
Unicode cmap in this Font. This method does no other
processing besides the mapping of glyphs to characters. This
means that this method is not useful for some scripts, such
as Arabic, Hebrew, Thai, and Indic, that require reordering,
shaping, or ligature substitution.
Creates a GlyphVector by
mapping characters to glyphs one-to-one based on the
Unicode cmap in this Font. This method does no other
processing besides the mapping of glyphs to characters. This
means that this method is not useful for some scripts, such
as Arabic, Hebrew, Thai, and Indic, that require reordering,
shaping, or ligature substitution.
Returns the keys of all the attributes supported by this
Font. These attributes can be used to derive other
fonts.
getBaselineFor
public byte getBaselineFor(
char c
)
Returns the baseline appropriate for displaying this character.
Large fonts can support different writing systems, and each system can
use a different baseline.
The character argument determines the writing system to use. Clients
should not assume all characters use the same baseline.
The family name of a font is font specific. Two fonts such as
Helvetica Italic and Helvetica Bold have the same family name,
Helvetica, whereas their font face names are
Helvetica Bold and Helvetica Italic. The list of
available family names may be obtained by using the
getAvailableFontFamilyNames() method.
Use getName to get the logical name of the font.
Use getFontName to get the font face name of the font.
Returns the family name of this Font, localized for
the specified locale.
The family name of a font is font specific. Two fonts such as
Helvetica Italic and Helvetica Bold have the same family name,
Helvetica, whereas their font face names are
Helvetica Bold and Helvetica Italic. The list of
available family names may be obtained by using the
getAvailableFontFamilyNames() method.
Use getFontName to get the font face name of the font.
Returns the font face name of this Font. For example,
Helvetica Bold could be returned as a font face name.
Use getFamily to get the family name of the font.
Use getName to get the logical name of the font.
Returns the font face name of the Font, localized
for the specified locale. For example, Helvetica Fett could be
returned as the font face name.
Use getFamily to get the family name of the font.
getItalicAngle
public float getItalicAngle(
)
Returns the italic angle of this Font. The italic angle
is the inverse slope of the caret which best matches the posture of this
Font.
getLineMetrics
public LineMetrics getLineMetrics(
char[] chars,
int beginIndex,
int limit,
FontRenderContextfrc
)
Returns a LineMetrics object created with the
specified arguments.
Returns the postscript name of this Font.
Use getFamily to get the family name of the font.
Use getFontName to get the font face name of the font.
getSize
public int getSize(
)
Returns the point size of this Font, rounded to
an integer.
Most users are familiar with the idea of using point size to
specify the size of glyphs in a font. This point size defines a
measurement between the baseline of one line to the baseline of the
following line in a single spaced text document. The point size is
based on typographic points, approximately 1/72 of an inch.
The Java(tm)2D API adopts the convention that one point is
equivalent to one unit in user coordinates. When using a
normalized transform for converting user space coordinates to
device space coordinates 72 user
space units equal 1 inch in device space. In this case one point
is 1/72 of an inch.
getSize2D
public float getSize2D(
)
Returns the point size of this Font in
float value.
getStringBounds
public Rectangle2D getStringBounds(
char[] chars,
int beginIndex,
int limit,
FontRenderContextfrc
)
Returns the logical bounds of the specified array of characters
in the specified FontRenderContext. The logical
bounds contains the origin, ascent, advance, and height, which
includes the leading. The logical bounds does not always enclose
all the text. For example, in some languages and in some fonts,
accent marks can be positioned above the ascent or below the
descent. To obtain a visual bounding box, which encloses all the
text, use the getBounds method of
TextLayout.
Returns the logical bounds of the characters indexed in the
specified CharacterIterator in the
specified FontRenderContext. The logical bounds
contains the origin, ascent, advance, and height, which includes
the leading. The logical bounds does not always enclose all the
text. For example, in some languages and in some fonts, accent
marks can be positioned above the ascent or below the descent.
To obtain a visual bounding box, which encloses all the text,
use the getBounds method of
TextLayout.
Returns the logical bounds of the specified String in
the specified FontRenderContext. The logical bounds
contains the origin, ascent, advance, and height, which includes
the leading. The logical bounds does not always enclose all the
text. For example, in some languages and in some fonts, accent
marks can be positioned above the ascent or below the descent.
To obtain a visual bounding box, which encloses all the text,
use the getBounds method of
TextLayout.
Returns the logical bounds of the specified String in
the specified FontRenderContext. The logical bounds
contains the origin, ascent, advance, and height, which includes
the leading. The logical bounds does not always enclose all the
text. For example, in some languages and in some fonts, accent
marks can be positioned above the ascent or below the descent.
To obtain a visual bounding box, which encloses all the text,
use the getBounds method of
TextLayout.
getStyle
public int getStyle(
)
Returns the style of this Font. The style can be
PLAIN, BOLD, ITALIC, or BOLD+ITALIC.
Returns a copy of the transform associated with this
Font.
hashCode
public int hashCode(
)
Returns a hashcode for this Font.
hasUniformLineMetrics
public boolean hasUniformLineMetrics(
)
Checks whether or not this Font has uniform
line metrics. A logical Font might be a
composite font, which means that it is composed of different
physical fonts to cover different code ranges. Each of these
fonts might have different LineMetrics. If the
logical Font is a single
font then the metrics would be uniform.
isBold
public boolean isBold(
)
Indicates whether or not this Font object's style is
BOLD.
isItalic
public boolean isItalic(
)
Indicates whether or not this Font object's style is
ITALIC.
isPlain
public boolean isPlain(
)
Indicates whether or not this Font object's style is
PLAIN.
isTransformed
public boolean isTransformed(
)
Indicates whether or not this Font object has a
transform that affects its size in addition to the Size
attribute.
layoutGlyphVector
public GlyphVector layoutGlyphVector(
FontRenderContextfrc,
char[] text,
int start,
int limit,
int flags
)
Returns a new GlyphVector object, performing full
layout of the text if possible. Full layout is required for
complex text, such as Arabic or Hindi. Support for different
scripts depends on the font and implementation.
Bidi, and should only be performed on text that
has a uniform direction. The direction is indicated in the
flags parameter,by using LAYOUT_RIGHT_TO_LEFT to indicate a
right-to-left (Arabic and Hebrew) run direction, or
LAYOUT_LEFT_TO_RIGHT to indicate a left-to-right (English)
run direction.
In addition, some operations, such as Arabic shaping, require
context, so that the characters at the start and limit can have
the proper shapes. Sometimes the data in the buffer outside
the provided range does not have valid data. The values
LAYOUT_NO_START_CONTEXT and LAYOUT_NO_LIMIT_CONTEXT can be
added to the flags parameter to indicate that the text before
start, or after limit, respectively, should not be examined
for context.
All other values for the flags parameter are reserved.