AI-generated Key Takeaways
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TextAttributedefines keys and values for customizing text rendering in Java applications, such as font, color, size, and style. -
Common attributes include
FONT,SIZE,WEIGHT,WIDTH,FOREGROUND,UNDERLINE, andSTRIKETHROUGH, which can be used to control various aspects of text appearance. -
Each attribute has predefined constants and supports a range of values for fine-grained control, and attribute values must be immutable, with out-of-range values reverting to defaults.
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TextAttributeinstances act as keys within aMapto specify desired text attributes for rendering. -
Developers can use
TextAttributeto achieve specific visual effects and improve text presentation in Java applications.
The TextAttribute class defines attribute keys and
attribute values used for text rendering.
TextAttribute instances are used as attribute keys to
identify attributes in classes handling text attributes. Other
constants defined in this class can be used as attribute values.
For each text attribute, the documentation provides:
- the type of its value,
- the relevant predefined constants, if any
- the default effect if the attribute is absent
- the valid values if there are limitations
- a description of the effect.
Values
- The values of attributes must always be immutable.
- Where value limitations are given, any value outside of that set is reserved for future use; the value will be treated as the default.
- The value
nullis treated the same as the default value and results in the default behavior. - If the value is not of the proper type, the attribute will be ignored.
- The identity of the value does not matter, only the actual
value. For example,
TextAttribute.WEIGHT_BOLDandnew Float(2.0)indicate the sameWEIGHT. - Attribute values of type
Number(used forWEIGHT,WIDTH,POSTURE,SIZE,JUSTIFICATION, andTRACKING) can vary along their natural range and are not restricted to the predefined constants.Number.floatValue()is used to get the actual value from theNumber. - The values for
WEIGHT,WIDTH, andPOSTUREare interpolated by the system, which can select the 'nearest available' font or use other techniques to approximate the user's request.
Field Summary
| public static final TextAttribute | BACKGROUND | Attribute key for the paint used to render the background of the text. |
| public static final TextAttribute | BIDI_EMBEDDING | Attribute key for the embedding level of the text. |
| public static final TextAttribute | CHAR_REPLACEMENT | Attribute key for a user-defined glyph to display in lieu of the font's standard glyph for a character. |
| public static final TextAttribute | FAMILY | Attribute key for the font name. |
| public static final TextAttribute | FONT | Attribute key used to provide the font to use to render text. |
| public static final TextAttribute | FOREGROUND | Attribute key for the paint used to render the text. |
| public static final TextAttribute | INPUT_METHOD_HIGHLIGHT | Attribute key for input method highlight styles. |
| public static final TextAttribute | INPUT_METHOD_UNDERLINE | Attribute key for input method underlines. |
| public static final TextAttribute | JUSTIFICATION | Attribute key for the justification of a paragraph. |
| public static final Float | JUSTIFICATION_FULL | Justify the line to the full requested width. |
| public static final Float | JUSTIFICATION_NONE | Do not allow the line to be justified. |
| public static final TextAttribute | KERNING | Attribute key to request kerning. |
| public static final Integer | KERNING_ON | Request standard kerning. |
| public static final TextAttribute | LIGATURES | Attribute key for enabling optional ligatures. |
| public static final Integer | LIGATURES_ON | Request standard optional ligatures. |
| public static final TextAttribute | NUMERIC_SHAPING | Attribute key for converting ASCII decimal digits to other decimal ranges. |
| public static final TextAttribute | POSTURE | Attribute key for the posture of a font. |
| public static final Float | POSTURE_OBLIQUE | The standard italic posture. |
| public static final Float | POSTURE_REGULAR | The standard posture, upright. |
| public static final TextAttribute | RUN_DIRECTION | Attribute key for the run direction of the line. |
| public static final Boolean | RUN_DIRECTION_LTR | Left-to-right run direction. |
| public static final Boolean | RUN_DIRECTION_RTL | Right-to-left run direction. |
| public static final TextAttribute | SIZE | Attribute key for the font size. |
| public static final TextAttribute | STRIKETHROUGH | Attribute key for strikethrough. |
| public static final Boolean | STRIKETHROUGH_ON | A single strikethrough. |
| public static final TextAttribute | SUPERSCRIPT | Attribute key for superscripting and subscripting. |
| public static final Integer | SUPERSCRIPT_SUB | Standard subscript. |
| public static final Integer | SUPERSCRIPT_SUPER | Standard superscript. |
| public static final TextAttribute | SWAP_COLORS | Attribute key for swapping foreground and background
Paints. |
| public static final Boolean | SWAP_COLORS_ON | Swap foreground and background. |
| public static final TextAttribute | TRACKING | Attribute key to control tracking. |
| public static final Float | TRACKING_LOOSE | Perform loose tracking. |
| public static final Float | TRACKING_TIGHT | Perform tight tracking. |
| public static final TextAttribute | TRANSFORM | Attribute key for the transform of a font. |
| public static final TextAttribute | UNDERLINE | Attribute key for underline. |
| public static final Integer | UNDERLINE_LOW_DASHED | Single pixel dashed low underline. |
| public static final Integer | UNDERLINE_LOW_DOTTED | Single pixel dotted low underline. |
| public static final Integer | UNDERLINE_LOW_GRAY | Double pixel gray low underline. |
| public static final Integer | UNDERLINE_LOW_ONE_PIXEL | Single pixel solid low underline. |
| public static final Integer | UNDERLINE_LOW_TWO_PIXEL | Double pixel solid low underline. |
| public static final Integer | UNDERLINE_ON | Standard underline. |
| public static final TextAttribute | WEIGHT | Attribute key for the weight of a font. |
| public static final Float | WEIGHT_BOLD | The standard bold weight. |
| public static final Float | WEIGHT_DEMIBOLD | A moderately lighter weight than WEIGHT_BOLD. |
| public static final Float | WEIGHT_DEMILIGHT | An intermediate weight between WEIGHT_LIGHT and
WEIGHT_STANDARD. |
| public static final Float | WEIGHT_EXTRABOLD | An extra heavy weight. |
| public static final Float | WEIGHT_EXTRA_LIGHT | The lightest predefined weight. |
| public static final Float | WEIGHT_HEAVY | A moderately heavier weight than WEIGHT_BOLD. |
| public static final Float | WEIGHT_LIGHT | The standard light weight. |
| public static final Float | WEIGHT_MEDIUM | An intermediate weight between WEIGHT_REGULAR and
WEIGHT_BOLD. |
| public static final Float | WEIGHT_REGULAR | The standard weight. |
| public static final Float | WEIGHT_SEMIBOLD | A moderately heavier weight than WEIGHT_REGULAR. |
| public static final Float | WEIGHT_ULTRABOLD | The heaviest predefined weight. |
| public static final TextAttribute | WIDTH | Attribute key for the width of a font. |
| public static final Float | WIDTH_CONDENSED | The most condensed predefined width. |
| public static final Float | WIDTH_EXTENDED | The most extended predefined width. |
| public static final Float | WIDTH_REGULAR | The standard width. |
| public static final Float | WIDTH_SEMI_CONDENSED | A moderately condensed width. |
| public static final Float | WIDTH_SEMI_EXTENDED | A moderately extended width. |
Inherited Field Summary
Protected Constructor Summary
Protected Method Summary
| Object |
readResolve()
Resolves instances being deserialized to the predefined constants.
|
Inherited Method Summary
Fields
public static final TextAttribute BACKGROUND
Attribute key for the paint used to render the background of
the text. Values are instances of Paint.
The default value is null, indicating that the background
should not be rendered.
The logical bounds of the text will be filled using this
Paint, and then the text will be rendered on top
of it (but see SWAP_COLORS).
The visual bounds of the text is extended to include the logical bounds, if necessary. The outline is not affected.
See Also
public static final TextAttribute BIDI_EMBEDDING
Attribute key for the embedding level of the text. Values are
instances of Integer. The default value is
null, indicating that the the Bidirectional
algorithm should run without explicit embeddings.
Positive values 1 through 61 are embedding levels,
negative values -1 through -61 are override levels.
The value 0 means that the base line direction is used. These
levels are passed in the embedding levels array to the Bidi constructor.
Note: When this attribute is present anywhere in a paragraph, then any Unicode bidi control characters (RLO, LRO, RLE, LRE, and PDF) in the paragraph are disregarded, and runs of text where this attribute is not present are treated as though it were present and had the value 0.
See Also
public static final TextAttribute CHAR_REPLACEMENT
Attribute key for a user-defined glyph to display in lieu of the font's standard glyph for a character. Values are intances of GraphicAttribute. The default value is null, indicating that the standard glyphs provided by the font should be used.
This attribute is used to reserve space for a graphic or
other component embedded in a line of text. It is required for
correct positioning of 'inline' components within a line when
bidirectional reordering (see Bidi) is
performed. Each character (Unicode code point) will be
rendered using the provided GraphicAttribute. Typically, the
characters to which this attribute is applied should be
\uFFFC.
The GraphicAttribute determines the logical and visual bounds of the text; the actual Font values are ignored.
public static final TextAttribute FAMILY
Attribute key for the font name. Values are instances of
String. The default value is
"Default", which causes the platform default font
family to be used.
The Font class defines constants for the logical
font names.
This defines the value passed as name to the
Font constructor. Both logical and physical
font names are allowed. If a font with the requested name
is not found, the default font is used.
Note: This attribute is unfortunately misnamed, as it specifies the face name and not just the family. Thus values such as "Lucida Sans Bold" will select that face if it exists. Note, though, that if the requested face does not exist, the default will be used with regular weight. The "Bold" in the name is part of the face name, not a separate request that the font's weight be bold.
public static final TextAttribute FONT
Attribute key used to provide the font to use to render text.
The default
value is null, indicating that normal resolution of a
Font from attributes should be performed.
TextLayout and
AttributedCharacterIterator work in terms of
Maps of TextAttributes. Normally,
all the attributes are examined and used to select and
configure a Font instance. If a FONT
attribute is present, though, its associated Font
will be used. This provides a way for users to override the
resolution of font attributes into a Font, or
force use of a particular Font instance. This
also allows users to specify subclasses of Font in
cases where a Font can be subclassed.
FONT is used for special situations where
clients already have a Font instance but still
need to use Map-based APIs. Typically, there will
be no other attributes in the Map except the
FONT attribute. With Map-based APIs
the common case is to specify all attributes individually, so
FONT is not needed or desireable.
However, if both FONT and other attributes are
present in the Map, the rendering system will
merge the attributes defined in the Font with the
additional attributes. This merging process classifies
TextAttributes into two groups. One group, the
'primary' group, is considered fundamental to the selection and
metric behavior of a font. These attributes are
FAMILY, WEIGHT, WIDTH,
POSTURE, SIZE,
TRANSFORM, SUPERSCRIPT, and
TRACKING. The other group, the 'secondary' group,
consists of all other defined attributes, with the exception of
FONT itself.
To generate the new Map, first the
Font is obtained from the FONT
attribute, and all of its attributes extracted into a
new Map. Then only the secondary
attributes from the original Map are added to
those in the new Map. Thus the values of primary
attributes come solely from the Font, and the
values of secondary attributes originate with the
Font but can be overridden by other values in the
Map.
public static final TextAttribute FOREGROUND
Attribute key for the paint used to render the text. Values are
instances of Paint. The default value is
null, indicating that the Paint set on the
Graphics2D at the time of rendering is used.
Glyphs will be rendered using this
Paint regardless of the Paint value
set on the Graphics (but see SWAP_COLORS).
See Also
public static final TextAttribute INPUT_METHOD_HIGHLIGHT
Attribute key for input method highlight styles.
The default value is null,
which means that input method styles should not be applied
before rendering.
See Also
public static final TextAttribute INPUT_METHOD_UNDERLINE
Attribute key for input method underlines. Values
are instances of Integer. The default
value is -1, which means no underline.
Several constant values are provided, see UNDERLINE_LOW_ONE_PIXEL, UNDERLINE_LOW_TWO_PIXEL,
UNDERLINE_LOW_DOTTED, UNDERLINE_LOW_GRAY, and
UNDERLINE_LOW_DASHED.
This may be used in conjunction with UNDERLINE if
desired. The primary purpose is for use by input methods.
Other use of these underlines for simple ornamentation might
confuse users.
The input method underline affects both the visual bounds and the outline of the text.
public static final TextAttribute JUSTIFICATION
Attribute key for the justification of a paragraph. Values are
instances of Number. The default value is
1, indicating that justification should use the full width
provided. Values are pinned to the range [0..1].
The constants JUSTIFICATION_FULL and JUSTIFICATION_NONE are provided.
Specifies the fraction of the extra space to use when
justification is requested on a TextLayout. For
example, if the line is 50 points wide and it is requested to
justify to 70 points, a value of 0.75 will pad to use
three-quarters of the remaining space, or 15 points, so that
the resulting line will be 65 points in length.
Note: This should have the same value for all the text in a paragraph, otherwise the behavior is undetermined.
public static final Float JUSTIFICATION_FULL
Justify the line to the full requested width. This is the
default value for JUSTIFICATION.
See Also
public static final TextAttribute KERNING
Attribute key to request kerning. Values are instances of
Integer. The default value is
0, which does not request kerning.
The constant value KERNING_ON is provided.
The default advances of single characters are not appropriate for some character sequences, for example "To" or "AWAY". Without kerning the adjacent characters appear to be separated by too much space. Kerning causes selected sequences of characters to be spaced differently for a more pleasing visual appearance.
public static final TextAttribute LIGATURES
Attribute key for enabling optional ligatures. Values are
instances of Integer. The default value is
0, which means do not use optional ligatures.
The constant value LIGATURES_ON is defined.
Ligatures required by the writing system are always enabled.
public static final TextAttribute NUMERIC_SHAPING
Attribute key for converting ASCII decimal digits to other
decimal ranges. Values are instances of NumericShaper.
The default is null, which means do not perform
numeric shaping.
When a numeric shaper is defined, the text is first processed by the shaper before any other analysis of the text is performed.
Note: This should have the same value for all the text in the paragraph, otherwise the behavior is undetermined.
See Also
public static final TextAttribute POSTURE
Attribute key for the posture of a font. Values are instances
of Number. The default value is
POSTURE_REGULAR.
Two constant values are provided, POSTURE_REGULAR
and POSTURE_OBLIQUE. The value
POSTURE_OBLIQUE corresponds to the style value
Font.ITALIC as passed to the Font
constructor.
The value is roughly the slope of the stems of the font, expressed as the run over the rise. Positive values lean right.
The system can interpolate the provided value.
This will affect the font's italic angle as returned by
Font.getItalicAngle.
public static final Float POSTURE_REGULAR
The standard posture, upright. This is the default value for
POSTURE.
See Also
public static final TextAttribute RUN_DIRECTION
Attribute key for the run direction of the line. Values are
instances of Boolean. The default value is
null, which indicates that the standard Bidi algorithm for
determining run direction should be used with the value Bidi.DIRECTION_DEFAULT_LEFT_TO_RIGHT.
The constants RUN_DIRECTION_RTL and RUN_DIRECTION_LTR are provided.
This determines the value passed to the Bidi constructor to select the primary direction of
the text in the paragraph.
Note: This attribute should have the same value for all the text in a paragraph, otherwise the behavior is undetermined.
See Also
public static final TextAttribute SIZE
Attribute key for the font size. Values are instances of
Number. The default value is 12pt.
This corresponds to the size parameter to the
Font constructor.
Very large or small sizes will impact rendering performance, and the rendering system might not render text at these sizes. Negative sizes are illegal and result in the default size.
Note that the appearance and metrics of a 12pt font with a 2x transform might be different than that of a 24 point font with no transform.
public static final TextAttribute STRIKETHROUGH
Attribute key for strikethrough. Values are instances of
Boolean. The default value is
false, which means no strikethrough.
The constant value STRIKETHROUGH_ON is provided.
The strikethrough affects both the visual bounds and the outline of the text.
public static final TextAttribute SUPERSCRIPT
Attribute key for superscripting and subscripting. Values are
instances of Integer. The default value is
0, which means that no superscript or subscript is used.
Two constant values are provided, see SUPERSCRIPT_SUPER and SUPERSCRIPT_SUB. These have
the values 1 and -1 respectively. Values of
greater magnitude define greater levels of superscript or
subscripting, for example, 2 corresponds to super-superscript,
3 to super-super-superscript, and similarly for negative values
and subscript, up to a level of 7 (or -7). Values beyond this
range are reserved; behavior is platform-dependent.
SUPERSCRIPT can
impact the ascent and descent of a font. The ascent
and descent can never become negative, however.
public static final TextAttribute SWAP_COLORS
Attribute key for swapping foreground and background
Paints. Values are instances of
Boolean. The default value is
false, which means do not swap colors.
The constant value SWAP_COLORS_ON is defined.
If the FOREGROUND attribute is set, its
Paint will be used as the background, otherwise
the Paint currently on the Graphics
will be used. If the BACKGROUND attribute is set, its
Paint will be used as the foreground, otherwise
the system will find a contrasting color to the
(resolved) background so that the text will be visible.
See Also
public static final TextAttribute TRACKING
Attribute key to control tracking. Values are instances of
Number. The default value is
0, which means no additional tracking.
The constant values TRACKING_TIGHT and TRACKING_LOOSE are provided.
The tracking value is multiplied by the font point size and
passed through the font transform to determine an additional
amount to add to the advance of each glyph cluster. Positive
tracking values will inhibit formation of optional ligatures.
Tracking values are typically between -0.1 and
0.3; values outside this range are generally not
desireable.
public static final TextAttribute TRANSFORM
Attribute key for the transform of a font. Values are
instances of TransformAttribute. The
default value is TransformAttribute.IDENTITY.
The primary intent is to support scaling and skewing, though other effects are possible.
Some transforms will cause the baseline to be rotated and/or shifted. The text and the baseline are transformed together so that the text follows the new baseline. For example, with text on a horizontal baseline, the new baseline follows the direction of the unit x vector passed through the transform. Text metrics are measured against this new baseline. So, for example, with other things being equal, text rendered with a rotated TRANSFORM and an unrotated TRANSFORM will measure as having the same ascent, descent, and advance.
public static final TextAttribute UNDERLINE
Attribute key for underline. Values are instances of
Integer. The default value is -1, which
means no underline.
The constant value UNDERLINE_ON is provided.
The underline affects both the visual bounds and the outline of the text.
public static final TextAttribute WEIGHT
Attribute key for the weight of a font. Values are instances
of Number. The default value is
WEIGHT_REGULAR.
Several constant values are provided, see WEIGHT_EXTRA_LIGHT, WEIGHT_LIGHT, WEIGHT_DEMILIGHT, WEIGHT_REGULAR, WEIGHT_SEMIBOLD, WEIGHT_MEDIUM, WEIGHT_DEMIBOLD, WEIGHT_BOLD, WEIGHT_HEAVY,
WEIGHT_EXTRABOLD, and WEIGHT_ULTRABOLD. The
value WEIGHT_BOLD corresponds to the
style value Font.BOLD as passed to the
Font constructor.
The value is roughly the ratio of the stem width to that of the regular weight.
The system can interpolate the provided value.
public static final Float WEIGHT_DEMILIGHT
An intermediate weight between WEIGHT_LIGHT and
WEIGHT_STANDARD.
See Also
public static final Float WEIGHT_MEDIUM
An intermediate weight between WEIGHT_REGULAR and
WEIGHT_BOLD.
See Also
public static final Float WEIGHT_REGULAR
The standard weight. This is the default value for WEIGHT.
See Also
public static final TextAttribute WIDTH
Attribute key for the width of a font. Values are instances of
Number. The default value is
WIDTH_REGULAR.
Several constant values are provided, see WIDTH_CONDENSED, WIDTH_SEMI_CONDENSED, WIDTH_REGULAR, WIDTH_SEMI_EXTENDED, WIDTH_EXTENDED.
The value is roughly the ratio of the advance width to that of the regular width.
The system can interpolate the provided value.
public static final Float WIDTH_REGULAR
The standard width. This is the default value for
WIDTH.
See Also
Protected Constructors
protected TextAttribute (String name)
Constructs a TextAttribute with the specified name.
Parameters
| name | the attribute name to assign to this
TextAttribute
|
|---|
Protected Methods
protected Object readResolve ()
Resolves instances being deserialized to the predefined constants.
Returns
- the resolved
Attributeobject
Throws
| InvalidObjectException |
|---|