java.awt.font

## Class TextAttribute

- java.lang.Object
- - java.text.AttributedCharacterIterator.Attribute
  - - java.awt.font.TextAttribute

- All Implemented Interfaces:
    Serializable

      public final class TextAttribute
      extends AttributedCharacterIterator.Attribute

  The `TextAttribute` class defines attribute keys and attribute values used for text rendering.

  `TextAttribute` instances are used as attribute keys to identify attributes in `Font`, `TextLayout`, `AttributedCharacterIterator`, and other 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 `null` is 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_BOLD` and `new Float(2.0)` indicate the same `WEIGHT`.
  - Attribute values of type `Number` (used for `WEIGHT`, `WIDTH`, `POSTURE`, `SIZE`, `JUSTIFICATION`, and `TRACKING`) can vary along their natural range and are not restricted to the predefined constants. `Number.floatValue()` is used to get the actual value from the `Number`.
  - The values for `WEIGHT`, `WIDTH`, and `POSTURE` are interpolated by the system, which can select the 'nearest available' font or use other techniques to approximate the user's request.

  #### Summary of attributes

  Key | Value Type | Principal Constants | Default Value
  --- | --- | --- | ---
  `FAMILY` | String | See Font `DIALOG`, `DIALOG_INPUT`, `SERIF`, `SANS_SERIF`, and `MONOSPACED`. | "Default" (use platform default)
  `WEIGHT` | Number | WEIGHT_REGULAR, WEIGHT_BOLD | WEIGHT_REGULAR
  `WIDTH` | Number | WIDTH_CONDENSED, WIDTH_REGULAR, WIDTH_EXTENDED | WIDTH_REGULAR
  `POSTURE` | Number | POSTURE_REGULAR, POSTURE_OBLIQUE | POSTURE_REGULAR
  `SIZE` | Number | none | 12.0
  `TRANSFORM` | `TransformAttribute` | See TransformAttribute `IDENTITY` | TransformAttribute.IDENTITY
  `SUPERSCRIPT` | Integer | SUPERSCRIPT_SUPER, SUPERSCRIPT_SUB | 0 (use the standard glyphs and metrics)
  `FONT` | `Font` | none | null (do not override font resolution)
  `CHAR_REPLACEMENT` | `GraphicAttribute` | none | null (draw text using font glyphs)
  `FOREGROUND` | `Paint` | none | null (use current graphics paint)
  `BACKGROUND` | `Paint` | none | null (do not render background)
  `UNDERLINE` | Integer | UNDERLINE_ON | -1 (do not render underline)
  `STRIKETHROUGH` | Boolean | STRIKETHROUGH_ON | false (do not render strikethrough)
  `RUN_DIRECTION` | Boolean | RUN_DIRECTION_LTR RUN_DIRECTION_RTL | null (use `Bidi` standard default)
  `BIDI_EMBEDDING` | Integer | none | 0 (use base line direction)
  `JUSTIFICATION` | Number | JUSTIFICATION_FULL | JUSTIFICATION_FULL
  `INPUT_METHOD_HIGHLIGHT` | `InputMethodHighlight`, `Annotation` | (see class) | null (do not apply input highlighting)
  `INPUT_METHOD_UNDERLINE` | Integer | UNDERLINE_LOW_ONE_PIXEL, UNDERLINE_LOW_TWO_PIXEL | -1 (do not render underline)
  `SWAP_COLORS` | Boolean | SWAP_COLORS_ON | false (do not swap colors)
  `NUMERIC_SHAPING` | `NumericShaper` | none | null (do not shape digits)
  `KERNING` | Integer | KERNING_ON | 0 (do not request kerning)
  `LIGATURES` | Integer | LIGATURES_ON | 0 (do not form optional ligatures)
  `TRACKING` | Number | TRACKING_LOOSE, TRACKING_TIGHT | 0 (do not add tracking)

  See Also:
    `Font`, `TextLayout`, `AttributedCharacterIterator`, Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static TextAttribute` | `BACKGROUND` Attribute key for the paint used to render the background of the text.
    `static TextAttribute` | `BIDI_EMBEDDING` Attribute key for the embedding level of the text.
    `static TextAttribute` | `CHAR_REPLACEMENT` Attribute key for a user-defined glyph to display in lieu of the font's standard glyph for a character.
    `static TextAttribute` | `FAMILY` Attribute key for the font name.
    `static TextAttribute` | `FONT` Attribute key used to provide the font to use to render text.
    `static TextAttribute` | `FOREGROUND` Attribute key for the paint used to render the text.
    `static TextAttribute` | `INPUT_METHOD_HIGHLIGHT` Attribute key for input method highlight styles.
    `static TextAttribute` | `INPUT_METHOD_UNDERLINE` Attribute key for input method underlines.
    `static TextAttribute` | `JUSTIFICATION` Attribute key for the justification of a paragraph.
    `static Float` | `JUSTIFICATION_FULL` Justify the line to the full requested width.
    `static Float` | `JUSTIFICATION_NONE` Do not allow the line to be justified.
    `static TextAttribute` | `KERNING` Attribute key to request kerning.
    `static Integer` | `KERNING_ON` Request standard kerning.
    `static TextAttribute` | `LIGATURES` Attribute key for enabling optional ligatures.
    `static Integer` | `LIGATURES_ON` Request standard optional ligatures.
    `static TextAttribute` | `NUMERIC_SHAPING` Attribute key for converting ASCII decimal digits to other decimal ranges.
    `static TextAttribute` | `POSTURE` Attribute key for the posture of a font.
    `static Float` | `POSTURE_OBLIQUE` The standard italic posture.
    `static Float` | `POSTURE_REGULAR` The standard posture, upright.
    `static TextAttribute` | `RUN_DIRECTION` Attribute key for the run direction of the line.
    `static Boolean` | `RUN_DIRECTION_LTR` Left-to-right run direction.
    `static Boolean` | `RUN_DIRECTION_RTL` Right-to-left run direction.
    `static TextAttribute` | `SIZE` Attribute key for the font size.
    `static TextAttribute` | `STRIKETHROUGH` Attribute key for strikethrough.
    `static Boolean` | `STRIKETHROUGH_ON` A single strikethrough.
    `static TextAttribute` | `SUPERSCRIPT` Attribute key for superscripting and subscripting.
    `static Integer` | `SUPERSCRIPT_SUB` Standard subscript.
    `static Integer` | `SUPERSCRIPT_SUPER` Standard superscript.
    `static TextAttribute` | `SWAP_COLORS` Attribute key for swapping foreground and background `Paints`.
    `static Boolean` | `SWAP_COLORS_ON` Swap foreground and background.
    `static TextAttribute` | `TRACKING` Attribute key to control tracking.
    `static Float` | `TRACKING_LOOSE` Perform loose tracking.
    `static Float` | `TRACKING_TIGHT` Perform tight tracking.
    `static TextAttribute` | `TRANSFORM` Attribute key for the transform of a font.
    `static TextAttribute` | `UNDERLINE` Attribute key for underline.
    `static Integer` | `UNDERLINE_LOW_DASHED` Single pixel dashed low underline.
    `static Integer` | `UNDERLINE_LOW_DOTTED` Single pixel dotted low underline.
    `static Integer` | `UNDERLINE_LOW_GRAY` Double pixel gray low underline.
    `static Integer` | `UNDERLINE_LOW_ONE_PIXEL` Single pixel solid low underline.
    `static Integer` | `UNDERLINE_LOW_TWO_PIXEL` Double pixel solid low underline.
    `static Integer` | `UNDERLINE_ON` Standard underline.
    `static TextAttribute` | `WEIGHT` Attribute key for the weight of a font.
    `static Float` | `WEIGHT_BOLD` The standard bold weight.
    `static Float` | `WEIGHT_DEMIBOLD` A moderately lighter weight than `WEIGHT_BOLD`.
    `static Float` | `WEIGHT_DEMILIGHT` An intermediate weight between `WEIGHT_LIGHT` and `WEIGHT_STANDARD`.
    `static Float` | `WEIGHT_EXTRA_LIGHT` The lightest predefined weight.
    `static Float` | `WEIGHT_EXTRABOLD` An extra heavy weight.
    `static Float` | `WEIGHT_HEAVY` A moderately heavier weight than `WEIGHT_BOLD`.
    `static Float` | `WEIGHT_LIGHT` The standard light weight.
    `static Float` | `WEIGHT_MEDIUM` An intermediate weight between `WEIGHT_REGULAR` and `WEIGHT_BOLD`.
    `static Float` | `WEIGHT_REGULAR` The standard weight.
    `static Float` | `WEIGHT_SEMIBOLD` A moderately heavier weight than `WEIGHT_REGULAR`.
    `static Float` | `WEIGHT_ULTRABOLD` The heaviest predefined weight.
    `static TextAttribute` | `WIDTH` Attribute key for the width of a font.
    `static Float` | `WIDTH_CONDENSED` The most condensed predefined width.
    `static Float` | `WIDTH_EXTENDED` The most extended predefined width.
    `static Float` | `WIDTH_REGULAR` The standard width.
    `static Float` | `WIDTH_SEMI_CONDENSED` A moderately condensed width.
    `static Float` | `WIDTH_SEMI_EXTENDED` A moderately extended width.

    - ### Fields inherited from class java.text.AttributedCharacterIterator.Attribute

      `INPUT_METHOD_SEGMENT, LANGUAGE, READING`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `TextAttribute(String name)` Constructs a `TextAttribute` with the specified name.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected Object` | `readResolve()` Resolves instances being deserialized to the predefined constants.

    - ### Methods inherited from class java.text.AttributedCharacterIterator.Attribute

      `equals, getName, hashCode, toString`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### FAMILY

          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 `DIALOG`, `DIALOG_INPUT`, `SANS_SERIF`, `SERIF`, and `MONOSPACED`.

      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.

    - #### WEIGHT

          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.

    - #### WEIGHT_EXTRA_LIGHT

          public static final Float WEIGHT_EXTRA_LIGHT

      The lightest predefined weight.
      See Also:
        `WEIGHT`

    - #### WEIGHT_LIGHT

          public static final Float WEIGHT_LIGHT

      The standard light weight.
      See Also:
        `WEIGHT`

    - #### WEIGHT_DEMILIGHT

          public static final Float WEIGHT_DEMILIGHT

      An intermediate weight between `WEIGHT_LIGHT` and `WEIGHT_STANDARD`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_REGULAR

          public static final Float WEIGHT_REGULAR

      The standard weight. This is the default value for `WEIGHT`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_SEMIBOLD

          public static final Float WEIGHT_SEMIBOLD

      A moderately heavier weight than `WEIGHT_REGULAR`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_MEDIUM

          public static final Float WEIGHT_MEDIUM

      An intermediate weight between `WEIGHT_REGULAR` and `WEIGHT_BOLD`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_DEMIBOLD

          public static final Float WEIGHT_DEMIBOLD

      A moderately lighter weight than `WEIGHT_BOLD`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_BOLD

          public static final Float WEIGHT_BOLD

      The standard bold weight.
      See Also:
        `WEIGHT`

    - #### WEIGHT_HEAVY

          public static final Float WEIGHT_HEAVY

      A moderately heavier weight than `WEIGHT_BOLD`.
      See Also:
        `WEIGHT`

    - #### WEIGHT_EXTRABOLD

          public static final Float WEIGHT_EXTRABOLD

      An extra heavy weight.
      See Also:
        `WEIGHT`

    - #### WEIGHT_ULTRABOLD

          public static final Float WEIGHT_ULTRABOLD

      The heaviest predefined weight.
      See Also:
        `WEIGHT`

    - #### WIDTH

          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.

    - #### WIDTH_CONDENSED

          public static final Float WIDTH_CONDENSED

      The most condensed predefined width.
      See Also:
        `WIDTH`

    - #### WIDTH_SEMI_CONDENSED

          public static final Float WIDTH_SEMI_CONDENSED

      A moderately condensed width.
      See Also:
        `WIDTH`

    - #### WIDTH_REGULAR

          public static final Float WIDTH_REGULAR

      The standard width. This is the default value for `WIDTH`.
      See Also:
        `WIDTH`

    - #### WIDTH_SEMI_EXTENDED

          public static final Float WIDTH_SEMI_EXTENDED

      A moderately extended width.
      See Also:
        `WIDTH`

    - #### WIDTH_EXTENDED

          public static final Float WIDTH_EXTENDED

      The most extended predefined width.
      See Also:
        `WIDTH`

    - #### POSTURE

          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`.

      See Also:
        `Font.getItalicAngle()`

    - #### POSTURE_REGULAR

          public static final Float POSTURE_REGULAR

      The standard posture, upright. This is the default value for `POSTURE`.
      See Also:
        `POSTURE`

    - #### POSTURE_OBLIQUE

          public static final Float POSTURE_OBLIQUE

      The standard italic posture.
      See Also:
        `POSTURE`

    - #### SIZE

          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.

    - #### TRANSFORM

          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 `TransformAttribute` class defines the constant `IDENTITY`.

      This corresponds to the transform passed to `Font.deriveFont(AffineTransform)`. Since that transform is mutable and `TextAttribute` values must not be, the `TransformAttribute` wrapper class is used.

      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.

      In styled text, the baselines for each such run are aligned one after the other to potentially create a non-linear baseline for the entire run of text. For more information, see `TextLayout.getLayoutPath()`.

      See Also:
        `TransformAttribute`, `AffineTransform`

    - #### SUPERSCRIPT

          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.

    - #### SUPERSCRIPT_SUPER

          public static final Integer SUPERSCRIPT_SUPER

      Standard superscript.
      See Also:
        `SUPERSCRIPT`

    - #### SUPERSCRIPT_SUB

          public static final Integer SUPERSCRIPT_SUB

      Standard subscript.
      See Also:
        `SUPERSCRIPT`

    - #### FONT

          public static final TextAttribute FONT

      Attribute key used to provide the font to use to render text. Values are instances of `Font`. 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`.

      Note:`Font's` `Map`-based constructor and `deriveFont` methods do not process the `FONT` attribute, as these are used to create new `Font` objects. Instead, `Font.getFont(Map)` should be used to handle the `FONT` attribute.

      See Also:
        `Font`

    - #### CHAR_REPLACEMENT

          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.

      See Also:
        `GraphicAttribute`

    - #### FOREGROUND

          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:
        `Paint`, `SWAP_COLORS`

    - #### BACKGROUND

          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:
        `Paint`, `SWAP_COLORS`

    - #### UNDERLINE

          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.

    - #### UNDERLINE_ON

          public static final Integer UNDERLINE_ON

      Standard underline.
      See Also:
        `UNDERLINE`

    - #### STRIKETHROUGH

          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.

    - #### STRIKETHROUGH_ON

          public static final Boolean STRIKETHROUGH_ON

      A single strikethrough.
      See Also:
        `STRIKETHROUGH`

    - #### RUN_DIRECTION

          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:
        `Bidi`

    - #### RUN_DIRECTION_LTR

          public static final Boolean RUN_DIRECTION_LTR

      Left-to-right run direction.
      See Also:
        `RUN_DIRECTION`

    - #### RUN_DIRECTION_RTL

          public static final Boolean RUN_DIRECTION_RTL

      Right-to-left run direction.
      See Also:
        `RUN_DIRECTION`

    - #### BIDI_EMBEDDING

          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:
        `Bidi`

    - #### JUSTIFICATION

          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.

      See Also:
        `TextLayout.getJustifiedLayout(float)`

    - #### JUSTIFICATION_FULL

          public static final Float JUSTIFICATION_FULL

      Justify the line to the full requested width. This is the default value for `JUSTIFICATION`.
      See Also:
        `JUSTIFICATION`

    - #### JUSTIFICATION_NONE

          public static final Float JUSTIFICATION_NONE

      Do not allow the line to be justified.
      See Also:
        `JUSTIFICATION`

    - #### INPUT_METHOD_HIGHLIGHT

          public static final TextAttribute INPUT_METHOD_HIGHLIGHT

      Attribute key for input method highlight styles.

      Values are instances of `InputMethodHighlight` or `Annotation`. The default value is `null`, which means that input method styles should not be applied before rendering.

      If adjacent runs of text with the same `InputMethodHighlight` need to be rendered separately, the `InputMethodHighlights` should be wrapped in `Annotation` instances.

      Input method highlights are used while text is being composed by an input method. Text editing components should retain them even if they generally only deal with unstyled text, and make them available to the drawing routines.

      See Also:
        `Font`, `InputMethodHighlight`, `Annotation`

    - #### INPUT_METHOD_UNDERLINE

          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.

      Since:
        1.3

    - #### UNDERLINE_LOW_ONE_PIXEL

          public static final Integer UNDERLINE_LOW_ONE_PIXEL

      Single pixel solid low underline.
      Since:
        1.3
      See Also:
        `INPUT_METHOD_UNDERLINE`

    - #### UNDERLINE_LOW_TWO_PIXEL

          public static final Integer UNDERLINE_LOW_TWO_PIXEL

      Double pixel solid low underline.
      Since:
        1.3
      See Also:
        `INPUT_METHOD_UNDERLINE`

    - #### UNDERLINE_LOW_DOTTED

          public static final Integer UNDERLINE_LOW_DOTTED

      Single pixel dotted low underline.
      Since:
        1.3
      See Also:
        `INPUT_METHOD_UNDERLINE`

    - #### UNDERLINE_LOW_GRAY

          public static final Integer UNDERLINE_LOW_GRAY

      Double pixel gray low underline.
      Since:
        1.3
      See Also:
        `INPUT_METHOD_UNDERLINE`

    - #### UNDERLINE_LOW_DASHED

          public static final Integer UNDERLINE_LOW_DASHED

      Single pixel dashed low underline.
      Since:
        1.3
      See Also:
        `INPUT_METHOD_UNDERLINE`

    - #### SWAP_COLORS

          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:
        `FOREGROUND`, `BACKGROUND`

    - #### SWAP_COLORS_ON

          public static final Boolean SWAP_COLORS_ON

      Swap foreground and background.
      Since:
        1.3
      See Also:
        `SWAP_COLORS`

    - #### NUMERIC_SHAPING

          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.

      Since:
        1.4
      See Also:
        `NumericShaper`

    - #### KERNING

          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.

      Since:
        1.6

    - #### KERNING_ON

          public static final Integer KERNING_ON

      Request standard kerning.
      Since:
        1.6
      See Also:
        `KERNING`

    - #### LIGATURES

          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.

      Since:
        1.6

    - #### LIGATURES_ON

          public static final Integer LIGATURES_ON

      Request standard optional ligatures.
      Since:
        1.6
      See Also:
        `LIGATURES`

    - #### TRACKING

          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.

      Since:
        1.6

    - #### TRACKING_TIGHT

          public static final Float TRACKING_TIGHT

      Perform tight tracking.
      Since:
        1.6
      See Also:
        `TRACKING`

    - #### TRACKING_LOOSE

          public static final Float TRACKING_LOOSE

      Perform loose tracking.
      Since:
        1.6
      See Also:
        `TRACKING`

  - ### Constructor Detail

    - #### TextAttribute

          protected TextAttribute(String name)

      Constructs a `TextAttribute` with the specified name.
      Parameters:
        `name` - the attribute name to assign to this `TextAttribute`

  - ### Method Detail

    - #### readResolve

          protected Object readResolve()
                                throws InvalidObjectException

      Resolves instances being deserialized to the predefined constants.
      Overrides:
        `readResolve` in class `AttributedCharacterIterator.Attribute`
      Returns:
        the resolved `Attribute` object
      Throws:
        `InvalidObjectException` - if the object to resolve is not an instance of `Attribute`

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