Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class GlyphMetrics - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.awt.font
Class GlyphMetrics

java.lang.Object
  |
  +--java.awt.font.GlyphMetrics

public final class GlyphMetrics
extends Object

The GlyphMetrics class represents infomation for a single glyph. A glyph is the visual representation of one or more characters. Many different glyphs can be used to represent a single character or combination of characters. GlyphMetrics instances are produced by Font and are applicable to a specific glyph in a particular Font.

Glyphs are either STANDARD, LIGATURE, COMBINING, or COMPONENT.

STANDARD glyphs are commonly used to represent single characters.
LIGATURE glyphs are used to represent sequences of characters.
COMPONENT glyphs in a GlyphVector do not correspond to a particular character in a text model. Instead, COMPONENT glyphs are added for typographical reasons, such as Arabic justification.
COMBINING glyphs embellish STANDARD or LIGATURE glyphs, such as accent marks. Carets do not appear before COMBINING glyphs.

Other metrics available through GlyphMetrics are the advance, bounds, and left and right side bearings.

The advance of a glyph is the distance from the glyph's origin to the origin of the next glyph. Note that, in a GlyphVector, the distance from a glyph to its following glyph might not be the glyph's advance.

The bounds is the smallest rectangle that completely contains the visible portion of the glyph. The bounds rectangle is relative to the glyph's origin. The left-side bearing is the distance from the glyph origin to the left of its bounds rectangle. If the left-side bearing is negative, part of the glyph is drawn to the left of its origin. The right-side bearing is the distance from the right side of the bounds rectangle to the next glyph origin (the origin plus the advance). If negative, part of the glyph is drawn to the right of the next glyph's origin.

Although instances of GlyphMetrics can be directly constructed, they are almost always obtained from a GlyphVector. Once constructed, GlyphMetrics objects are immutable.

Example:

Querying a Font for glyph information

 Font font = ...;
 int glyphIndex = ...;
 GlyphMetrics metrics = GlyphVector.getGlyphMetrics(glyphIndex);
 int isStandard = metrics.isStandard();
 float glyphAdvance = metrics.getAdvance();

See Also:: Font, GlyphVector

Field Summary

static byte COMBINING
          Indicates a glyph that represents a combining character, such as an umlaut.

static byte COMPONENT
          Indicates a glyph with no corresponding character in the backing store.

static byte LIGATURE
          Indicates a glyph that represents multiple characters as a ligature, for example 'fi' or 'ffi'.

static byte STANDARD
          Indicates a glyph that represents a single standard character.

static byte WHITESPACE
          Indicates a glyph with no visual representation.

Constructor Summary

GlyphMetrics(float advance, Rectangle2D bounds, byte glyphType)
          Constructs a GlyphMetrics object.

Method Summary

float getAdvance()
          Returns the advance width or height of the glyph.

Rectangle2D getBounds2D()
          Returns the black box bounds of the glyph.

float getLSB()
          Returns the left (top) side bearing of the glyph.

float getRSB()
          Returns the right (bottom) side bearing of the glyph.

int getType()
          Returns the raw glyph type code.

boolean isCombining()
          Returns true if this is a combining glyph.

boolean isComponent()
          Returns true if this is a component glyph.

boolean isLigature()
          Returns true if this is a ligature glyph.

boolean isStandard()
          Returns true if this is a standard glyph.

boolean isWhitespace()
          Returns true if this is a whitespace glyph.

Methods inherited from class java.lang.Object

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

Field Detail

STANDARD

public static final byte STANDARD

Indicates a glyph that represents a single standard character.

LIGATURE

public static final byte LIGATURE

Indicates a glyph that represents multiple characters as a ligature, for example 'fi' or 'ffi'. It is followed by filler glyphs for the remaining characters. Filler and combining glyphs can be intermixed to control positioning of accent marks on the logically preceeding ligature.

COMBINING

public static final byte COMBINING

Indicates a glyph that represents a combining character, such as an umlaut. There is no caret position between this glyph and the preceeding glyph.

COMPONENT

public static final byte COMPONENT

Indicates a glyph with no corresponding character in the backing store. The glyph is associated with the character represented by the logicaly preceeding non-component glyph. This is used for kashida justification or other visual modifications to existing glyphs. There is no caret position between this glyph and the preceeding glyph.

WHITESPACE

public static final byte WHITESPACE

Indicates a glyph with no visual representation. It can be added to the other code values to indicate an invisible glyph.

Constructor Detail

GlyphMetrics

public GlyphMetrics(float advance,
                    Rectangle2D bounds,
                    byte glyphType)

Constructs a GlyphMetrics object.

Parameters:: advance - the advance width or height of the glyph; bounds - the black box bounds of the glyph; glyphType - the type of the glyph

Method Detail

getAdvance

public float getAdvance()

Returns the advance width or height of the glyph.

Returns:: the advance of the glyph.

getBounds2D

public Rectangle2D getBounds2D()

Returns the black box bounds of the glyph.

Returns:: a Rectangle2D that is the bounds of the glyph.

getLSB

public float getLSB()

Returns the left (top) side bearing of the glyph.

This is the distance from 0, 0 to the left (top) of the glyph bounds. If the bounds of the glyph is to the left of (above) the origin, the LSB is negative.

Returns:: the left side bearing of the glyph.

getRSB

public float getRSB()

Returns the right (bottom) side bearing of the glyph.

This is the distance from the right (bottom) of the glyph bounds to the advance. If the bounds of the glyph is to the right of (below) the advance, the RSB is negative.

Returns:: the right side bearing of the glyph.

getType

public int getType()

Returns the raw glyph type code.

Returns:: the raw glyph type code.

isStandard

public boolean isStandard()

Returns true if this is a standard glyph.

Returns:: true if this is a standard glyph; false otherwise.

isLigature

public boolean isLigature()

Returns true if this is a ligature glyph.

Returns:: true if this is a ligature glyph; false otherwise.

isCombining

public boolean isCombining()

Returns true if this is a combining glyph.

Returns:: true if this is a combining glyph; false otherwise.

isComponent

public boolean isComponent()

Returns true if this is a component glyph.

Returns:: true if this is a component glyph; false otherwise.

isWhitespace

public boolean isWhitespace()

Returns true if this is a whitespace glyph.

Returns:: true if this is a whitespace glyph; false otherwise.