File Doc Category Size Date Package
GlyphMetrics.java API Doc Java SE 6 API 10660 Tue Jun 10 00:25:24 BST 2008 java.awt.font

GlyphMetrics

java.lang.Object

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 {@link java.awt.Font 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 {@link 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 components of the advance, the visual bounds, and the left and right side bearings.

Glyphs for a rotated font, or obtained from a GlyphVector which has applied a rotation to the glyph, can have advances that contain both X and Y components. Usually the advance only has one component.

The advance of a glyph is the distance from the glyph's origin to the origin of the next glyph along the baseline, which is either vertical or horizontal. Note that, in a GlyphVector, the distance from a glyph to its following glyph might not be the glyph's advance, because of kerning or other positioning adjustments.

The bounds is the smallest rectangle that completely contains the outline 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. Note that the bounds does not necessarily enclose all the pixels affected when rendering the glyph, because of rasterization and pixel adjustment effects.

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: java.awt.Font
see: GlyphVector

Fields Summary
private boolean
horizontal
Indicates whether the metrics are for a horizontal or vertical baseline.
private float
advanceX
The x-component of the advance.
private float
advanceY
The y-component of the advance.
private Rectangle2D$Float
bounds
The bounds of the associated glyph.
private byte
glyphType
Additional information about the glyph encoded as a byte.
public static final byte
STANDARD
Indicates a glyph that represents a single standard character.
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.
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.
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.
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.
Constructors Summary
public GlyphMetrics(float advance, Rectangle2D bounds, byte glyphType)
Constructs a GlyphMetrics object.
param
advance the advance width of the glyph
param
bounds the black box bounds of the glyph
param
glyphType the type of the glyph
this.horizontal = true; this.advanceX = advance; this.advanceY = 0; this.bounds = new Rectangle2D.Float(); this.bounds.setRect(bounds); this.glyphType = glyphType;
public GlyphMetrics(boolean horizontal, float advanceX, float advanceY, Rectangle2D bounds, byte glyphType)
Constructs a GlyphMetrics object.
param
horizontal if true, metrics are for a horizontal baseline, otherwise they are for a vertical baseline
param
advanceX the X-component of the glyph's advance
param
advanceY the Y-component of the glyph's advance
param
bounds the visual bounds of the glyph
param
glyphType the type of the glyph
since
1.4
this.horizontal = horizontal; this.advanceX = advanceX; this.advanceY = advanceY; this.bounds = new Rectangle2D.Float(); this.bounds.setRect(bounds); this.glyphType = glyphType;
Methods Summary
public float getAdvance()
Returns the advance of the glyph along the baseline (either horizontal or vertical).
return
the advance of the glyph
return horizontal ? advanceX : advanceY;
public float getAdvanceX()
Returns the x-component of the advance of the glyph.
return
the x-component of the advance of the glyph
since
1.4
return advanceX;
public float getAdvanceY()
Returns the y-component of the advance of the glyph.
return
the y-component of the advance of the glyph
since
1.4
return advanceY;
public java.awt.geom.Rectangle2D getBounds2D()
Returns the bounds of the glyph. This is the bounding box of the glyph outline. Because of rasterization and pixel alignment effects, it does not necessarily enclose the pixels that are affected when rendering the glyph.
return
a {@link Rectangle2D} that is the bounds of the glyph.
return new Rectangle2D.Float(bounds.x, bounds.y, bounds.width, bounds.height);
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.
return
the left side bearing of the glyph.
return horizontal ? bounds.x : bounds.y;
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.
return
the right side bearing of the glyph.
return horizontal ? advanceX - bounds.x - bounds.width : advanceY - bounds.y - bounds.height;
public int getType()
Returns the raw glyph type code.
return
the raw glyph type code.
return glyphType;
public boolean isCombining()
Returns true if this is a combining glyph.
return
true if this is a combining glyph; false otherwise.
return (glyphType & 0x3) == COMBINING;
public boolean isComponent()
Returns true if this is a component glyph.
return
true if this is a component glyph; false otherwise.
return (glyphType & 0x3) == COMPONENT;
public boolean isLigature()
Returns true if this is a ligature glyph.
return
true if this is a ligature glyph; false otherwise.
return (glyphType & 0x3) == LIGATURE;
public boolean isStandard()
Returns true if this is a standard glyph.
return
true if this is a standard glyph; false otherwise.
return (glyphType & 0x3) == STANDARD;
public boolean isWhitespace()
Returns true if this is a whitespace glyph.
return
true if this is a whitespace glyph; false otherwise.
return (glyphType & 0x4) == WHITESPACE;