Module java.desktop
Package java.awt.font

Class GlyphMetrics

java.lang.Object
java.awt.font.GlyphMetrics

public final class GlyphMetrics extends Object
The GlyphMetrics class represents information 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 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 Also: