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

Overview

Package

Class

Use

Tree

Deprecated

Index

Help

Java^TM 2 Platform
Standard Edition

PREV CLASS NEXT CLASS

FRAMES NO FRAMES

SUMMARY: INNER | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

java.awt
Class FontMetrics

java.lang.Object
  |
  +--java.awt.FontMetrics

public abstract class FontMetrics
extends Object
implements Serializable

The FontMetrics class defines a font metrics object, which encapsulates information about the rendering of a particular font on a particular screen. Note that the implementations of these methods are inefficient, so they are usually overridden with more efficient toolkit-specific implementations.

Note to subclassers: Since many of these methods form closed, mutually recursive loops, you must take care that you implement at least one of the methods in each such loop to prevent infinite recursion when your subclass is used. In particular, the following is the minimal suggested set of methods to override in order to ensure correctness and prevent infinite recursion (though other subsets are equally feasible):

When an application asks AWT to place a character at the position (x, y), the character is placed so that its reference point (shown as the dot in the accompanying image) is put at that position. The reference point specifies a horizontal line called the baseline of the character. In normal printing, the baselines of characters should align.

In addition, every character in a font has an ascent, a descent, and an advance width. The ascent is the amount by which the character ascends above the baseline. The descent is the amount by which the character descends below the baseline. The advance width indicates the position at which AWT should place the next character.

If the current character is placed with its reference point at the position (x, y), and the character's advance width is w, then the new character is placed with its reference point at the position (x + w, y). The advance width is often, but not necessarily, the same as the width of a character's bounding box. In particular, oblique and italic fonts often have characters whose top-right corner extends slightly beyond the advance width.

An array of characters or a string can also have an ascent, a descent, and an advance width. The ascent of the array is the maximum ascent of any character in the array. The descent is the maximum descent of any character in the array. The advance width is the sum of the advance widths of each of the characters in the array.

Since:: JDK1.0
See Also:: Font, Serialized Form

Field Summary

protected Font font
          The actual Font from which the font metrics are created.

Constructor Summary

protected FontMetrics(Font font)
          Creates a new FontMetrics object for finding out height and width information about the specified Font and specific character glyphs in that Font.

Method Summary

int bytesWidth(byte[] data, int off, int len)
          Returns the total advance width for showing the specified array of bytes in this Font.

int charsWidth(char[] data, int off, int len)
          Returns the total advance width for showing the specified array of characters in this Font.

int charWidth(char ch)
          Returns the advance width of the specified character in this Font.

int charWidth(int ch)
          Returns the advance width of the specified character in this Font.

int getAscent()
          Determines the font ascent of the Font described by this FontMetrics object.

int getDescent()
          Determines the font descent of the Font described by this FontMetrics object.

Font getFont()
          Gets the Font described by this FontMetrics object.

int getHeight()
          Gets the standard height of a line of text in this font.

int getLeading()
          Determines the standard leading of the Font described by this FontMetrics object.

LineMetrics getLineMetrics(char[] chars, int beginIndex, int limit, Graphics context)
          Returns the LineMetrics object for the specified character array in the specified Graphics context.

LineMetrics getLineMetrics(CharacterIterator ci, int beginIndex, int limit, Graphics context)
          Returns the LineMetrics object for the specified CharacterIterator in the specified Graphics context.

LineMetrics getLineMetrics(String str, Graphics context)
          Returns the LineMetrics object for the specified String in the specified Graphics context.

LineMetrics getLineMetrics(String str, int beginIndex, int limit, Graphics context)
          Returns the LineMetrics object for the specified String in the specified Graphics context.

int getMaxAdvance()
          Gets the maximum advance width of any character in this Font.

int getMaxAscent()
          Determines the maximum ascent of the Font described by this FontMetrics object.

Rectangle2D getMaxCharBounds(Graphics context)
          Returns the bounds for the character with the maximum bounds in the specified Graphics context.

int getMaxDecent()
          Deprecated. As of JDK version 1.1.1, replaced by getMaxDescent().

int getMaxDescent()
          Determines the maximum descent of the Font described by this FontMetrics object.

Rectangle2D getStringBounds(char[] chars, int beginIndex, int limit, Graphics context)
          Returns the bounds of the specified array of characters in the specified Graphics context.

Rectangle2D getStringBounds(CharacterIterator ci, int beginIndex, int limit, Graphics context)
          Returns the bounds of the characters indexed in the specified CharacterIterator in the specified Graphics context.

Rectangle2D getStringBounds(String str, Graphics context)
          Returns the bounds of the specified String in the specified Graphics context.

Rectangle2D getStringBounds(String str, int beginIndex, int limit, Graphics context)
          Returns the bounds of the specified String in the specified Graphics context.

int[] getWidths()
          Gets the advance widths of the first 256 characters in the Font.

boolean hasUniformLineMetrics()
          Checks to see if the Font has uniform line metrics.

int stringWidth(String str)
          Returns the total advance width for showing the specified String in this Font.

String toString()
          Returns a representation of this FontMetrics object's values as a String.

Methods inherited from class java.lang.Object

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

Field Detail

font

protected Font font

The actual Font from which the font metrics are created. This cannot be null.

See Also:: getFont()

Constructor Detail

FontMetrics

protected FontMetrics(Font font)

Creates a new FontMetrics object for finding out height and width information about the specified Font and specific character glyphs in that Font.

Parameters:: font - the Font
See Also:: Font

Method Detail

getFont

public Font getFont()

Gets the Font described by this FontMetrics object.

Returns:: the Font described by this FontMetrics object.

getLeading

public int getLeading()

Determines the standard leading of the Font described by this FontMetrics object. The standard leading, or interline spacing, is the logical amount of space to be reserved between the descent of one line of text and the ascent of the next line. The height metric is calculated to include this extra space.

Returns:: the standard leading of the Font.
See Also:: getHeight(), getAscent(), getDescent()

getAscent

public int getAscent()

Determines the font ascent of the Font described by this FontMetrics object. The font ascent is the distance from the font's baseline to the top of most alphanumeric characters. Some characters in the Font might extend above the font ascent line.

Returns:: the font ascent of the Font.
See Also:: getMaxAscent()

getDescent

public int getDescent()

Determines the font descent of the Font described by this FontMetrics object. The font descent is the distance from the font's baseline to the bottom of most alphanumeric characters with descenders. Some characters in the Font might extend below the font descent line.

Returns:: the font descent of the Font.
See Also:: getMaxDescent()

getHeight

public int getHeight()

Gets the standard height of a line of text in this font. This is the distance between the baseline of adjacent lines of text. It is the sum of the leading + ascent + descent. There is no guarantee that lines of text spaced at this distance are disjoint; such lines may overlap if some characters overshoot either the standard ascent or the standard descent metric.

Returns:: the standard height of the font.
See Also:: getLeading(), getAscent(), getDescent()

getMaxAscent

public int getMaxAscent()

Determines the maximum ascent of the Font described by this FontMetrics object. No character extends further above the font's baseline than this height.

Returns:: the maximum ascent of any character in the Font.
See Also:: getAscent()

getMaxDescent

public int getMaxDescent()

Determines the maximum descent of the Font described by this FontMetrics object. No character extends further below the font's baseline than this height.

Returns:: the maximum descent of any character in the Font.
See Also:: getDescent()

getMaxDecent

public int getMaxDecent()

Deprecated. As of JDK version 1.1.1, replaced by getMaxDescent().

For backward compatibility only.

See Also:: getMaxDescent()

getMaxAdvance

public int getMaxAdvance()

Gets the maximum advance width of any character in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Returns:: the maximum advance width of any character in the Font, or -1 if the maximum advance width is not known.

charWidth

public int charWidth(int ch)

Returns the advance width of the specified character in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Parameters:: ch - the character to be measured
Returns:: the advance width of the specified char in the Font described by this FontMetrics object.
See Also:: charsWidth(char[], int, int), stringWidth(String)

charWidth

public int charWidth(char ch)

Returns the advance width of the specified character in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Parameters:: ch - the character to be measured
Returns:: the advance width of the specified char in the Font described by this FontMetrics object.
See Also:: charsWidth(char[], int, int), stringWidth(String)

stringWidth

public int stringWidth(String str)

Returns the total advance width for showing the specified String in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Parameters:: str - the String to be measured
Returns:: the advance width of the specified String in the Font described by this FontMetrics.
See Also:: bytesWidth(byte[], int, int), charsWidth(char[], int, int)

charsWidth

public int charsWidth(char[] data,
                      int off,
                      int len)

Returns the total advance width for showing the specified array of characters in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Parameters:: data - the array of characters to be measured; off - the start offset of the characters in the array; len - the number of characters to be measured from the array
Returns:: the advance width of the subarray of the specified char array in the font described by this FontMetrics object.
See Also:: charWidth(int), charWidth(char), bytesWidth(byte[], int, int), stringWidth(String)

bytesWidth

public int bytesWidth(byte[] data,
                      int off,
                      int len)

Returns the total advance width for showing the specified array of bytes in this Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Parameters:: data - the array of bytes to be measured; off - the start offset of the bytes in the array; len - the number of bytes to be measured from the array
Returns:: the advance width of the subarray of the specified byte array in the Font described by this FontMetrics object.
See Also:: charsWidth(char[], int, int), stringWidth(String)

getWidths

public int[] getWidths()

Gets the advance widths of the first 256 characters in the Font. The advance width is the amount by which the current point is moved from one character to the next in a line of text.

Returns:: an array storing the advance widths of the characters in the Font described by this FontMetrics object.

hasUniformLineMetrics

public boolean hasUniformLineMetrics()

Checks to see if the Font has uniform line metrics. A composite font may consist of several different fonts to cover various character sets. In such cases, the FontLineMetrics objects are not uniform. Different fonts may have a different ascent, descent, metrics and so on. This information is sometimes necessary for line measuring and line breaking.

Returns:: true if the font has uniform line metrics; false otherwise.
See Also:: Font.hasUniformLineMetrics()

getLineMetrics

public LineMetrics getLineMetrics(String str,
                                  Graphics context)

Returns the LineMetrics object for the specified String in the specified Graphics context.

Parameters:: str - the specified String; context - the specified Graphics context
Returns:: a LineMetrics object created with the specified String and Graphics context.
See Also:: Font.getLineMetrics(String, FontRenderContext)

getLineMetrics

public LineMetrics getLineMetrics(String str,
                                  int beginIndex,
                                  int limit,
                                  Graphics context)

Returns the LineMetrics object for the specified String in the specified Graphics context.

Parameters:: str - the specified String; beginIndex - the initial offset of str; limit - the length of str; context - the specified Graphics context
Returns:: a LineMetrics object created with the specified String and Graphics context.
See Also:: Font.getLineMetrics(String, int, int, FontRenderContext)

getLineMetrics

public LineMetrics getLineMetrics(char[] chars,
                                  int beginIndex,
                                  int limit,
                                  Graphics context)

Returns the LineMetrics object for the specified character array in the specified Graphics context.

Parameters:: chars - the specified character array; beginIndex - the initial offset of chars; limit - the length of chars; context - the specified Graphics context
Returns:: a LineMetrics object created with the specified character array and Graphics context.
See Also:: Font.getLineMetrics(char[], int, int, FontRenderContext)

getLineMetrics

public LineMetrics getLineMetrics(CharacterIterator ci,
                                  int beginIndex,
                                  int limit,
                                  Graphics context)

Returns the LineMetrics object for the specified CharacterIterator in the specified Graphics context.

Parameters:: ci - the specified CharacterIterator; beginIndex - the initial offset in ci; limit - the end index of ci; context - the specified Graphics context
Returns:: a LineMetrics object created with the specified arguments.
See Also:: Font.getLineMetrics(CharacterIterator, int, int, FontRenderContext)

getStringBounds

public Rectangle2D getStringBounds(String str,
                                   Graphics context)

Returns the bounds of the specified String in the specified Graphics context. The bounds is used to layout the String.

Parameters:: str - the specified String; context - the specified Graphics context
Returns:: a Rectangle2D that is the bounding box of the specified String in the specified Graphics context.
See Also:: Font.getStringBounds(String, FontRenderContext)

getStringBounds

public Rectangle2D getStringBounds(String str,
                                   int beginIndex,
                                   int limit,
                                   Graphics context)

Returns the bounds of the specified String in the specified Graphics context. The bounds is used to layout the String.

Parameters:: str - the specified String; beginIndex - the offset of the beginning of str; limit - the length of str; context - the specified Graphics context
Returns:: a Rectangle2D that is the bounding box of the specified String in the specified Graphics context.
See Also:: Font.getStringBounds(String, int, int, FontRenderContext)

getStringBounds

public Rectangle2D getStringBounds(char[] chars,
                                   int beginIndex,
                                   int limit,
                                   Graphics context)

Returns the bounds of the specified array of characters in the specified Graphics context. The bounds is used to layout the String created with the specified array of characters, beginIndex and limit.

Parameters:: chars - an array of characters; beginIndex - the initial offset of the array of characters; limit - the length of the array of characters; context - the specified Graphics context
Returns:: a Rectangle2D that is the bounding box of the specified character array in the specified Graphics context.
See Also:: Font.getStringBounds(char[], int, int, FontRenderContext)

getStringBounds

public Rectangle2D getStringBounds(CharacterIterator ci,
                                   int beginIndex,
                                   int limit,
                                   Graphics context)

Returns the bounds of the characters indexed in the specified CharacterIterator in the specified Graphics context.

Parameters:: ci - the specified CharacterIterator; beginIndex - the initial offset in ci; limit - the end index of ci; context - the specified Graphics context
Returns:: a Rectangle2D that is the bounding box of the characters indexed in the specified CharacterIterator in the specified Graphics context.
See Also:: Font.getStringBounds(CharacterIterator, int, int, FontRenderContext)

getMaxCharBounds

public Rectangle2D getMaxCharBounds(Graphics context)

Returns the bounds for the character with the maximum bounds in the specified Graphics context.

Parameters:: context - the specified Graphics context
Returns:: a Rectangle2D that is the bounding box for the character with the maximum bounds.
See Also:: Font.getMaxCharBounds(FontRenderContext)

toString

public String toString()

Returns a representation of this FontMetrics object's values as a String.

Overrides:: toString in class Object

Returns:: a String representation of this FontMetrics object.
Since:: JDK1.0.

Overview

Package

Class

Use

Tree

Deprecated

Index

Help

Java^TM 2 Platform
Standard Edition

PREV CLASS NEXT CLASS

FRAMES NO FRAMES

SUMMARY: INNER | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

Submit a bug or feature
Java, Java 2D, and JDBC are a trademarks or registered trademarks of Sun Microsystems, Inc. in the US and other countries.
Copyright 1993-1999 Sun Microsystems, Inc. 901 San Antonio Road,
Palo Alto, California, 94303, U.S.A. All Rights Reserved.

Field Summary
`protected Font`	`font` The actual `Font` from which the font metrics are created.

Constructor Summary
`protected`	`FontMetrics(Font font)` Creates a new `FontMetrics` object for finding out height and width information about the specified `Font` and specific character glyphs in that `Font`.

Method Summary
`int`	`bytesWidth(byte[] data, int off, int len)` Returns the total advance width for showing the specified array of bytes in this `Font`.
`int`	`charsWidth(char[] data, int off, int len)` Returns the total advance width for showing the specified array of characters in this `Font`.
`int`	`charWidth(char ch)` Returns the advance width of the specified character in this `Font`.
`int`	`charWidth(int ch)` Returns the advance width of the specified character in this `Font`.
`int`	`getAscent()` Determines the font ascent of the `Font` described by this `FontMetrics` object.
`int`	`getDescent()` Determines the font descent of the `Font` described by this `FontMetrics` object.
`Font`	`getFont()` Gets the `Font` described by this `FontMetrics` object.
`int`	`getHeight()` Gets the standard height of a line of text in this font.
`int`	`getLeading()` Determines the standard leading of the `Font` described by this `FontMetrics` object.
`LineMetrics`	`getLineMetrics(char[] chars, int beginIndex, int limit, Graphics context)` Returns the `LineMetrics` object for the specified character array in the specified `Graphics` context.
`LineMetrics`	`getLineMetrics(CharacterIterator ci, int beginIndex, int limit, Graphics context)` Returns the `LineMetrics` object for the specified `CharacterIterator` in the specified `Graphics` context.
`LineMetrics`	`getLineMetrics(String str, Graphics context)` Returns the `LineMetrics` object for the specified `String` in the specified `Graphics` context.
`LineMetrics`	`getLineMetrics(String str, int beginIndex, int limit, Graphics context)` Returns the `LineMetrics` object for the specified `String` in the specified `Graphics` context.
`int`	`getMaxAdvance()` Gets the maximum advance width of any character in this `Font`.
`int`	`getMaxAscent()` Determines the maximum ascent of the `Font` described by this `FontMetrics` object.
`Rectangle2D`	`getMaxCharBounds(Graphics context)` Returns the bounds for the character with the maximum bounds in the specified `Graphics` context.
`int`	`getMaxDecent()` Deprecated. As of JDK version 1.1.1, replaced by `getMaxDescent()`.
`int`	`getMaxDescent()` Determines the maximum descent of the `Font` described by this `FontMetrics` object.
`Rectangle2D`	`getStringBounds(char[] chars, int beginIndex, int limit, Graphics context)` Returns the bounds of the specified array of characters in the specified `Graphics` context.
`Rectangle2D`	`getStringBounds(CharacterIterator ci, int beginIndex, int limit, Graphics context)` Returns the bounds of the characters indexed in the specified `CharacterIterator` in the specified `Graphics` context.
`Rectangle2D`	`getStringBounds(String str, Graphics context)` Returns the bounds of the specified `String` in the specified `Graphics` context.
`Rectangle2D`	`getStringBounds(String str, int beginIndex, int limit, Graphics context)` Returns the bounds of the specified `String` in the specified `Graphics` context.
`int[]`	`getWidths()` Gets the advance widths of the first 256 characters in the `Font`.
`boolean`	`hasUniformLineMetrics()` Checks to see if the `Font` has uniform line metrics.
`int`	`stringWidth(String str)` Returns the total advance width for showing the specified `String` in this `Font`.
`String`	`toString()` Returns a representation of this `FontMetrics` object's values as a `String`.

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

java.awt Class FontMetrics

font

FontMetrics

getFont

getLeading

getAscent

getDescent

getHeight

getMaxAscent

getMaxDescent

getMaxDecent

getMaxAdvance

charWidth

charWidth

stringWidth

charsWidth

bytesWidth

getWidths

hasUniformLineMetrics

getLineMetrics

getLineMetrics

getLineMetrics

getLineMetrics

getStringBounds

getStringBounds

getStringBounds

getStringBounds

getMaxCharBounds

toString

java.awt
Class FontMetrics