public abstract class FontMetrics extends Object implements Serializable
FontMetrics
class defines a font metrics object, which
encapsulates information about the rendering of a particular font on a
particular screen.
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):
Note that the implementations of these methods are inefficient, so they are usually overridden with more efficient toolkit-specific implementations.
When an application asks 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.
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
character array. The advance of a String
is the
distance along the baseline of the String
. This
distance is the width that should be used for centering or
right-aligning the String
.
Note that the advance of a String
is not necessarily
the sum of the advances of its characters measured in isolation
because the width of a character can vary depending on its context.
For example, in Arabic text, the shape of a character can change
in order to connect to other characters. Also, in some scripts,
certain character sequences can be represented by a single shape,
called a ligature. Measuring characters individually does
not account for these transformations.
Font metrics are baseline-relative, meaning that they are
generally independent of the rotation applied to the font (modulo
possible grid hinting effects). See Font
.
Font
,
Serialized FormModifier and Type | Field and Description |
---|---|
protected Font |
font
The actual
Font from which the font metrics are
created. |
Modifier | Constructor and Description |
---|---|
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 . |
Modifier and Type | Method and Description |
---|---|
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 codePoint)
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. |
FontRenderContext |
getFontRenderContext()
Gets the
FontRenderContext used by this
FontMetrics object to measure text. |
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)
|
LineMetrics |
getLineMetrics(String str,
int beginIndex,
int limit,
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 . |
public Font getFont()
Font
described by this
FontMetrics
object.Font
described by this
FontMetrics
object.public FontRenderContext getFontRenderContext()
FontRenderContext
used by this
FontMetrics
object to measure text.
Note that methods in this class which take a Graphics
parameter measure text using the FontRenderContext
of that Graphics
object, and not this
FontRenderContext
FontRenderContext
used by this
FontMetrics
object.public int getLeading()
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.Font
.getHeight()
,
getAscent()
,
getDescent()
public int getAscent()
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.Font
.getMaxAscent()
public int getDescent()
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.Font
.getMaxDescent()
public int getHeight()
getLeading()
,
getAscent()
,
getDescent()
public int getMaxAscent()
Font
described by this FontMetrics
object. No character
extends further above the font's baseline than this height.Font
.getAscent()
public int getMaxDescent()
Font
described by this FontMetrics
object. No character
extends further below the font's baseline than this height.Font
.getDescent()
@Deprecated public int getMaxDecent()
getMaxDescent()
.Font
.getMaxDescent()
public int getMaxAdvance()
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
string's baseline. The advance of a String
is
not necessarily the sum of the advances of its characters.Font
, or -1
if the
maximum advance width is not known.public int charWidth(int codePoint)
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
character's baseline. Note that the advance of a
String
is not necessarily the sum of the advances
of its characters.
This method doesn't validate the specified character to be a
valid Unicode code point. The caller must validate the
character value using Character.isValidCodePoint
if necessary.
codePoint
- the character (Unicode code point) to be measuredFont
described by this
FontMetrics
object.charsWidth(char[], int, int)
,
stringWidth(String)
public int charWidth(char ch)
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
character's baseline. Note that the advance of a
String
is not necessarily the sum of the advances
of its characters.
Note: This method cannot handle supplementary
characters. To support all Unicode characters, including
supplementary characters, use the charWidth(int)
method.
ch
- the character to be measuredFont
described by this
FontMetrics
object.charsWidth(char[], int, int)
,
stringWidth(String)
public int stringWidth(String str)
String
in this Font
. The advance
is the distance from the leftmost point to the rightmost point
on the string's baseline.
Note that the advance of a String
is
not necessarily the sum of the advances of its characters.
str
- the String
to be measuredString
in the Font
described by this
FontMetrics
.NullPointerException
- if str is null.bytesWidth(byte[], int, int)
,
charsWidth(char[], int, int)
,
getStringBounds(String, Graphics)
public int charsWidth(char[] data, int off, int len)
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
string's baseline. The advance of a String
is not necessarily the sum of the advances of its characters.
This is equivalent to measuring a String
of the
characters in the specified range.data
- the array of characters to be measuredoff
- the start offset of the characters in the arraylen
- the number of characters to be measured from the arraychar
array in the font described by
this FontMetrics
object.NullPointerException
- if data
is null.IndexOutOfBoundsException
- if the off
and len
arguments index characters outside
the bounds of the data
array.charWidth(int)
,
charWidth(char)
,
bytesWidth(byte[], int, int)
,
stringWidth(String)
public int bytesWidth(byte[] data, int off, int len)
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
string's baseline. The advance of a String
is not necessarily the sum of the advances of its characters.
This is equivalent to measuring a String
of the
characters in the specified range.data
- the array of bytes to be measuredoff
- the start offset of the bytes in the arraylen
- the number of bytes to be measured from the arraybyte
array in the Font
described by
this FontMetrics
object.NullPointerException
- if data
is null.IndexOutOfBoundsException
- if the off
and len
arguments index bytes outside
the bounds of the data
array.charsWidth(char[], int, int)
,
stringWidth(String)
public int[] getWidths()
Font
. The advance is the
distance from the leftmost point to the rightmost point on the
character's baseline. Note that the advance of a
String
is not necessarily the sum of the advances
of its characters.Font
described by this FontMetrics
object.public boolean hasUniformLineMetrics()
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.true
if the font has uniform line metrics;
false
otherwise.Font.hasUniformLineMetrics()
public LineMetrics getLineMetrics(String str, Graphics context)
str
- the specified String
context
- the specified Graphics
contextLineMetrics
object created with the
specified String
and Graphics
context.Font.getLineMetrics(String, FontRenderContext)
public LineMetrics getLineMetrics(String str, int beginIndex, int limit, Graphics context)
str
- the specified String
beginIndex
- the initial offset of str
limit
- the end offset of str
context
- the specified Graphics
contextLineMetrics
object created with the
specified String
and Graphics
context.Font.getLineMetrics(String, int, int, FontRenderContext)
public LineMetrics getLineMetrics(char[] chars, int beginIndex, int limit, Graphics context)
LineMetrics
object for the specified
character array in the specified Graphics
context.chars
- the specified character arraybeginIndex
- the initial offset of chars
limit
- the end offset of chars
context
- the specified Graphics
contextLineMetrics
object created with the
specified character array and Graphics
context.Font.getLineMetrics(char[], int, int, FontRenderContext)
public LineMetrics getLineMetrics(CharacterIterator ci, int beginIndex, int limit, Graphics context)
LineMetrics
object for the specified
CharacterIterator
in the specified Graphics
context.ci
- the specified CharacterIterator
beginIndex
- the initial offset in ci
limit
- the end index of ci
context
- the specified Graphics
contextLineMetrics
object created with the
specified arguments.Font.getLineMetrics(CharacterIterator, int, int, FontRenderContext)
public Rectangle2D getStringBounds(String str, Graphics context)
String
in the
specified Graphics
context. The bounds is used
to layout the String
.
Note: The returned bounds is in baseline-relative coordinates
(see class notes
).
str
- the specified String
context
- the specified Graphics
contextRectangle2D
that is the bounding box of the
specified String
in the specified
Graphics
context.Font.getStringBounds(String, FontRenderContext)
public Rectangle2D getStringBounds(String str, int beginIndex, int limit, Graphics context)
String
in the
specified Graphics
context. The bounds is used
to layout the String
.
Note: The returned bounds is in baseline-relative coordinates
(see class notes
).
str
- the specified String
beginIndex
- the offset of the beginning of str
limit
- the end offset of str
context
- the specified Graphics
contextRectangle2D
that is the bounding box of the
specified String
in the specified
Graphics
context.Font.getStringBounds(String, int, int, FontRenderContext)
public Rectangle2D getStringBounds(char[] chars, int beginIndex, int limit, Graphics context)
Graphics
context.
The bounds is used to layout the String
created with the specified array of characters,
beginIndex
and limit
.
Note: The returned bounds is in baseline-relative coordinates
(see class notes
).
chars
- an array of charactersbeginIndex
- the initial offset of the array of
characterslimit
- the end offset of the array of characterscontext
- the specified Graphics
contextRectangle2D
that is the bounding box of the
specified character array in the specified
Graphics
context.Font.getStringBounds(char[], int, int, FontRenderContext)
public Rectangle2D getStringBounds(CharacterIterator ci, int beginIndex, int limit, Graphics context)
CharacterIterator
in the
specified Graphics
context.
Note: The returned bounds is in baseline-relative coordinates
(see class notes
).
ci
- the specified CharacterIterator
beginIndex
- the initial offset in ci
limit
- the end index of ci
context
- the specified Graphics
contextRectangle2D
that is the bounding box of the
characters indexed in the specified CharacterIterator
in the specified Graphics
context.Font.getStringBounds(CharacterIterator, int, int, FontRenderContext)
public Rectangle2D getMaxCharBounds(Graphics context)
Graphics
context.context
- the specified Graphics
contextRectangle2D
that is the
bounding box for the character with the maximum bounds.Font.getMaxCharBounds(FontRenderContext)
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2016, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.