java.lang.Object | |
↳ | java.awt.FontMetrics |
Known Direct Subclasses |
The 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
.
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
font | The actual Font from which the font metrics are
created. |
Protected Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Creates a new
FontMetrics object for finding out
height and width information about the specified Font
and specific character glyphs in that Font . |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Returns the total advance width for showing the specified array
of bytes in this
Font . | |||||||||||
Returns the advance width of the specified character in this
Font . | |||||||||||
Returns the advance width of the specified character in this
Font . | |||||||||||
Returns the total advance width for showing the specified array
of characters in this
Font . | |||||||||||
Determines the font ascent of the
Font
described by this FontMetrics object. | |||||||||||
Determines the font descent of the
Font
described by this
FontMetrics object. | |||||||||||
Gets the
Font described by this
FontMetrics object. | |||||||||||
Gets the
FontRenderContext used by this
FontMetrics object to measure text. | |||||||||||
Gets the standard height of a line of text in this font.
| |||||||||||
Determines the standard leading of the
Font described by this FontMetrics
object. | |||||||||||
Returns the
LineMetrics object for the specified
CharacterIterator in the specified Graphics
context. | |||||||||||
Returns the
LineMetrics object for the specified
character array in the specified Graphics context. | |||||||||||
Gets the maximum advance width of any character in this
Font . | |||||||||||
Determines the maximum ascent of the
Font
described by this FontMetrics object. | |||||||||||
Returns the bounds for the character with the maximum bounds
in the specified
Graphics context. | |||||||||||
This method is deprecated.
As of JDK version 1.1.1,
replaced by
getMaxDescent() .
| |||||||||||
Determines the maximum descent of the
Font
described by this FontMetrics object. | |||||||||||
Returns the bounds of the specified array of characters
in the specified
Graphics context. | |||||||||||
Returns the bounds of the specified
String in the
specified Graphics context. | |||||||||||
Returns the bounds of the specified
String in the
specified Graphics context. | |||||||||||
Returns the bounds of the characters indexed in the specified
CharacterIterator in the
specified Graphics context. | |||||||||||
Gets the advance widths of the first 256 characters in the
Font . | |||||||||||
Checks to see if the
Font has uniform line metrics. | |||||||||||
Returns the total advance width for showing the specified
String in this Font . | |||||||||||
Returns a representation of this
FontMetrics
object's values as a String . |
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
|
Creates a new FontMetrics
object for finding out
height and width information about the specified Font
and specific character glyphs in that Font
.
font | the Font |
---|
Returns the total advance width for showing the specified array
of bytes in this 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 measured |
---|---|
off | the start offset of the bytes in the array |
len | the number of bytes to be measured from the array |
byte
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. |
Returns the advance width of the specified character in this
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 measured |
---|
Font
described by this
FontMetrics
object.Returns the advance width of the specified character in this
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 measured |
---|
Font
described by this
FontMetrics
object.Returns the total advance width for showing the specified array
of characters in this 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 measured |
---|---|
off | the start offset of the characters in the array |
len | the number of characters to be measured from the array |
char
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. |
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.
Font
.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.
Font
.Gets the Font
described by this
FontMetrics
object.
Font
described by this
FontMetrics
object.
Gets the 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.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. Due to rounding this may not be the same as getAscent() + getDescent() + getLeading(). 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.
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.
Font
.Returns the 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 context |
LineMetrics
object created with the
specified arguments.Returns the LineMetrics
object for the specified
String
in the specified Graphics
context.
str | the specified String |
---|---|
beginIndex | the initial offset of str |
limit | the end offset of str |
context | the specified Graphics context |
LineMetrics
object created with the
specified String
and Graphics
context.Returns the LineMetrics
object for the specified
character array in the specified Graphics
context.
chars | the specified character array |
---|---|
beginIndex | the initial offset of chars |
limit | the end offset of chars |
context | the specified Graphics context |
LineMetrics
object created with the
specified character array and Graphics
context.Returns the LineMetrics
object for the specified
String
in the specified Graphics
context.
str | the specified String |
---|---|
context | the specified Graphics context |
LineMetrics
object created with the
specified String
and Graphics
context.Gets the maximum advance width of any character in this
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.
Determines the maximum ascent of the Font
described by this FontMetrics
object. No character
extends further above the font's baseline than this height.
Font
.Returns the bounds for the character with the maximum bounds
in the specified Graphics
context.
context | the specified Graphics context |
---|
Rectangle2D
that is the
bounding box for the character with the maximum bounds.
This method is deprecated.
As of JDK version 1.1.1,
replaced by getMaxDescent()
.
For backward compatibility only.
Font
.Determines the maximum descent of the Font
described by this FontMetrics
object. No character
extends further below the font's baseline than this height.
Font
.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
.
Note: The returned bounds is in baseline-relative coordinates
(see class notes
).
chars | an array of characters |
---|---|
beginIndex | the initial offset of the array of characters |
limit | the end offset of the array of characters |
context | the specified Graphics context |
Rectangle2D
that is the bounding box of the
specified character array in the specified
Graphics
context.Returns the bounds of the specified 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 context |
Rectangle2D
that is the bounding box of the
specified String
in the specified
Graphics
context.Returns the bounds of the specified 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 context |
Rectangle2D
that is the bounding box of the
specified String
in the specified
Graphics
context.Returns the bounds of the characters indexed in the specified
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 context |
Rectangle2D
that is the bounding box of the
characters indexed in the specified CharacterIterator
in the specified Graphics
context.Gets the advance widths of the first 256 characters in the
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.
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.
true
if the font has uniform line metrics;
false
otherwise.Returns the total advance width for showing the specified
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 measured |
---|
String
in the Font
described by this
FontMetrics
.NullPointerException | if str is null. |
---|
Returns a representation of this FontMetrics
object's values as a String
.
String
representation of this
FontMetrics
object.