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JavaTM 2 Platform Std. Ed. v1.3 |
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java.lang.Object | +--java.awt.FontMetrics
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 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.
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, 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 |
protected Font font
Font from which the font metrics are
created.
This cannot be null.getFont()| Constructor Detail |
protected FontMetrics(Font font)
FontMetrics object for finding out
height and width information about the specified Font
and specific character glyphs in that Font.font - the FontFont| Method Detail |
public Font getFont()
Font described by this
FontMetrics object.Font described 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()public int getMaxDecent()
getMaxDescent().
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 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.ch - the character to be measuredchar
in the Font 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.char
in the Font 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 total advance width returned from this method
does not take into account the rendering context. Therefore,
the anti-aliasing and fractional metrics hints can affect the
value of the advance. When enabling the anti-aliasing and
fractional metrics hints, use
getStringBounds(String, Graphics)
instead of this method. 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.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.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.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)
LineMetrics object for the specified
String in the specified Graphics context.str - the specified Stringcontext - 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)
LineMetrics object for the specified
String in the specified Graphics context.str - the specified StringbeginIndex - the initial offset of strlimit - the length of strcontext - 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 charslimit - the length of charscontext - 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 CharacterIteratorbeginIndex - the initial offset in cilimit - the end index of cicontext - 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.str - the specified Stringcontext - 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.str - the specified StringbeginIndex - the offset of the beginning of strlimit - the length of strcontext - 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.chars - an array of charactersbeginIndex - the initial offset of the array of
characterslimit - the length 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.ci - the specified CharacterIteratorbeginIndex - the initial offset in cilimit - the end index of cicontext - 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)public String toString()
FontMetrics
object's values as a String.toString in class ObjectString representation of this
FontMetrics object.
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JavaTM 2 Platform Std. Ed. v1.3 |
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