java.lang.Object | |
↳ | java.awt.font.TextMeasurer |
The TextMeasurer
class provides the primitive operations
needed for line break: measuring up to a given advance, determining the
advance of a range of characters, and generating a
TextLayout
for a range of characters. It also provides
methods for incremental editing of paragraphs.
A TextMeasurer
object is constructed with an
AttributedCharacterIterator
representing a single paragraph of text. The value returned by the
getBeginIndex
method of AttributedCharacterIterator
defines the absolute index of the first character. The value
returned by the
getEndIndex
method of AttributedCharacterIterator
defines the index
past the last character. These values define the range of indexes to
use in calls to the TextMeasurer
. For example, calls to
get the advance of a range of text or the line break of a range of text
must use indexes between the beginning and end index values. Calls to
insertChar
and
deleteChar
reset the TextMeasurer
to use the beginning index and end
index of the AttributedCharacterIterator
passed in those calls.
Most clients will use the more convenient LineBreakMeasurer
,
which implements the standard line break policy (placing as many words
as will fit on each line).
Public Constructors | |||||||||||
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Constructs a
TextMeasurer from the source text. |
Public Methods | |||||||||||
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Updates the
TextMeasurer after a single character has
been deleted
from the paragraph currently represented by this
TextMeasurer . | |||||||||||
Returns the graphical width of a line beginning at
start
and including characters up to limit . | |||||||||||
Returns a
TextLayout on the given character range. | |||||||||||
Returns the index of the first character which will not fit on
on a line beginning at
start and possible
measuring up to maxAdvance in graphical width. | |||||||||||
Updates the
TextMeasurer after a single character has
been inserted
into the paragraph currently represented by this
TextMeasurer . |
Protected Methods | |||||||||||
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Creates and returns a copy of this object.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
|
Constructs a TextMeasurer
from the source text.
The source text should be a single entire paragraph.
text | the source paragraph. Cannot be null. |
---|---|
frc | the information about a graphics device which is needed to measure the text correctly. Cannot be null. |
Updates the TextMeasurer
after a single character has
been deleted
from the paragraph currently represented by this
TextMeasurer
. After this call, this
TextMeasurer
is equivalent to a new TextMeasurer
created from the text; however, it will usually be more efficient
to update an existing TextMeasurer
than to create a new one
from scratch.
newParagraph | the text of the paragraph after performing the deletion. Cannot be null. |
---|---|
deletePos | the position in the text where the character was removed.
Must not be less than
the start of newParagraph , and must not be greater than the
end of newParagraph . |
IndexOutOfBoundsException | if deletePos is
less than the start of newParagraph or greater
than the end of newParagraph |
---|---|
NullPointerException | if newParagraph is
null
|
Returns the graphical width of a line beginning at start
and including characters up to limit
.
start
and limit
are absolute indices,
not relative to the start of the paragraph.
start | the character index at which to start measuring |
---|---|
limit | the character index at which to stop measuring |
start
and including characters up to limit
IndexOutOfBoundsException | if limit is less
than start |
---|---|
IllegalArgumentException | if start or
limit is not between the beginning of
the paragraph and the end of the paragraph.
|
Returns a TextLayout
on the given character range.
start | the index of the first character |
---|---|
limit | the index after the last character. Must be greater
than start |
TextLayout
for the characters beginning at
start
up to (but not including) limit
IndexOutOfBoundsException | if limit is less
than start |
---|---|
IllegalArgumentException | if start or
limit is not between the beginning of
the paragraph and the end of the paragraph.
|
Returns the index of the first character which will not fit on
on a line beginning at start
and possible
measuring up to maxAdvance
in graphical width.
start | the character index at which to start measuring.
start is an absolute index, not relative to the
start of the paragraph |
---|---|
maxAdvance | the graphical width in which the line must fit |
start
, which is not longer
than maxAdvance
in graphical widthIllegalArgumentException | if start is
less than the beginning of the paragraph.
|
---|
Updates the TextMeasurer
after a single character has
been inserted
into the paragraph currently represented by this
TextMeasurer
. After this call, this
TextMeasurer
is equivalent to a new
TextMeasurer
created from the text; however, it will
usually be more efficient to update an existing
TextMeasurer
than to create a new one from scratch.
newParagraph | the text of the paragraph after performing the insertion. Cannot be null. |
---|---|
insertPos | the position in the text where the character was
inserted. Must not be less than the start of
newParagraph , and must be less than the end of
newParagraph . |
IndexOutOfBoundsException | if insertPos is less
than the start of newParagraph or greater than
or equal to the end of newParagraph |
---|---|
NullPointerException | if newParagraph is
null
|
Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:
will be true, and that the expression:x.clone() != x
will be true, but these are not absolute requirements. While it is typically the case that:x.clone().getClass() == x.getClass()
will be true, this is not an absolute requirement.x.clone().equals(x)
By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().
By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.
The method clone for class Object performs a specific cloning operation. First, if the class of this object does not implement the interface Cloneable, then a CloneNotSupportedException is thrown. Note that all arrays are considered to implement the interface Cloneable. Otherwise, this method creates a new instance of the class of this object and initializes all its fields with exactly the contents of the corresponding fields of this object, as if by assignment; the contents of the fields are not themselves cloned. Thus, this method performs a "shallow copy" of this object, not a "deep copy" operation.
The class Object does not itself implement the interface Cloneable, so calling the clone method on an object whose class is Object will result in throwing an exception at run time.