Class TextMeasurer
- All Implemented Interfaces:
Cloneable
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).
- Since:
- 1.3
- See Also:
-
Constructor Summary
ConstructorDescriptionConstructs aTextMeasurer
from the source text. -
Method Summary
Modifier and TypeMethodDescriptionprotected Object
clone()
Creates and returns a copy of this object.void
deleteChar
(AttributedCharacterIterator newParagraph, int deletePos) Updates theTextMeasurer
after a single character has been deleted from the paragraph currently represented by thisTextMeasurer
.float
getAdvanceBetween
(int start, int limit) Returns the graphical width of a line beginning atstart
and including characters up tolimit
.getLayout
(int start, int limit) Returns aTextLayout
on the given character range.int
getLineBreakIndex
(int start, float maxAdvance) Returns the index of the first character which will not fit on on a line beginning atstart
and possible measuring up tomaxAdvance
in graphical width.void
insertChar
(AttributedCharacterIterator newParagraph, int insertPos) Updates theTextMeasurer
after a single character has been inserted into the paragraph currently represented by thisTextMeasurer
.
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Constructor Details
-
TextMeasurer
Constructs aTextMeasurer
from the source text. The source text should be a single entire paragraph.- Parameters:
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.
-
-
Method Details
-
clone
Description copied from class:Object
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 objectx
, the expression:x.clone() != x
x.clone().getClass() == x.getClass()
true
, but these are not absolute requirements. While it is typically the case that:x.clone().equals(x)
true
, this is not an absolute requirement.By convention, the returned object should be obtained by calling
super.clone
. If a class and all of its superclasses (exceptObject
) obey this convention, it will be the case thatx.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 bysuper.clone
need to be modified. -
getLineBreakIndex
public int getLineBreakIndex(int start, float maxAdvance) Returns the index of the first character which will not fit on on a line beginning atstart
and possible measuring up tomaxAdvance
in graphical width.- Parameters:
start
- the character index at which to start measuring.start
is an absolute index, not relative to the start of the paragraphmaxAdvance
- the graphical width in which the line must fit- Returns:
- the index after the last character that will fit
on a line beginning at
start
, which is not longer thanmaxAdvance
in graphical width - Throws:
IllegalArgumentException
- ifstart
is less than the beginning of the paragraph.
-
getAdvanceBetween
public float getAdvanceBetween(int start, int limit) Returns the graphical width of a line beginning atstart
and including characters up tolimit
.start
andlimit
are absolute indices, not relative to the start of the paragraph.- Parameters:
start
- the character index at which to start measuringlimit
- the character index at which to stop measuring- Returns:
- the graphical width of a line beginning at
start
and including characters up tolimit
- Throws:
IndexOutOfBoundsException
- iflimit
is less thanstart
IllegalArgumentException
- ifstart
orlimit
is not between the beginning of the paragraph and the end of the paragraph.
-
getLayout
Returns aTextLayout
on the given character range.- Parameters:
start
- the index of the first characterlimit
- the index after the last character. Must be greater thanstart
- Returns:
- a
TextLayout
for the characters beginning atstart
up to (but not including)limit
- Throws:
IndexOutOfBoundsException
- iflimit
is less thanstart
IllegalArgumentException
- ifstart
orlimit
is not between the beginning of the paragraph and the end of the paragraph.
-
insertChar
Updates theTextMeasurer
after a single character has been inserted into the paragraph currently represented by thisTextMeasurer
. After this call, thisTextMeasurer
is equivalent to a newTextMeasurer
created from the text; however, it will usually be more efficient to update an existingTextMeasurer
than to create a new one from scratch.- Parameters:
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 ofnewParagraph
, and must be less than the end ofnewParagraph
.- Throws:
IndexOutOfBoundsException
- ifinsertPos
is less than the start ofnewParagraph
or greater than or equal to the end ofnewParagraph
NullPointerException
- ifnewParagraph
isnull
-
deleteChar
Updates theTextMeasurer
after a single character has been deleted from the paragraph currently represented by thisTextMeasurer
. After this call, thisTextMeasurer
is equivalent to a newTextMeasurer
created from the text; however, it will usually be more efficient to update an existingTextMeasurer
than to create a new one from scratch.- Parameters:
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 ofnewParagraph
, and must not be greater than the end ofnewParagraph
.- Throws:
IndexOutOfBoundsException
- ifdeletePos
is less than the start ofnewParagraph
or greater than the end ofnewParagraph
NullPointerException
- ifnewParagraph
isnull
-