Caret
Interface Caret
- All Known Implementing Classes:
- BasicTextUI.BasicCaret, DefaultCaret
public interface Caret
A place within a document view that represents where things can be inserted into the document model. A caret has a position in the document referred to as a dot. The dot is where the caret is currently located in the model. There is a second position maintained by the caret that represents the other end of a selection called mark. If there is no selection the dot and mark will be equal. If a selection exists, the two values will be different.
The dot can be placed by either calling setDot
or moveDot
. Setting the dot has the effect of removing any selection that may have previously existed. The dot and mark will be equal. Moving the dot has the effect of creating a selection as the mark is left at whatever position it previously had.
Methods
install
void install(JTextComponent c)
Called when the UI is being installed into the interface of a JTextComponent. This can be used to gain access to the model that is being navigated by the implementation of this interface.
- Parameters:
-
c
- the JTextComponent
deinstall
void deinstall(JTextComponent c)
Called when the UI is being removed from the interface of a JTextComponent. This is used to unregister any listeners that were attached.
- Parameters:
-
c
- the JTextComponent
paint
void paint(Graphics g)
Renders the caret. This method is called by UI classes.
- Parameters:
-
g
- the graphics context
addChangeListener
void addChangeListener(ChangeListener l)
Adds a listener to track whenever the caret position has been changed.
- Parameters:
-
l
- the change listener
removeChangeListener
void removeChangeListener(ChangeListener l)
Removes a listener that was tracking caret position changes.
- Parameters:
-
l
- the change listener
isVisible
boolean isVisible()
Determines if the caret is currently visible.
- Returns:
- true if the caret is visible else false
setVisible
void setVisible(boolean v)
Sets the visibility of the caret.
- Parameters:
-
v
- true if the caret should be shown, and false if the caret should be hidden
isSelectionVisible
boolean isSelectionVisible()
Determines if the selection is currently visible.
- Returns:
- true if the caret is visible else false
setSelectionVisible
void setSelectionVisible(boolean v)
Sets the visibility of the selection
- Parameters:
-
v
- true if the caret should be shown, and false if the caret should be hidden
setMagicCaretPosition
void setMagicCaretPosition(Point p)
Set the current caret visual location. This can be used when moving between lines that have uneven end positions (such as when caret up or down actions occur). If text flows left-to-right or right-to-left the x-coordinate will indicate the desired navigation location for vertical movement. If the text flow is top-to-bottom, the y-coordinate will indicate the desired navigation location for horizontal movement.
- Parameters:
-
p
- the Point to use for the saved position. This can be null to indicate there is no visual location.
getMagicCaretPosition
Point getMagicCaretPosition()
Gets the current caret visual location.
- Returns:
- the visual position.
- See Also:
setMagicCaretPosition(java.awt.Point)
setBlinkRate
void setBlinkRate(int rate)
Sets the blink rate of the caret. This determines if and how fast the caret blinks, commonly used as one way to attract attention to the caret.
- Parameters:
-
rate
- the delay in milliseconds >=0. If this is zero the caret will not blink.
getBlinkRate
int getBlinkRate()
Gets the blink rate of the caret. This determines if and how fast the caret blinks, commonly used as one way to attract attention to the caret.
- Returns:
- the delay in milliseconds >=0. If this is zero the caret will not blink.
getDot
int getDot()
Fetches the current position of the caret.
- Returns:
- the position >=0
getMark
int getMark()
Fetches the current position of the mark. If there is a selection, the mark will not be the same as the dot.
- Returns:
- the position >=0
setDot
void setDot(int dot)
Sets the caret position to some position. This causes the mark to become the same as the dot, effectively setting the selection range to zero.
If the parameter is negative or beyond the length of the document, the caret is placed at the beginning or at the end, respectively.
- Parameters:
-
dot
- the new position to set the caret to
moveDot
void moveDot(int dot)
Moves the caret position (dot) to some other position, leaving behind the mark. This is useful for making selections.
- Parameters:
-
dot
- the new position to move the caret to >=0
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