API java : NavigationFilter

javax.swing.text
Class NavigationFilter

java.lang.Object
  javax.swing.text.NavigationFilter

public class NavigationFilter
extends Object

NavigationFilter can be used to restrict where the cursor can be positioned. When the default cursor positioning actions attempt to reposition the cursor they will call into the NavigationFilter, assuming the JTextComponent has a non-null NavigationFilter set. In this manner the NavigationFilter can effectively restrict where the cursor can be positioned. Similarly DefaultCaret will call into the NavigationFilter when the user is changing the selection to further restrict where the cursor can be positioned.

Subclasses can conditionally call into supers implementation to restrict where the cursor can be placed, or call directly into the FilterBypass.

Since:

1.4

See Also:

Caret, DefaultCaret, View

Nested Class Summary
static class	NavigationFilter.FilterBypass           Used as a way to circumvent calling back into the caret to position the cursor.

 

Constructor Summary
NavigationFilter()

 

Method Summary
int	getNextVisualPositionFrom(JTextComponent text, int pos, Position.Bias bias, int direction, Position.Bias[] biasRet)           Returns the next visual position to place the caret at from an existing position.
void	moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)           Invoked prior to the Caret moving the dot.
void	setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)           Invoked prior to the Caret setting the dot.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

NavigationFilter

public NavigationFilter()

setDot

public void setDot(NavigationFilter.FilterBypass fb,
                   int dot,
                   Position.Bias bias)

Invoked prior to the Caret setting the dot. The default implementation calls directly into the FilterBypass with the passed in arguments. Subclasses may wish to conditionally call super with a different location, or invoke the necessary method on the FilterBypass

Parameters:

fb - FilterBypass that can be used to mutate caret position

dot - the position >= 0

bias - Bias to place the dot at

moveDot

public void moveDot(NavigationFilter.FilterBypass fb,
                    int dot,
                    Position.Bias bias)

Invoked prior to the Caret moving the dot. The default implementation calls directly into the FilterBypass with the passed in arguments. Subclasses may wish to conditionally call super with a different location, or invoke the necessary methods on the FilterBypass.

Parameters:

fb - FilterBypass that can be used to mutate caret position

dot - the position >= 0

bias - Bias for new location

getNextVisualPositionFrom

public int getNextVisualPositionFrom(JTextComponent text,
                                     int pos,
                                     Position.Bias bias,
                                     int direction,
                                     Position.Bias[] biasRet)
                              throws BadLocationException

Returns the next visual position to place the caret at from an existing position. The default implementation simply forwards the method to the root View. Subclasses may wish to further restrict the location based on additional criteria.

Parameters:

text - JTextComponent containing text

pos - Position used in determining next position

bias - Bias used in determining next position

direction - the direction from the current position that can be thought of as the arrow keys typically found on a keyboard. This will be one of the following values:

• SwingConstants.WEST
• SwingConstants.EAST
• SwingConstants.NORTH
• SwingConstants.SOUTH

biasRet - Used to return resulting Bias of next position

Returns:

the location within the model that best represents the next location visual position

Throws:

BadLocationException

IllegalArgumentException - if direction doesn't have one of the legal values above