org.jhotdraw.draw

Interface Constrainer

All Known Implementing Classes:

AbstractConstrainer, GridConstrainer

public interface Constrainer

A constrainer constrains editing operations performed by Tools and Handles on a DrawingView.

Constrainer objects are associated to DrawingView's.

Constrainers can draw themselves onto the drawing view to visualize the constraints that they impose. Typically by drawing a grid of some kind.

Design Patterns

Strategy
Editing can be constrained by a constrainer which is associated to a drawing view.
Context: DrawingView; Strategy: Constrainer.

Method Summary

Modifier and Type	Method and Description
void	addChangeListener(javax.swing.event.ChangeListener listener) Adds a change listener.
double	constrainAngle(double angle) Constrains the given angle (in radians).
java.awt.geom.Point2D.Double	constrainPoint(java.awt.geom.Point2D.Double p) Constrains the placement of a point towards the closest constraint in any direction.
java.awt.geom.Rectangle2D.Double	constrainRectangle(java.awt.geom.Rectangle2D.Double r) Constrains the placement of a rectangle towards the closest constrainment in any direction.
void	draw(java.awt.Graphics2D g, DrawingView view) Draws the constrainer grid for the specified drawing view.
void	removeChangeListener(javax.swing.event.ChangeListener listener) Removes a change listener.
double	rotateAngle(double angle, RotationDirection dir) Moves the given angle (in radians) to the closest constrained orientation in the specified direction.
java.awt.geom.Point2D.Double	translatePoint(java.awt.geom.Point2D.Double p, TranslationDirection dir) Moves a point to the closest constrained location in the specified direction.
java.awt.geom.Rectangle2D.Double	translateRectangle(java.awt.geom.Rectangle2D.Double r, TranslationDirection dir) Moves a rectangle to the closest constrained location in the specified direction.

Method Detail

constrainPoint

java.awt.geom.Point2D.Double constrainPoint(java.awt.geom.Point2D.Double p)

Constrains the placement of a point towards the closest constraint in any direction.

This method changes the point which is passed as a parameter.

Parameters:

p - A point on the drawing.

Returns:

Returns the constrained point.

translatePoint

java.awt.geom.Point2D.Double translatePoint(java.awt.geom.Point2D.Double p,
                                            TranslationDirection dir)

Moves a point to the closest constrained location in the specified direction.

This method changes the point which is passed as a parameter.

Parameters:

p - A point on the drawing.

dir - A direction.

Returns:

Returns the constrained point.

constrainRectangle

java.awt.geom.Rectangle2D.Double constrainRectangle(java.awt.geom.Rectangle2D.Double r)

Constrains the placement of a rectangle towards the closest constrainment in any direction.

This method changes the location of the rectangle which is passed as a parameter. This method does not change the size of the rectangle.

Parameters:

r - A rectangle on the drawing.

Returns:

Returns the constrained rectangle.

translateRectangle

java.awt.geom.Rectangle2D.Double translateRectangle(java.awt.geom.Rectangle2D.Double r,
                                                    TranslationDirection dir)

Moves a rectangle to the closest constrained location in the specified direction.

This method changes the location of the rectangle which is passed as a parameter. This method only performs a translation - it does not change the size of the rectangle.

Parameters:

r - A rectangle on the drawing.

dir - A direction.

Returns:

Returns the constrained rectangle.

constrainAngle

double constrainAngle(double angle)

Constrains the given angle (in radians). This method changes the angle which is passed as a parameter.

Parameters:

angle - The angle (in radians).

Returns:

The closest constrained angle (in radians).

rotateAngle

double rotateAngle(double angle,
                   RotationDirection dir)

Moves the given angle (in radians) to the closest constrained orientation in the specified direction.

Parameters:

angle - The angle (in radians).

Returns:

The closest constrained angle (in radians) in the specified direction.

draw

void draw(java.awt.Graphics2D g,
          DrawingView view)

Draws the constrainer grid for the specified drawing view.

addChangeListener

void addChangeListener(javax.swing.event.ChangeListener listener)

Adds a change listener.

removeChangeListener

void removeChangeListener(javax.swing.event.ChangeListener listener)

Removes a change listener.