draw.controller.handler

Class Handler

java.lang.Object

draw.controller.handler.Handler

All Implemented Interfaces:

IActionInterface

Direct Known Subclasses:

ChangeCursorHandler, CreateHandler, ResizeHandler, SelectHandler

public abstract class Handler
extends java.lang.Object
implements IActionInterface

Handler for Chain of Responsibilities. This class provides a default terminal implementation, that is, invocations on any of the methods in IActionInterface are ignored, and false is returned.

Field Summary

Fields inherited from interface draw.controller.IActionInterface

NoAnchor, NorthEastAnchor, NorthWestAnchor, SouthEastAnchor, SouthWestAnchor

Constructor Summary

Constructors

Constructor and Description
Handler(Model model, DrawingPalette view)

Method Summary

Modifier and Type	Method and Description
boolean	complete(java.awt.Point pt, int modifiers, java.util.Optional<Element> elt) Complete the mouse interaction.
boolean	completeAnchor(java.awt.Point pt, int modifiers, Element elt) Complete the mouse interaction as started by dragType.
boolean	drag(java.awt.Point start, int modifiers, java.util.Optional<Element> elt, java.awt.Point current) Act on the mouse drag.
boolean	dragAnchor(java.awt.Point start, int modifiers, Element elt, java.awt.Point current) Act on the anchor with mouse down.
java.util.Optional<Handler>	getNext() Return next one in chain, to allow external configuration.
boolean	isInterested() Uses currently selected action to determine if this handler is interested in processing events.
boolean	move(java.awt.Point pt, int modifiers, java.util.Optional<Element> elt, int anchor) Movement of cursor detected without the mouse button being pressed.
void	paint(java.awt.Graphics g) Each handler gets the chance to override and provide specific paint capabilities after elements are drawn.
Handler	setNext(Handler next) Add next to be the next in the chain.
boolean	start(java.awt.Point pt, int modifiers, java.util.Optional<Element> elt) Initiate action by pressing mouse at point with, potentially, a selected element.
boolean	startAnchor(java.awt.Point pt, int modifiers, Element elt, int anchor) Start the mouse interaction as started by dragType.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Handler

public Handler(Model model,
               DrawingPalette view)

Method Detail

getNext

public java.util.Optional<Handler> getNext()

Return next one in chain, to allow external configuration.

Returns:

Return next one in the chain.

isInterested

public boolean isInterested()

Uses currently selected action to determine if this handler is interested in processing events. Each handler subclass overrides the interested(Action) method to declare actions of interest.

Returns:

whether a given handler is interested in processing events

setNext

public Handler setNext(Handler next)

Add next to be the next in the chain. In draw.2, fixed to return next instead of self to chain properly.

Parameters:

next - Next handler to append

Returns:

next, so programmer can chain together

move

public boolean move(java.awt.Point pt,
                    int modifiers,
                    java.util.Optional<Element> elt,
                    int anchor)

Description copied from interface: IActionInterface

Movement of cursor detected without the mouse button being pressed.

Element is the optional element over which the point is moving. If it is present then there are two options:

1. anchor is one of these values, as it passes over the anchor area.
   • Cursor.NW_RESIZE_CURSOR (6)
   • Cursor.NE_RESIZE_CURSOR (7)
   • Cursor.SE_RESIZE_CURSOR (5)
   • Cursor.SW_RESIZE_CURSOR (4)
2. anchor is zero (0 or NoAnchor) which means it points over an element.

When element is not present, then cursor is moving over some place in which no element intersects.

In all cases, modifiers reflects whether shift or control is down.

Specified by:

move in interface IActionInterface

Parameters:

pt - mouse location

modifiers - keyboard modifiers in effect

elt - optional element in play

anchor - which anchor is affected

Returns:

whether mouse action was processed

start

public boolean start(java.awt.Point pt,
                     int modifiers,
                     java.util.Optional<Element> elt)

Description copied from interface: IActionInterface

Initiate action by pressing mouse at point with, potentially, a selected element.

Specified by:

start in interface IActionInterface

Parameters:

pt - starting an element action at this mouse location

modifiers - keyboard modifiers in effect

elt - optional element in play

Returns:

whether mouse action was processed

drag

public boolean drag(java.awt.Point start,
                    int modifiers,
                    java.util.Optional<Element> elt,
                    java.awt.Point current)

Description copied from interface: IActionInterface

Act on the mouse drag. Pass along modifiers (SHIFT, CONTROL, etc...).

Specified by:

drag in interface IActionInterface

Parameters:

start - original starting mouse location of this drag action

modifiers - keyboard modifiers in effect

elt - optional element in play

current - current mouse location

Returns:

whether mouse action was processed

complete

public boolean complete(java.awt.Point pt,
                        int modifiers,
                        java.util.Optional<Element> elt)

Description copied from interface: IActionInterface

Complete the mouse interaction.

Specified by:

complete in interface IActionInterface

Parameters:

pt - ending mouse location of this mouse action

modifiers - keyboard modifiers in effect

elt - optional element in play

Returns:

whether mouse action was processed

startAnchor

public boolean startAnchor(java.awt.Point pt,
                           int modifiers,
                           Element elt,
                           int anchor)

Description copied from interface: IActionInterface

Start the mouse interaction as started by dragType.

Specified by:

startAnchor in interface IActionInterface

Parameters:

pt - start an anchor at this mouse location

modifiers - keyboard modifiers in effect

elt - affected element

anchor - initiating anchor index position

Returns:

whether mouse action was processed

dragAnchor

public boolean dragAnchor(java.awt.Point start,
                          int modifiers,
                          Element elt,
                          java.awt.Point current)

Description copied from interface: IActionInterface

Act on the anchor with mouse down. Pass along modifiers (SHIFT, CONTROL, etc...)

Specified by:

dragAnchor in interface IActionInterface

Parameters:

start - mouse location where action started

modifiers - keyboard modifiers in effect

elt - affected element

current - current mouse location

Returns:

whether mouse action was processed

completeAnchor

public boolean completeAnchor(java.awt.Point pt,
                              int modifiers,
                              Element elt)

Description copied from interface: IActionInterface

Complete the mouse interaction as started by dragType.

Specified by:

completeAnchor in interface IActionInterface

Parameters:

pt - ending an anchor action at this mouse location

modifiers - keyboard modifiers in effect

elt - affected element

Returns:

whether mouse action was processed

paint

public void paint(java.awt.Graphics g)

Each handler gets the chance to override and provide specific paint capabilities after elements are drawn.

Specified by:

paint in interface IActionInterface

Parameters:

g - Graphics context into which to draw whatever is necessary based on the tool