Package edu.cnu.mdi.item

Class ConnectorItem

java.lang.Object

edu.cnu.mdi.item.AItem

edu.cnu.mdi.item.PathBasedItem

edu.cnu.mdi.item.PolylineItem

edu.cnu.mdi.item.ConnectorItem

All Implemented Interfaces:

IFeedbackProvider, IDrawable, EventListener

public class ConnectorItem
extends PolylineItem

A connection between two connectable items, drawn as an open polyline with an editable elbow.

Geometry model

• Vertex 0 — anchored to startItem.
• Vertex 1 — elbow (user-draggable).
• Vertex 2 — anchored to endItem.

Endpoints are recomputed from the connected items each time the connector's geometry needs to be validated, so the connection follows its endpoints when nodes move. The elbow vertex is preserved across anchor sync operations.

Anchor synchronisation

The connector compares the current endpoint world positions against the last-known anchor positions (lastStart and lastEnd) before redrawing. Synchronisation is skipped when the anchors have not moved, preventing the connector from being perpetually marked dirty on every frame.

Field Summary

Fields inherited from class edu.cnu.mdi.item.AItem

_connectable, _deletable, _dirty, _displayName, _doubleClickable, _draggable, _enabled, _focus, _FOCUSFILL, _lastDrawnPolygon, _layer, _line, _locked, _modification, _path, _popupMenu, _resizable, _resizePolicy, _rightClickable, _rotatable, _selectable, _selected, _style, _styleEditable, _visible, rotateIcon, RPSIZE, RPSIZE2, SPSIZE, SPSIZE2

Constructor Summary

Constructors

Constructor	Description
ConnectorItem(Layer layer, AItem startItem, AItem endItem)	Create a connector with a single elbow between two items.

Method Summary

Modifier and Type	Method	Description
void	drawItem(Graphics2D g2, IContainer container)	Custom drawer for the item.
AItem	getEndItem()	Return the item this connector terminates at.
AItem	getStartItem()	Return the item this connector originates from.
Rectangle2D.Double	getWorldBounds()	Get the world bounding rectangle of the item.
void	modify()	A modification such as a drag, resize or rotate is continuing.
boolean	shouldDraw(Graphics2D g2, IContainer container)	Checks whether the item should be drawn.

Methods inherited from class edu.cnu.mdi.item.PolylineItem

reshape

Methods inherited from class edu.cnu.mdi.item.PathBasedItem

contains, getBounds, getRotatePoint, rotate, scale, singlePointBounds, threePointAngle, translateWorld, updateFocus

Methods inherited from class edu.cnu.mdi.item.AItem

acceptModification, applyGeometryProperties, applyProperties, applyStyleProperties, createPopupMenu, doubleClicked, draw, drawSelections, enclosed, equals, focusFill, geometryChanged, getAzimuth, getContainer, getDisplayName, getFeedbackStrings, getFocus, getFocusPoint, getItemModification, getLastDrawnPolygon, getLayer, getLine, getPath, getPopupMenu, getResizePolicy, getSelectionPoints, getStyle, getStyleSafe, getView, hashCode, inASelectRect, inRotatePoint, inSelectPoint, isConnectable, isDeletable, isDirty, isDoubleClickable, isDraggable, isEnabled, isLocked, isResizable, isRightClickable, isRotatable, isSelectable, isSelected, isStyleEditable, isTrackable, isVisible, modificationRejected, prepareForPopup, prepareForRemoval, setAzimuth, setConnectable, setDeletable, setDirty, setDisplayName, setDoubleClickable, setDraggable, setEnabled, setFillFocus, setFocus, setLocked, setModification, setResizable, setResizePolicy, setRightClickable, setRotatable, setSelectable, setSelected, setStyle, setStyleEditable, setVisible, startModification, stopModification, translateLocal

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface edu.cnu.mdi.graphics.drawable.IDrawable

getName

Constructor Details

ConnectorItem

public ConnectorItem(Layer layer,
 AItem startItem,
 AItem endItem)

Create a connector with a single elbow between two items.

The initial geometry is an L-shape: start anchor → elbow at (startAnchor.x, endAnchor.y) → end anchor.

Parameters:

layer - the layer to add the connector to; recommended to use a connection layer drawn below node layers

startItem - the item the connector originates from; must not be null

endItem - the item the connector terminates at; must not be null

Throws:

NullPointerException - if either item argument is null

Method Details

shouldDraw

public boolean shouldDraw(Graphics2D g2,
 IContainer container)

Checks whether the item should be drawn. This is an additional check, beyond the simple visibility flag check. For example, it might check whether the item intersects the area being drawn.

Recomputes endpoint anchors before drawing if either endpoint item has moved since the last draw. Only performs the sync (and marks the item dirty) when a change is detected, avoiding a perpetual dirty-every-frame cycle.

Overrides:

shouldDraw in class PathBasedItem

Parameters:

g2 - the graphics context.

container - the graphical container being rendered.

Returns:

true if the item passes any and all tests, and should be drawn.

drawItem

public void drawItem(Graphics2D g2,
 IContainer container)

Custom drawer for the item.

Syncs anchors if needed, then delegates to PolylineItem.

Overrides:

drawItem in class PolylineItem

Parameters:

g2 - the graphics context.

container - the graphical container being rendered.

modify

public void modify()

A modification such as a drag, resize or rotate is continuing.

Lets PolylineItem reshape the elbow vertex, then forces endpoints back onto their anchored items so the connection cannot be accidentally detached by dragging a handle.

Overrides:

modify in class PathBasedItem

getWorldBounds

public Rectangle2D.Double getWorldBounds()

Get the world bounding rectangle of the item.

Ensures anchors are current before bounds queries are used for picking and visibility tests.

Overrides:

getWorldBounds in class PathBasedItem

Returns:

the world box containing the item.

getStartItem

public AItem getStartItem()

Return the item this connector originates from.

Returns:

the start item; never null

getEndItem

public AItem getEndItem()

Return the item this connector terminates at.

Returns:

the end item; never null