Package edu.cnu.mdi.view

Class HeadlessPointerTool

java.lang.Object

edu.cnu.mdi.view.HeadlessPointerTool

All Implemented Interfaces:

MouseListener, MouseMotionListener, EventListener

public class HeadlessPointerTool
extends Object
implements MouseListener, MouseMotionListener

A minimal, "headless" pointer tool that enables item dragging (and other item modifications supported by AItem) on views that do not have a visible AToolBar.

In the toolbar-driven workflow, a pointer tool (e.g. PointerButton) is typically responsible for installing mouse listeners and driving AItem modification state (start/modify/stop). This class provides the same essential behavior without requiring a toolbar UI.

Behavior

• On mouse press, hit-tests for an AItem.
• If the item is draggable, the tool arms a potential drag.
• Once the mouse has moved beyond a configurable pixel threshold, the tool creates an ItemModification, calls AItem.startModification(), and then repeatedly calls AItem.modify() as the mouse moves.
• On mouse release, if a modification was started, the tool calls AItem.stopModification().

This tool intentionally does not attempt to manage selection state or multi-item operations; it is meant for "mini-map"/virtual views such as VirtualView, where the primary goal is simple item dragging.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_DRAG_THRESHOLD_PX	Default drag threshold (pixels) before promoting a press into a drag.

Constructor Summary

Constructors

Constructor	Description
HeadlessPointerTool(BaseView view)	Create and immediately install a headless pointer tool on the view's canvas.

Method Summary

Modifier and Type	Method	Description
void	dispose()	Remove listeners from the component.
int	getDragThresholdPx()
void	mouseClicked(MouseEvent e)
void	mouseDragged(MouseEvent e)
void	mouseEntered(MouseEvent e)
void	mouseExited(MouseEvent e)
void	mouseMoved(MouseEvent e)
void	mousePressed(MouseEvent e)
void	mouseReleased(MouseEvent e)
void	setDragThresholdPx(int px)	Set the drag threshold in pixels used to promote a press into a drag.

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_DRAG_THRESHOLD_PX

public static final int DEFAULT_DRAG_THRESHOLD_PX

Default drag threshold (pixels) before promoting a press into a drag.

See Also:

• Constant Field Values

Constructor Details

HeadlessPointerTool

public HeadlessPointerTool(BaseView view)

Create and immediately install a headless pointer tool on the view's canvas.

Parameters:

view - the view whose container/canvas should receive pointer behavior.

Throws:

NullPointerException - if view, its container, or its component is null.

Method Details

dispose

public void dispose()

Remove listeners from the component. Call this if the view/canvas is being disposed or replaced, to avoid leaks and duplicate listeners.

setDragThresholdPx

public void setDragThresholdPx(int px)

Set the drag threshold in pixels used to promote a press into a drag.

Parameters:

px - threshold in pixels; values less than 0 are treated as 0.

getDragThresholdPx

public int getDragThresholdPx()

Returns:

current drag threshold in pixels.

mousePressed

public void mousePressed(MouseEvent e)

Specified by:

mousePressed in interface MouseListener

mouseReleased

public void mouseReleased(MouseEvent e)

Specified by:

mouseReleased in interface MouseListener

mouseClicked

public void mouseClicked(MouseEvent e)

Specified by:

mouseClicked in interface MouseListener

mouseEntered

public void mouseEntered(MouseEvent e)

Specified by:

mouseEntered in interface MouseListener

mouseExited

public void mouseExited(MouseEvent e)

Specified by:

mouseExited in interface MouseListener

mouseDragged

public void mouseDragged(MouseEvent e)

Specified by:

mouseDragged in interface MouseMotionListener

mouseMoved

public void mouseMoved(MouseEvent e)

Specified by:

mouseMoved in interface MouseMotionListener