edu.hws.jcm.draw

Class Panner

java.lang.Object

edu.hws.jcm.draw.Drawable

edu.hws.jcm.draw.Panner

All Implemented Interfaces:

MouseListener, MouseMotionListener, Serializable, EventListener

public class Panner
extends Drawable
implements MouseListener, MouseMotionListener

When a Panner object is added to a CoordinateRect, it becomes possible to "grab" the coordinate rectangle and pan it (that is, slide it around by moving it with the mouse). By default, the user must right-click-and-drag to pan the coordinates, but this can be changed by providing an argument to the constructor. It is possible to set a Controller to be notified each time the mouse moves while the user is dragging. Alternatively, or in addition, you can set a Controller to be notified when the user finishes dragging. However, for the most part this is unnecessary, since the Drawables in the CoordinateRect will for the most part redraw themselves properly when the limits on the CoordinateRect change. However, if you have Computable objects that depend on the coordinate limits, then they will need to be recomputed. (This will be the case if you use value objects returned by the getValueObject() method in the CoordinateRect class.)

A Panner, p, is inactive if its "visible" property has been set to false. (This is done by calling p.setVisible(false).)

See Also:

Serialized Form

Field Summary

Fields inherited from class edu.hws.jcm.draw.Drawable

canvas, coords

Constructor Summary

Constructors

Constructor and Description
Panner() Create a Panner object that will let the user pan the CoordinateRect that contains the Panner by right-clicking and dragging (or, on Macintosh, command-clicking).
Panner(int modifierSet) Create a Panner object that will let the user click-and-drag to pan the CoordinateRect that contains the Panner.

Method Summary

Modifier and Type	Method and Description
void	draw(Graphics g, boolean coordsChanged) Override the abstract draw() method from the Drawable class.
Controller	getOnFinishDrag() Get the Controller that is notified when the user finishs a drag.
Controller	getOnUserAction() Get the Controller that is notified when the user moves the mouse during a drag.
void	mouseClicked(MouseEvent evt) Responds to a mouse-click.
void	mouseDragged(MouseEvent evt) Responds to a mouse-drag.
void	mouseEntered(MouseEvent evt) Responds to a mouse-enter event.
void	mouseExited(MouseEvent evt) Responds to a mouse-exit event.
void	mouseMoved(MouseEvent evt) Responds when mouse moves.
void	mousePressed(MouseEvent evt) Responds to a mouse-press.
void	mouseReleased(MouseEvent evt) Responds to a mouse-release.
void	setOnFinishDrag(Controller c) Set a Controller that will be notified (by calling its compute method) whenever the user finishes a drag operation.
void	setOnUserAction(Controller c) Set a Controller that will be notified (by calling its compute method) whenever the user moves the mouse during a drag.
protected void	setOwnerData(DisplayCanvas canvas, CoordinateRect coords) Called when this object is added to a DisplayCanvas.

Methods inherited from class edu.hws.jcm.draw.Drawable

getVisible, needsRedraw, setVisible

Methods inherited from class java.lang.Object

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

Constructor Detail

Panner

public Panner()

Create a Panner object that will let the user pan the CoordinateRect that contains the Panner by right-clicking and dragging (or, on Macintosh, command-clicking).

Panner

public Panner(int modifierSet)

Create a Panner object that will let the user click-and-drag to pan the CoordinateRect that contains the Panner. The mouse-pressed event must have the specfied set of modifiers set.

Parameters:

modifiers - If the value is zero, the user drags the CoordinateRect by clicking without pressing any modifier keys. Otherwise, the value should be a combination of one or more of the constants MouseEvent.SHIFT_MASK, MouseEvent.CTRL_MASK, MouseEvent.META_MASK, and MouseEvent.ALT_MASK, or'ed together. (Remember that right-clicking sets META_MASK and clicking with a middle mouse button sets ALT_MASK.)

Method Detail

setOnUserAction

public void setOnUserAction(Controller c)

Set a Controller that will be notified (by calling its compute method) whenever the user moves the mouse during a drag. If the value is null, no Controller is notified. Note that Drawables generally redraw themselvs correctly during the drag anyway, without any Controller being involved. Even if there are other things that need to be computed, it's probably better to compute them only once at the end of the drag. Do this by calling setOnFinishDrag() instead of this method.

getOnUserAction

public Controller getOnUserAction()

Get the Controller that is notified when the user moves the mouse during a drag. Returns null if no Controller is notified.

setOnFinishDrag

public void setOnFinishDrag(Controller c)

Set a Controller that will be notified (by calling its compute method) whenever the user finishes a drag operation. If the value is null, no Controller is notified. You only need to do this if you have to recompute some object that depends on the coordinate limits of the CoordinateRect that contains this Panner object. Presumably, this will be an object that depends on one if the Value objects returned by the getValueObject() method in the CoordinatRect class.

getOnFinishDrag

public Controller getOnFinishDrag()

Get the Controller that is notified when the user finishs a drag. Returns null if no Controller is notified.

setOwnerData

protected void setOwnerData(DisplayCanvas canvas,
                            CoordinateRect coords)

Called when this object is added to a DisplayCanvas. Not meant to be called directly.

Overrides:

setOwnerData in class Drawable

draw

public void draw(Graphics g,
                 boolean coordsChanged)

Override the abstract draw() method from the Drawable class. This is defined to be empty since a Panner object has no visible representation.

Specified by:

draw in class Drawable

Parameters:

g - The graphics context in which the Drawble is to be drawn. (The drawing can change the color in g, but should not permanently change font, painting mode, etc. Thus, every drawable is responsible for setting the color it wants to use.)

coordsChanged - Indicates whether the CoordinateRect has changed.

mousePressed

public void mousePressed(MouseEvent evt)

Responds to a mouse-press. Not meant to be called directly.

Specified by:

mousePressed in interface MouseListener

mouseDragged

public void mouseDragged(MouseEvent evt)

Responds to a mouse-drag. Not meant to be called directly.

Specified by:

mouseDragged in interface MouseMotionListener

mouseReleased

public void mouseReleased(MouseEvent evt)

Responds to a mouse-release. Not meant to be called directly.

Specified by:

mouseReleased in interface MouseListener

mouseClicked

public void mouseClicked(MouseEvent evt)

Responds to a mouse-click. Not meant to be called directly. Defined to be empty in this class.

Specified by:

mouseClicked in interface MouseListener

mouseMoved

public void mouseMoved(MouseEvent evt)

Responds when mouse moves. Not meant to be called directly. Defined to be empty in this class.

Specified by:

mouseMoved in interface MouseMotionListener

mouseEntered

public void mouseEntered(MouseEvent evt)

Responds to a mouse-enter event. Not meant to be called directly. Defined to be empty in this class.

Specified by:

mouseEntered in interface MouseListener

mouseExited

public void mouseExited(MouseEvent evt)

Responds to a mouse-exit event. Not meant to be called directly. Defined to be empty in this class.

Specified by:

mouseExited in interface MouseListener