jfig.commands
Class Command

java.lang.Object
  jfig.commands.Command

Direct Known Subclasses:

AlignObjectsCommand, BreakCompoundCommand, ConvertObjectCommand, CopyObjectCommand, CopyToClipboardCommand, CreateArcCommand, CreateBezierCommand, CreateBulletCommand, CreateCircleCommand, CreateClosedBezierCommand, CreateClosedSplineCommand, CreateCompoundCommand, CreateDimensioningCommand, CreateEllipseCommand, CreateFreehandCommand, CreateImageCommand, CreatePolygonCommand, CreatePolylineCommand, CreateRectangleCommand, CreateRoundedRectangleCommand, CreateSplineCommand, CreateTextCommand, CreateTriggerCommand, CutPointCommand, CutToClipboardCommand, DeleteObjectCommand, EditCommentCommand, EditObjectCommand, InsertPointCommand, JCreateImageCommand, JEditObjectCommand, JoinSplitLinesCommand, JOpenCompoundCommand, MirrorXCommand, MirrorYCommand, MoveObjectCommand, MovePointCommand, OpenCompoundCommand, PasteFromClipboardCommand, ResizeTextCommand, RotateObjectCommand, ScaleObjectCommand, SelectLibraryObjectCommand, SnapToGridCommand, UpdateCommand, ZoomRegionCommand

public class Command

extends java.lang.Object

the empty, do-nothing, jfig editing command.

Command: To avoid a single, monolithic editor architecture, all editing functionality of the jfig graphics editor is provided by small, standalone editor 'command' objects, organized into a class hierarchy of command classes in package jfig.commands. This class, Command, is the base class of all these command classes and models an empty, do-nothing, all-time-ready, command.

Field Summary

protected FigBasicEditor	editor
protected FigCanvas	objectCanvas
protected boolean	ready

Constructor Summary

Command(FigBasicEditor editor, FigCanvas objectCanvas)
create an empty (idle, do-nothing) Command object

Method Summary

void	cancel() cancel the current editor command
void	execute() execute the current editor command
java.lang.String	getDescription() one-line description of this command
FigObject[]	getModifiedObjects() return an array of all objects modified by this Command.
boolean	isReady() check whether this command is completed/ready, or not
void	message(java.lang.String msg) print a (possibly long) message
void	mousePressed(FigCanvasEvent evt) react to a mouse click on the editor canvas
void	notifyEditor() provide a callback from commands to their editor.
void	statusMessage(java.lang.String msg) print a status message, typically a short one-line message
java.lang.String	toString() return a (possibly verbose) description of this Command object
void	undo() undo this command

Methods inherited from class java.lang.Object

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

Field Detail

objectCanvas

protected FigCanvas objectCanvas

editor

protected FigBasicEditor editor

ready

protected boolean ready

Constructor Detail

Command

public Command(FigBasicEditor editor,
               FigCanvas objectCanvas)

create an empty (idle, do-nothing) Command object

A new idle Command for 'editor', display on 'objectCanvas'. Note that the idle Command is always ready.

Method Detail

cancel

public void cancel()

cancel the current editor command

cancel and cleanup the current command. Note that this method is empty for class Command, but might be implemented by subclasses.

execute

public void execute()

execute the current editor command

This method is empty for class Command.

undo

public void undo()

undo this command

Try to undo this command as far as possible. Don't try to undo() a command that has never been execute()d before. This method is empty for class Command.

mousePressed

public void mousePressed(FigCanvasEvent evt)

react to a mouse click on the editor canvas

This method provides the central callback from the editor to its current command object. Passing a FigCanvasEvent parameter, the editor provides information both about the screen coordinates and the world coordinates of the mouse event.

Naturally, mouse presses are ignored for class Command.

isReady

public boolean isReady()

check whether this command is completed/ready, or not

notifyEditor

public void notifyEditor()

provide a callback from commands to their editor.

This method serves as a callback from command objects to their editor. Because each command object is used for one single and atomic editing operation only, the editor has to create a new command once the previous command has execute()d. This is achieved by calling notifyEditor() from within a command, once the command has executed and is ready. The typical use is to implement the xfig-style editor modes, e.g. to create a new CopyCommand directly after the previous CopyCommand has finished.

getModifiedObjects

public FigObject[] getModifiedObjects()

return an array of all objects modified by this Command. This may return null or an array of length null.

statusMessage

public void statusMessage(java.lang.String msg)

print a status message, typically a short one-line message

message

public void message(java.lang.String msg)

print a (possibly long) message

getDescription

public java.lang.String getDescription()

one-line description of this command

return a one-line desription of this command, e.g. to label the undo/redo buttons, if any

toString

public java.lang.String toString()

return a (possibly verbose) description of this Command object