org.opensourcephysics.display
Class DrawingFrame

java.lang.Object
  java.awt.Component
      java.awt.Container
          java.awt.Window
              java.awt.Frame
                  javax.swing.JFrame
                      org.opensourcephysics.display.OSPFrame
                          org.opensourcephysics.display.DrawingFrame

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.datatransfer.ClipboardOwner, java.awt.image.ImageObserver, java.awt.MenuContainer, java.awt.print.Printable, javax.swing.RootPaneContainer, java.io.Serializable, javax.swing.WindowConstants

Direct Known Subclasses:

Complex2DFrame, ComplexPlotFrame, DisplayFrame, FFT2DFrame, FFTFrame, HistogramFrame, LatticeFrame, ParticleFrame, PlotFrame, RasterFrame, Scalar2DFrame, Vector2DFrame

public class DrawingFrame

extends OSPFrame

implements java.awt.datatransfer.ClipboardOwner

Drawing Frame: a frame that contains a drawing panel.

See Also:

Serialized Form

Nested Class Summary

protected static class

DrawingFrame.DrawingFrameLoader

Nested classes inherited from class javax.swing.JFrame

javax.swing.JFrame.AccessibleJFrame

Nested classes inherited from class java.awt.Frame

java.awt.Frame.AccessibleAWTFrame

Nested classes inherited from class java.awt.Window

java.awt.Window.AccessibleAWTWindow

Nested classes inherited from class java.awt.Container

java.awt.Container.AccessibleAWTContainer

Nested classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy

Field Summary

protected javax.swing.JMenuItem	copyItem
protected java.awt.Window	customInspector
protected DrawingPanel	drawingPanel
protected javax.swing.JMenu	editMenu
protected javax.swing.JMenu	fileMenu
protected static int	MENU_SHORTCUT_KEY_MASK
protected javax.swing.JMenuItem	pasteItem
protected javax.swing.JMenuItem	replaceItem
protected Tool	reply

Fields inherited from class org.opensourcephysics.display.OSPFrame

animated, applet, appletMode, authorMode, autoclear, buttonPanel, chooserDir, constructorThreadGroup, customButtons, DEFAULT_LOOK_AND_FEEL, defaultLocales, keepHidden, launcherMode, osp_icon_file, strategy

Fields inherited from class javax.swing.JFrame

accessibleContext, EXIT_ON_CLOSE, rootPane, rootPaneCheckingEnabled

Fields inherited from class java.awt.Frame

CROSSHAIR_CURSOR, DEFAULT_CURSOR, E_RESIZE_CURSOR, HAND_CURSOR, ICONIFIED, MAXIMIZED_BOTH, MAXIMIZED_HORIZ, MAXIMIZED_VERT, MOVE_CURSOR, N_RESIZE_CURSOR, NE_RESIZE_CURSOR, NORMAL, NW_RESIZE_CURSOR, S_RESIZE_CURSOR, SE_RESIZE_CURSOR, SW_RESIZE_CURSOR, TEXT_CURSOR, W_RESIZE_CURSOR, WAIT_CURSOR

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.print.Printable

NO_SUCH_PAGE, PAGE_EXISTS

Fields inherited from interface javax.swing.WindowConstants

DISPOSE_ON_CLOSE, DO_NOTHING_ON_CLOSE, HIDE_ON_CLOSE

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

DrawingFrame()
DrawingFrame constructor that creates a default DrawingPanel.

DrawingFrame(DrawingPanel drawingPanel)
DrawingFrame constructor specifying the DrawingPanel that will be placed in the center of the content pane.

DrawingFrame(java.lang.String title, DrawingPanel _drawingPanel)
DrawingFrame constructor specifying the title and the DrawingPanel that will be placed in the center of the content pane.

Method Summary

void	addDrawable(Drawable drawable) Adds a drawable object to the frame's drawing panel.
void	clearDataAndRepaint() Clears data and repaints the drawing panel within this frame.
void	clearDrawables() Cleares drawable objects added by the user from this frame.
protected void	copyAction(XMLControlElement control) Copies objects found in the specified xml control.
org.opensourcephysics.display.axes.DrawableAxes	getAxes()
java.util.ArrayList	getDrawables() Gets Drawable previously objects added by the user.
java.util.ArrayList	getDrawables(java.lang.Class c) Gets Drawable objects added by the user of an assignable type.
DrawingPanel	getDrawingPanel() Gets the drawing panel.
static XML.ObjectLoader	getLoader() Returns an XML.ObjectLoader to save and load data for this program.
java.util.ArrayList	getObjectOfClass(java.lang.Class c) Gets objects of a specific class from the drawing panel.
void	inspectXML() Inspects the drawing frame by using an xml document tree.
void	invalidateImage() Invalidates image buffers if a drawing panel buffered.
boolean	isAutoscaleX() Determines if the panel's x axis autoscale property is true.
boolean	isAutoscaleY() Determines if the y axis autoscale property is true.
void	limitAutoscaleX(double floor, double ceil) Limits the xmin and xmax values during autoscaling so that the mininimum value will be no greater than the floor and the maximum value will be no smaller than the ceil.
void	limitAutoscaleY(double floor, double ceil) Limits ymin and ymax values during autoscaling so that the mininimum value will be no greater than the floor and the maximum value will be no smaller than the ceil.
protected javax.swing.JMenu	loadDisplayMenu() Adds a Display menu to the menu bar.
protected javax.swing.JMenu	loadToolsMenu() Adds a Tools menu to the menu bar.
void	lostOwnership(java.awt.datatransfer.Clipboard clipboard, java.awt.datatransfer.Transferable contents) Implementation of ClipboardOwner interface.
void	paint(java.awt.Graphics g) This is a hack to fix a bug when the reload button is pressed in browsers running JDK 1.4.
protected void	pasteAction(XMLControlElement control) Pastes drawables found in the specified xml control.
protected void	refreshGUI() Refreshes the user interface in response to display changes such as Language.
void	removeDrawable(Drawable drawable) Removes a drawable object to the frame's drawing panel.
void	removeObjectsOfClass(java.lang.Class c) Removes all objects of the given class from the drawable list.
void	render() Renders the drawing panel if the frame is showing and not iconified.
void	replaceAction(XMLControlElement control) Replaces the drawables with the drawables found in the specified XML control.
void	replaceDrawable(Drawable oldDrawable, Drawable newDrawable) Replaces a drawable object with another drawable.
void	saveXML()
void	setAutoscaleX(boolean autoscale) Autoscale the drawing panel's x axis using min and max values.
void	setAutoscaleY(boolean autoscale) Autoscale the y axis using min and max values.
void	setCartesian(java.lang.String xLabel, java.lang.String yLabel, java.lang.String plotTitle) Converts to cartesian coordinates.
void	setCustomInspector(java.awt.Window w) Sets a custom properties inspector window.
void	setDrawingPanel(DrawingPanel _drawingPanel) Adds the drawing panel to the the frame.
void	setEnabledCopy(boolean enable) Enables the copy edit menu item.
void	setEnabledPaste(boolean enable) Enables the paste edit menu item.
void	setEnabledReplace(boolean enable) Enables the replace edit menu item.
void	setInteractiveMouseHandler(InteractiveMouseHandler handler) Sets the interactive mouse handler if the drawing panel is an interactive panel.
void	setInteriorBackground(java.awt.Color color) Sets the interior background color for the current drawing panel.
void	setLogScale(boolean logX, boolean logY) Sets Cartesian axes to log scale.
void	setMessage(java.lang.String msg) Shows a message in a yellow text box in the lower right hand corner.
void	setMessage(java.lang.String msg, int location) Shows a message in a yellow text box at the given location.
void	setPixelsPerUnit(boolean enable, double xPixPerUnit, double yPixPerUnit) Sets the scale using pixels per unit.
void	setPolar(java.lang.String plotTitle, double deltaR) Converts to polar coordinates.
void	setPreferredMinMax(double xmin, double xmax, double ymin, double ymax) Sets the drawing panel's preferred scale.
void	setPreferredMinMaxX(double xmin, double xmax) Sets the drawing panel's preferred scale in the horizontal direction.
void	setPreferredMinMaxY(double ymin, double ymax) Sets the drawing panel's preferred scale in the vertical direction.
void	setSquareAspect(boolean isSquare) Sets the aspect ratio for horizontal to vertical to unity when true<\code>.
void	setXLabel(java.lang.String label) Sets the label for the X (horizontal) axis.
void	setYLabel(java.lang.String label) Sets the label for the Y (vertical) axis.

Methods inherited from class org.opensourcephysics.display.OSPFrame

addButton, bufferStrategyShow, clearData, createBufferStrategy, dispose, getChooser, getConstructorThreadGroup, getDefaultLocales, getMenu, isAnimated, isAuthorMode, isAutoclear, isIconified, isKeepHidden, isLauncherMode, parseXMLMenu, parseXMLMenu, print, removeMenu, removeMenuItem, setAnimated, setAuthorMode, setAutoclear, setDefaultCloseOperation, setFontLevel, setKeepHidden, setLauncherMode, setSize, setTitle, setVisible, show, wishesToExit

Methods inherited from class javax.swing.JFrame

addImpl, createRootPane, frameInit, getAccessibleContext, getContentPane, getDefaultCloseOperation, getGlassPane, getJMenuBar, getLayeredPane, getRootPane, isDefaultLookAndFeelDecorated, isRootPaneCheckingEnabled, paramString, processWindowEvent, remove, setContentPane, setDefaultLookAndFeelDecorated, setGlassPane, setJMenuBar, setLayeredPane, setLayout, setRootPane, setRootPaneCheckingEnabled, update

Methods inherited from class java.awt.Frame

addNotify, finalize, getCursorType, getExtendedState, getFrames, getIconImage, getMaximizedBounds, getMenuBar, getState, getTitle, isResizable, isUndecorated, remove, removeNotify, setCursor, setExtendedState, setIconImage, setMaximizedBounds, setMenuBar, setResizable, setState, setUndecorated

Methods inherited from class java.awt.Window

addPropertyChangeListener, addPropertyChangeListener, addWindowFocusListener, addWindowListener, addWindowStateListener, applyResourceBundle, applyResourceBundle, createBufferStrategy, createBufferStrategy, getBufferStrategy, getFocusableWindowState, getFocusCycleRootAncestor, getFocusOwner, getFocusTraversalKeys, getGraphicsConfiguration, getInputContext, getListeners, getLocale, getMostRecentFocusOwner, getOwnedWindows, getOwner, getToolkit, getWarningString, getWindowFocusListeners, getWindowListeners, getWindowStateListeners, hide, isActive, isFocusableWindow, isFocusCycleRoot, isFocused, isShowing, pack, postEvent, processEvent, processWindowFocusEvent, processWindowStateEvent, removeWindowFocusListener, removeWindowListener, removeWindowStateListener, setCursor, setFocusableWindowState, setFocusCycleRoot, setLocationRelativeTo, toBack, toFront

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getContainerListeners, getFocusTraversalPolicy, getInsets, getLayout, getMaximumSize, getMinimumSize, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, print, printComponents, processContainerEvent, remove, removeAll, removeContainerListener, setFocusTraversalKeys, setFocusTraversalPolicy, setFont, transferFocusBackward, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isOpaque, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, show, size, toString, transferFocus, transferFocusUpCycle

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.awt.MenuContainer

getFont, postEvent

Field Detail

fileMenu

protected javax.swing.JMenu fileMenu

editMenu

protected javax.swing.JMenu editMenu

copyItem

protected javax.swing.JMenuItem copyItem

pasteItem

protected javax.swing.JMenuItem pasteItem

replaceItem

protected javax.swing.JMenuItem replaceItem

drawingPanel

protected DrawingPanel drawingPanel

MENU_SHORTCUT_KEY_MASK

protected static final int MENU_SHORTCUT_KEY_MASK

customInspector

protected java.awt.Window customInspector

reply

protected Tool reply

Constructor Detail

DrawingFrame

public DrawingFrame()

DrawingFrame constructor that creates a default DrawingPanel. The default DrawingPanel is an InteractivePanel.

DrawingFrame

public DrawingFrame(DrawingPanel drawingPanel)

DrawingFrame constructor specifying the DrawingPanel that will be placed in the center of the content pane.

Parameters:

drawingPanel -

DrawingFrame

public DrawingFrame(java.lang.String title,
                    DrawingPanel _drawingPanel)

DrawingFrame constructor specifying the title and the DrawingPanel that will be placed in the center of the content pane.

Parameters:

title -

_drawingPanel -

Method Detail

render

public void render()

Renders the drawing panel if the frame is showing and not iconified.

Overrides:

render in class OSPFrame

invalidateImage

public void invalidateImage()

Invalidates image buffers if a drawing panel buffered.

Overrides:

invalidateImage in class OSPFrame

getDrawingPanel

public DrawingPanel getDrawingPanel()

Gets the drawing panel.

Returns:

the drawingPanel

setXLabel

public void setXLabel(java.lang.String label)

Sets the label for the X (horizontal) axis.

Parameters:

label - the label

setYLabel

public void setYLabel(java.lang.String label)

Sets the label for the Y (vertical) axis.

Parameters:

label - the label

setPolar

public void setPolar(java.lang.String plotTitle,
                     double deltaR)

Converts to polar coordinates.

Parameters:

plotTitle - String

deltaR - double

setCartesian

public void setCartesian(java.lang.String xLabel,
                         java.lang.String yLabel,
                         java.lang.String plotTitle)

Converts to cartesian coordinates.

Parameters:

xLabel - String

yLabel - String

plotTitle - String

limitAutoscaleX

public void limitAutoscaleX(double floor,
                            double ceil)

Limits the xmin and xmax values during autoscaling so that the mininimum value will be no greater than the floor and the maximum value will be no smaller than the ceil. Setting a floor or ceil value to Double.NaN<\code> will disable that limit.

Parameters:

floor - the xfloor value

ceil - the xceil value

limitAutoscaleY

public void limitAutoscaleY(double floor,
                            double ceil)

Limits ymin and ymax values during autoscaling so that the mininimum value will be no greater than the floor and the maximum value will be no smaller than the ceil. Setting a floor or ceil value to Double.NaN<\code> will disable that limit.

Parameters:

floor - the yfloor value

ceil - the yceil value

setAutoscaleX

public void setAutoscaleX(boolean autoscale)

Autoscale the drawing panel's x axis using min and max values. from measurable objects.

Parameters:

autoscale -

isAutoscaleX

public boolean isAutoscaleX()

Determines if the panel's x axis autoscale property is true.

Returns:

true<\code> if autoscaled.

setAutoscaleY

public void setAutoscaleY(boolean autoscale)

Autoscale the y axis using min and max values. from measurable objects.

Parameters:

autoscale -

isAutoscaleY

public boolean isAutoscaleY()

Determines if the y axis autoscale property is true.

Returns:

true<\code> if autoscaled.

setSquareAspect

public void setSquareAspect(boolean isSquare)

Sets the aspect ratio for horizontal to vertical to unity when true<\code>.

Parameters:

isSquare - boolean

setLogScale

public void setLogScale(boolean logX,
                        boolean logY)

Sets Cartesian axes to log scale.

Parameters:

logX -

logY -

setPixelsPerUnit

public void setPixelsPerUnit(boolean enable,
                             double xPixPerUnit,
                             double yPixPerUnit)

Sets the scale using pixels per unit.

Parameters:

enable - boolean enable fixed pixels per unit

xPixPerUnit - double

yPixPerUnit - double

setPreferredMinMax

public void setPreferredMinMax(double xmin,
                               double xmax,
                               double ymin,
                               double ymax)

Sets the drawing panel's preferred scale.

Parameters:

xmin -

xmax -

ymin -

ymax -

setPreferredMinMaxY

public void setPreferredMinMaxY(double ymin,
                                double ymax)

Sets the drawing panel's preferred scale in the vertical direction.

Parameters:

ymin -

ymax -

setPreferredMinMaxX

public void setPreferredMinMaxX(double xmin,
                                double xmax)

Sets the drawing panel's preferred scale in the horizontal direction.

Parameters:

xmin - the minimum value

xmax - the maximum value

clearDataAndRepaint

public void clearDataAndRepaint()

Clears data and repaints the drawing panel within this frame.

Overrides:

clearDataAndRepaint in class OSPFrame

clearDrawables

public void clearDrawables()

Cleares drawable objects added by the user from this frame.

addDrawable

public void addDrawable(Drawable drawable)

Adds a drawable object to the frame's drawing panel.

Parameters:

drawable -

replaceDrawable

public void replaceDrawable(Drawable oldDrawable,
                            Drawable newDrawable)

Replaces a drawable object with another drawable.

Parameters:

oldDrawable - Drawable

newDrawable - Drawable

removeDrawable

public void removeDrawable(Drawable drawable)

Removes a drawable object to the frame's drawing panel.

Parameters:

drawable -

setMessage

public void setMessage(java.lang.String msg)

Shows a message in a yellow text box in the lower right hand corner.

Parameters:

msg -

setMessage

public void setMessage(java.lang.String msg,
                       int location)

Shows a message in a yellow text box at the given location. location 0=bottom left location 1=bottom right location 2=top right location 3=top left

Parameters:

msg -

location -

getObjectOfClass

public java.util.ArrayList getObjectOfClass(java.lang.Class c)

Gets objects of a specific class from the drawing panel. Assignable subclasses are NOT returned. Interfaces CANNOT be specified. The same objects will be in the drawable list and the cloned list.

Parameters:

c - the class of the object

Returns:

the list

getDrawables

public java.util.ArrayList getDrawables()

Gets Drawable previously objects added by the user.

Returns:

the list

getAxes

public org.opensourcephysics.display.axes.DrawableAxes getAxes()

getDrawables

public java.util.ArrayList getDrawables(java.lang.Class c)

Gets Drawable objects added by the user of an assignable type. The list contains objects that are assignable from the class or interface.

Parameters:

c - the type of Drawable object

Returns:

the cloned list

See Also:

getObjectOfClass(Class c)

removeObjectsOfClass

public void removeObjectsOfClass(java.lang.Class c)

Removes all objects of the given class from the drawable list. Assignable subclasses are NOT removed. Interfaces CANNOT be specified.

Parameters:

c - the class

setInteractiveMouseHandler

public void setInteractiveMouseHandler(InteractiveMouseHandler handler)

Sets the interactive mouse handler if the drawing panel is an interactive panel. Throws an invalid cast exception if the panel is not of the correct type.

Parameters:

handler - the mouse handler

setDrawingPanel

public void setDrawingPanel(DrawingPanel _drawingPanel)

Adds the drawing panel to the the frame. The panel is added to the center of the frame's content pane.

Parameters:

_drawingPanel -

setInteriorBackground

public void setInteriorBackground(java.awt.Color color)

Sets the interior background color for the current drawing panel. The interior of a PlottingaPanel is the area inside the axes where is displayed. The interior of a DrawingPanel is the entire panel.

paint

public void paint(java.awt.Graphics g)

This is a hack to fix a bug when the reload button is pressed in browsers running JDK 1.4.

Parameters:

g -

setEnabledPaste

public void setEnabledPaste(boolean enable)

Enables the paste edit menu item.

Parameters:

enable - boolean

pasteAction

protected void pasteAction(XMLControlElement control)

Pastes drawables found in the specified xml control.

Parameters:

control - the xml control

setEnabledReplace

public void setEnabledReplace(boolean enable)

Enables the replace edit menu item.

Parameters:

enable - boolean

replaceAction

public void replaceAction(XMLControlElement control)

Replaces the drawables with the drawables found in the specified XML control.

Parameters:

control - XMLControlElement

copyAction

protected void copyAction(XMLControlElement control)

Copies objects found in the specified xml control.

Parameters:

control - the xml control

lostOwnership

public void lostOwnership(java.awt.datatransfer.Clipboard clipboard,
                          java.awt.datatransfer.Transferable contents)

Implementation of ClipboardOwner interface. Override this method to receive notification that data copied to the clipboard has changed.

Specified by:

lostOwnership in interface java.awt.datatransfer.ClipboardOwner

Parameters:

clipboard - Clipboard

contents - Transferable

setEnabledCopy

public void setEnabledCopy(boolean enable)

Enables the copy edit menu item.

Parameters:

enable - boolean

refreshGUI

protected void refreshGUI()

Description copied from class: OSPFrame

Refreshes the user interface in response to display changes such as Language.

Overrides:

refreshGUI in class OSPFrame

loadDisplayMenu

protected javax.swing.JMenu loadDisplayMenu()

Adds a Display menu to the menu bar.

Overrides:

loadDisplayMenu in class OSPFrame

loadToolsMenu

protected javax.swing.JMenu loadToolsMenu()

Adds a Tools menu to the menu bar.

Overrides:

loadToolsMenu in class OSPFrame

setCustomInspector

public void setCustomInspector(java.awt.Window w)

Sets a custom properties inspector window.

Parameters:

w - the new inspector window

inspectXML

public void inspectXML()

Inspects the drawing frame by using an xml document tree.

saveXML

public void saveXML()

getLoader

public static XML.ObjectLoader getLoader()

Returns an XML.ObjectLoader to save and load data for this program.

Returns:

the object loader