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There are two main toolkits for GUI development in Java, SWT and Swing. While either can be used for dialog creation, Deducer has a number of specialized Swing components specifically focused on statistical GUI creation. This page assumes a basic familiarity with Swing, and will take you through the process of building a dialog to create a scatter plot. There are many Swing tutorials available, including one written by Sun.

RDialog

RDialog extends Swing's JDialog, and makes it easy to create a dialog with memory. Memory is an important aspect of a statistical analysis dialog, because it is rare that the user has specified all of the analysis options correctly the first time. Anytime a Deducer widget is added to the dialog via add, it's state is tracked, and saved when the dialog is successfully completed. Then when the dialog is re-opened, it sets the widgets' states to their saved value. This is all done transparently. The only thing that the programmer needs to do is inform RDialog when it is successfully competed.

Important Methods:

run()

This is the preferred way of opening up the dialog. It sets the widget states to their appropriate values, makes the dialog visible, and handles compatibility with non-JGR consoles.

reset()

Sets widgets to their default states.

setToLast()

Sets widgets to the last completed state of the dialog

completed()

Dialog completed.

setOkayCancel(boolean showReset,boolean isRun,ActionListener lis)

Adds Okay/Run, Cancel, and Reset buttons to the bottom right of the dialog

addHelpButton(String pageLocation)

Adds a help button to the botom left. pageLocation is the URL relative to http://www.deducer.org/pmwiki/

initGUI()

Called upon construction. Override this to add in GUI widgets/components

By default RDialog uses AnchorLayout as it's layout manager. Though this can be changed. The classes are located at:

import org.rosuda.JGR.layout.AnchorConstraint;
import org.rosuda.JGR.layout.AnchorLayout;

Widgets

Widgets are easy to use Swing components provided by Deducer.

Auto-generated Documentation for each of these is available: Widget JavaDocs.

Adding a Widget

Widgets can be added just as any other component.

		SliderWidget slider = new SliderWidget("Alpha level",new String[]{"Transparent","Opaque"});
		anRDialog.add(slider, new AnchorConstraint(610, 978, 840, 460, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL));

In the above code, a new slider is added to the RDialog anRDialog. In this case, anRDialog uses AnchorLayout, so the slider is added with an AnchorConstraint. Each of the numbers represents the distance from either the left or the top of the dialog for each side of the slider (top, right, bottom and left). Because all of the constraints are AnchorConstraint.ANCHOR_REL, the numbers represent relative positions going from 1 (left/top edge) to 1000 (right/ bottom edge). When the dialog is resized, the slider will be resized proportionally. The constraint can also be AnchorConstraint.ANCHOR_ABS, in which case the number associated with that side is the absolute number of pixels between the component's edge, and that of the dialog.

		variableSelector = new VariableSelectorWidget();
		anRDialog.add(variableSelector, new AnchorConstraint(12, 428, 900, 12, 
				AnchorConstraint.ANCHOR_ABS, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_ABS));

The above code creates a new variable selector. Because the top and left constraints are AnchorConstraint.ANCHOR_ABS, there are 12 pixels between the left side of the dialog, and the left side of the selector. Similarly, there are 12 pixels between the top of the selector and the top of the dialog, regardless of how the dialog is resized.

Finally, the constraint can be AnchorConstraint.ANCHOR_NONE, in which case the position of the side is determined by the preferred size of the component (set with setPreferredSize).

Creating a Scatter Plot Dialog

We can make a scatter plot dialog easily using the above tools. We will extend RDialog. We will also implement ActionListener so that we can respond to the user pressing the buttons at the bottom of the dialog.

package example;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JOptionPane;

import org.rosuda.JGR.layout.AnchorConstraint;
import org.rosuda.deducer.Deducer;
import org.rosuda.deducer.widgets.*;


public class PlotRDialog extends RDialog implements ActionListener{

	private VariableSelectorWidget variableSelector;
	private SingleVariableWidget yaxis;
	private SingleVariableWidget xaxis;
	private SliderWidget slider;



	public void initGUI(){
		super.initGUI();


		variableSelector = new VariableSelectorWidget();
		this.add(variableSelector, new AnchorConstraint(12, 428, 900, 12, 
				AnchorConstraint.ANCHOR_ABS, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_ABS));
		variableSelector.setPreferredSize(new java.awt.Dimension(216, 379));
		variableSelector.setTitle("Data");

		yaxis = new SingleVariableWidget("y axis",variableSelector);
		this.add(yaxis, new AnchorConstraint(121, 978, 327, 460, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL));
		yaxis.setPreferredSize(new java.awt.Dimension(276, 63));

		xaxis = new SingleVariableWidget("x axis",variableSelector);
		this.add(xaxis, new AnchorConstraint(337, 978, 540, 460, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL));
		xaxis.setPreferredSize(new java.awt.Dimension(276, 63));

		slider = new SliderWidget("Alpha level",new String[]{"Transparent","Opaque"});
		this.add(slider, new AnchorConstraint(610, 978, 840, 460, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL, 
				AnchorConstraint.ANCHOR_REL, AnchorConstraint.ANCHOR_REL));
		slider.setPreferredSize(new java.awt.Dimension(187, 44));
		slider.setDefaultModel(new Integer(100));

		this.setTitle("Scatter Plot");

		setOkayCancel(true,true,this);   //put Run, Reset, Cancel buttons in place, and register this as it's listener
		addHelpButton("pmwiki.php");     //Add help button pointing to main manual page
		this.setSize(555, 445);
	}

	public void actionPerformed(ActionEvent e) {
		String cmd = e.getActionCommand();

		if(cmd=="Run"){
			String xvar = xaxis.getSelectedVariable();
			String yvar = yaxis.getSelectedVariable();
			String data = variableSelector.getSelectedData();
			String alpha = new Double(((double) slider.getValue())/100.0).toString();
			if(yvar==null || xvar==null || data==null){
				JOptionPane.showMessageDialog(this, "You must specify both an x and y variable");
				return;
			}

			String command = "qplot("+xvar+", "+yvar+", data="+data+",alpha=I("+alpha+"))";

			Deducer.execute(command);		//execute command as if it had been entered into the console
			this.setVisible(false);
			completed();	//dialog completed
		}else if(cmd=="Cancel")
			this.setVisible(false);
		else if(cmd=="Reset")
			reset();
	}

}

The first method (initGUI) overrides the the RDialog method, and is used to set up the four widgets. The actionPerformed method is called when the "Run", "Cancel" or "Reset" buttons are pressed. When "Run" is pressed, an call to qplot in the ggplot2 package is constructed. It is then executed using Deducer.execute.

The above Class is present in the DeducerPlugInExample package, and can be viewed with:

R> library(DeducerPlugInExample)
R> scatter <- new(J("example.PlotRDialog"))
R> scatter$run()