DRAWING STUFF

IMBEDDING A DRAWING WINDOW IN A GUI

1. INTRODUCTION

Often we wish to produce a second window from within our GUIs. In this example I present a fairly generic GUI that can be used as a template to produce a second winow (on the click of a button) containinmg a drawing area. The example application allows the user to input X and Y coordinates and a width and height for a rectangle or an oval (as directed by the user) to be drawn in a second window.

The example comprises three classes:

MyGUI: The top level (main) interface that contains "input buttons" for the user to enter the dimensions for the desired rectangle or oval and "output buttons" to produce the second windows containing the desired shape.
MyWindow: The second window to be produced.
MyCanvas: A class containg a paintComponent method that overides the method that comes with the Java Swing API and which is invoked automatically.

2. THE `MyGUI` CLASS

// MY GUI DRAWING EXAMPLE
// Frans Coenen
// University of Liverpool
// 2 September 2003

import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

// Other packages in here if any

public class MyGUI extends JFrame implements ActionListener{

    /* ------ FIELDS ------ */

    // Constants
    /** Minimum support value */
    private static final int MINIMUM = 1;
    /** Maximum support value */
    private static final int MAXIMUM = 200;

    // GUI features
    /** The text area to list results. */
    private JTextArea textArea;
    /** Input button for X coordinate input. */
    private JButton inputXcoordButton;
    /** Input button for Y coordinate input. */
    private JButton inputYcoordButton;
    /** Input button for width input. */
    private JButton inputWidthButton;
    /** Input button for height input. */
    private JButton inputHeightButton;
    /** Draw rectangle button. */
    private JButton drawRectangleButton;
    /** Draw Oval button. */
    private JButton drawOvalButton;
    /** Input panel */
    private JPanel inputPanel;
    /** Output panel */
    private JPanel outputPanel;

    // Other fields
    /** Rectanmgle width and height with defualt values. */
    private int width  = 10;
    private int height = 10;
    /** X and Y coordinates with default values. */
    private int xCoord = 10;
    private int yCoord = 10;

    /* ------ CONSTRUCTORS ------ */

    public MyGUI(String s) {
        super(s);
	
        // Create instance of AssocRuleMining
	
	// Content pane
        Container container = getContentPane();
        container.setBackground(Color.pink);
        container.setLayout(new BorderLayout(5,5)); // 5 pixel gaps
	
        // Create panels
	createInputButtonsPanel();
	createOutputButtonsPanel();
	
	// Button Panel
	JPanel buttonPanel = new JPanel();
	buttonPanel.setLayout(new GridLayout(1,2));
	buttonPanel.add(inputPanel);
	buttonPanel.add(outputPanel);
	container.add(buttonPanel,BorderLayout.NORTH);
	
	// Text area	
	textArea = new JTextArea(40, 15);
	textArea.setEditable(false);
        container.add(new JScrollPane(textArea),BorderLayout.CENTER);
	}

    /* CREATE INPUT PANEL. */
    /** Creates the buttons for the input panel. */

    private void createInputButtonsPanel() {
	// Create panel
	inputPanel = new JPanel();
	inputPanel.setLayout(new GridLayout(4,1));
	inputPanel.setBorder(BorderFactory.createTitledBorder("Input"));
	
	// Add buttons
	inputXcoordButton = new JButton("X Coordinate");
	inputXcoordButton.addActionListener(this);
        inputYcoordButton = new JButton("Y Coordinate");
        inputYcoordButton.addActionListener(this);
	inputWidthButton = new JButton("Width");
	inputWidthButton.addActionListener(this);
	inputHeightButton = new JButton("Height");
	inputHeightButton.addActionListener(this);
	
	// Add to panel
	inputPanel.add(inputXcoordButton);
	inputPanel.add(inputYcoordButton);
	inputPanel.add(inputWidthButton);
	inputPanel.add(inputHeightButton);
	}
	
    /* CREATE OUTPUT PANEL */
    /** Creates the buttons for the output panel. */

    private void createOutputButtonsPanel() {
	outputPanel = new JPanel();
	outputPanel.setLayout(new GridLayout(2,1));
	outputPanel.setBorder(BorderFactory.createTitledBorder("Output"));
	
	// Add buttons
	drawRectangleButton = new JButton("Draw Rectangle");
	drawRectangleButton.addActionListener(this);
	drawOvalButton = new JButton("Draw Oval");
	drawOvalButton.addActionListener(this);
	
	// add to panel
	outputPanel.add(drawRectangleButton);
	outputPanel.add(drawOvalButton);
	}
	
    /* ACTION PERFORMED */

    public void actionPerformed(ActionEvent event) {
        // Input panel
        if (event.getActionCommand().equals("X Coordinate")) inputXcoordinate();
        if (event.getActionCommand().equals("Y Coordinate")) inputYcoordinate();
        if (event.getActionCommand().equals("Width")) inputWidth();
        if (event.getActionCommand().equals("Height")) inputHeight();
	
	// Output panel
	if (event.getActionCommand().equals("Draw Rectangle")) drawRectangle();
        if (event.getActionCommand().equals("Draw Oval")) drawOval();
	}
	
    /* ---------------------------------------------------------------- */
    /*                                                                  */
    /*                              INPUT                               */
    /*                                                                  */
    /* ---------------------------------------------------------------- */
	
    /* INPUT X COORDINATE */
    private void inputXcoordinate() {
        int value = getInputValue("X coordinate","X COORDINATE");
        if (value >= MINIMUM) {
            xCoord = value;
            textArea.append("X coordinate = " + xCoord + "\n");
            }
        textArea.append("\n");
        }

    /* INPUT Y COORDINATE */
    private void inputYcoordinate() {
        int value = getInputValue("Y coordinate","Y COORDINATE");
        if (value >= MINIMUM) {
            yCoord = value;
            textArea.append("Y coordinate = " + yCoord + "\n");
            }
        textArea.append("\n");
        }

    /* INPUT WIDTH */
    private void inputWidth() {
        int value = getInputValue("Width","WIDTH");
        if (value >= MINIMUM) {
            width = value;
            textArea.append("Width = " + width + "\n");
            }
        textArea.append("\n");
        }

    /* INPUT HEIGHT */
    private void inputHeight() {
        int value = getInputValue("Height","HEIGHT");
        if (value >= MINIMUM) {
            height = value;
            textArea.append("Height = " + height + "\n");
            }
        textArea.append("\n");
        }

    /* GET INPUT VALUE */
    private int getInputValue(String label1, String label2) {        	
        int value;

        textArea.append("INPUT " + label2 + "\n---------------------\n");

        // Try-catch block
        try{
           while (true) {
               String stNum1 = JOptionPane.showInputDialog("Input " + label1 +
	       		". Integer value between " + MINIMUM + " and " + MAXIMUM);
	       value = Integer.parseInt(stNum1);
               if (value>=MINIMUM && value <= MAXIMUM) return(value);
               JOptionPane.showMessageDialog(null,
	       		label2 + " VALUE INPUT ERROR:\n" +
	       		"input = " + value +
	       		"\nsupport threshold input must be an integer " +
			"or a floating point number between " + MINIMUM +
			" and " +  MAXIMUM);		
	       }
	    }
        catch(NumberFormatException e) {
	    }
	
	// Default returm
	return(-99);
	}
	
    /* ---------------------------------------------------------------- */
    /*                                                                  */
    /*                             OUTPUT                               */
    /*                                                                  */
    /* ---------------------------------------------------------------- */
    	
    /* DRAW RECTANGLE */
    /** Commences processes of drawing a rectangle to the screen in a
    separate window. */
    private void drawRectangle() {
	textArea.append("Draw Rectangle\n---------------------\n");
	
	MyWindow newWindow = new
	    		    MyWindow("Rectangle",xCoord,yCoord,width,height);	
        newWindow.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
	textArea.append("Done\n\n");
	}

    /* DRAW OVAL */
    /** Commences processes of drawing a oval to the screen in a
    separate window. */
    private void drawOval() {
	textArea.append("Draw Oval\n---------------------\n");
	
	MyWindow newWindow = new
	    		    MyWindow("Oval",xCoord,yCoord,width,height);	
        newWindow.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
	textArea.append("Done\n\n");
	}
    	
    /* ------------------------------------------------------- */
    /*                                                         */
    /*                         MAIN METHOD                     */
    /*                                                         */
    /* ------------------------------------------------------- */
    	
    /* MAIN METHOD */

    public static void main(String[] args) throws IOException {
	
	// Create instance of class AprioriTgui
	MyGUI newGUI = new MyGUI("MY EXAMPLE GUI");

	// Make window vissible
	newGUI.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
	newGUI.setSize(400,400);
        newGUI.setVisible(true);
        }
    }

Table 1: The MyGUI classM

3. THE `NyWindow` CLASS

// MY WINDOW EXAMPLE CLASS
// Frans Coenen
// MOnday 30 June 2003
// The University of Liverpool, UK

import java.awt.*;
import java.awt.geom.*;

// Java extension packages
import javax.swing.*;

// Other packages in here if any

public class MyWindow extends JFrame {

    // ------------------- FIELDS ------------------------

    /* CONSTANTS */

    static final int CANVAS_WIDTH  = 400;
    static final int CANVAS_HEIGHT = 400;

    // ------------------ CONSTRUCTORS -------------------

    public MyWindow(String type, int x, int y, int w, int h) {
        super("My Window");
	
	// Create drawing area
	MyCanvas canvas = new MyCanvas(type,x,y,w,h);
	canvas.setBackground(Color.white);
	canvas.setPreferredSize(new Dimension(CANVAS_WIDTH,CANVAS_HEIGHT));
	
	// Create scroll pane
        JScrollPane sp1 = new JScrollPane(canvas);
	
	// Get container and add scroll pane
        Container container = getContentPane();
        container.setBackground(Color.pink);
	
	container.add(sp1);
        setSize(300,300);
        setVisible(true);
        }

    // ------------------ METHODS ------------------------
	
    /* Include any additional methods that might need to be called
    from the constructor in here. */
    }

Table 2: The NyWindow classM

4. THE `MyCanvas` CLASS

// MY CANVAS DRAWING EXAMPLE
// Frans Coenen
// University of Liverpool
// 27 June 2003

import java.awt.*;

// Java extension packages
import javax.swing.*;

// Other packages if any

public class MyCanvas extends JPanel {

    /* FIELDS */

    private int xCoord, yCoord, width, height;
    private String type;

    /* CONSTRUCTOR */

    public MyCanvas(String t, int x, int y, int w, int h) {
        super();
	
        // Set fields
        type   = t;
        xCoord = x;
        yCoord = y;
        width  = w;
        height = h;
	}

    /* METHODS. Top level method sgould overwrite paiontComponent
    method in Java Swing API but can include calls to any other
    methods as desired. */

    public void paintComponent(Graphics g) {

        // Make the panel opaque
        super.paintComponent(g);
	
        // draw

	g.setColor(Color.pink);
        if (type.equals("Rectangle")) {
	    g.fillRect(xCoord,yCoord,width,height);	
	    g.setColor(Color.red);
	    g.drawRect(xCoord,yCoord,width,height);
	    }
        else if (type.equals("Oval")) {
	    g.fillOval(xCoord,yCoord,width,height);	
	    g.setColor(Color.red);
	    g.drawOval(xCoord,yCoord,width,height);
	    }
        }
    }

Table 3: The MyCanvas classM

5. EXAMPLE OUTPUT

Figure 1 shows the top level GUI and Figure 2 some eaxmple output (an oval ibn this case).

Figure 1: The MyExampleGUI window

Figure 2: Example output (oval)

1. INTRODUCTION

2. THE MyGUI CLASS

3. THE NyWindow CLASS

4. THE MyCanvas CLASS

5. EXAMPLE OUTPUT

2. THE `MyGUI` CLASS

3. THE `NyWindow` CLASS

4. THE `MyCanvas` CLASS