CS 335/535 Web Programming - Java Graphics Programming

• Color - methods and constants for manipulating colors
• Font - methods and constants for manipulating fonts
• FontMetrics - methods for obtaining font information
• Polygon - methods for creating polygons
• Graphics - methods for drawing strings, lines, rectangles and other shapes
• Toolkit - methods for getting graphical information from a system

1. public void paint (Graphics g) - called after init and start
2. public void repaint()
3. public void update (Graphics g)

import java.applet.Applet;
import java.awt.Graphics;

public class DrawSCB extends Applet {
	private String s = "web programming";
	private char c[] = {'c','h','a','r','s',' ','8'};
	private byte b[] = {'b','y','t','e',1,2,3};
public void paint (Graphics g)
{
	// writes the string at position x=100, y=25
	g.drawString(s, 100, 25);
	// writes characters 1,2,3 [har] at position x=100, y=50
	g.drawChars (c, 1, 3, 100, 50);
	// writes bytes 0,1,2,3,4 [byte1] at position x=100, y=75
	g.drawBytes(b, 0, 5, 100, 75);
}
}

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Color;

public class ShowColors extends Applet {
	private int red, green, blue;
	
	public void init()
	{
		red = 100;
		blue = 255;
		green = 125;
	}
	public void paint (Graphics g)
	{
		g.setColor (new Color (red, green, blue) );
		g.drawString ("Welcome to CS335", 50, 33);
		showStatus ("Current RGB: " + g.getColor().toString() );
	}
}

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Font;

public class DemoFont extends Applet {
	private Font fon;
	
	public void init()
	{
		fon = new Font ("Courier", Font.ITALIC + Font.BOLD, 24);
	}
	public void paint (Graphics g)
	{
		int style, size;
		String str, name;
		
		g.setFont (fon);
		style = fon.getStyle();
		
		if ( style == Font.PLAIN)
			str = "Plain";
		else if (style == Font.BOLD)
			str = "Bold";
		else if (style == Font.ITALIC)
			str = "Italic";
		else
			str = "Bold italic";
		
		size = fon.getSize();
		str += size + " point ";
		name = fon.getName();
		str += name;
		
		g.drawString (str, 20, 40);
		g.drawString ("Font family is " + fon.getFamily(), 20, 60);
	}
}

1. g.drawRect(x, y, width, height)
2. g.fillRect(x, y, width, height) [draws a solid rectangle]
3. g.clearRect(x, y, width, height) [draws a rectange in the current background color]

1. g.drawRoundRect(x, y, width, height, arcwidth, archeight) [draws a rectangle with rounded corners in the current color]
2. g.fillRoundRect (x, y, width, height, arcwidth, archeight) [draws a solid rectangle with rounded corners in the current color]

1. g.draw3DRect (x, y, width, height, raised) [draws a 3-d rectangle in the current color; rectangle is raised if raised=true]
2. g.fill3DRect (x, y, width, height, raised)

1. g.drawOval(x, y, width, height) [draws an oval bounded by a rectangle in the current color]
2. g.fillOval (x, y, width, height) [draws an solid oval bounded by a rectangle in the current color]

1. g.drawArc(x, y, width, height, startAngle, arcAngle) [draws an arc bounded by a rectangle in the current color from the starting angle]
2. g.fillArc (x, y, width, height, startAngle, arcAngle) [draws an solid arc bounded by a rectangle in the current color from the starting angle]

1. g.drawPolygon(xPoints, yPoints, nbrPoints) [draws a polygon]
2. g.fillPolygon(xPoints, yPoints, nbrPoints) [draws a solid polygonin the current color]
3. g.Polygon(xPoints, yPoints, nbrPoints) [constructs a new polygon object]

1. g.copyArea(x, y, width, height, horizontalDistance, verticalDistance) [copies a screen area relative to its current location]

   import java.applet.Applet;
   import java.awt.Graphics;
   
   public class DemoCopyArea extends Applet {
   	int xValues[] = {20, 40, 50, 30, 20, 15, 20};
   	int yValues[] = {20, 20, 30, 50, 50, 30, 20};
   
   	private Polygon p2;
   
   	public void init ()
   	{
   		p2 = new Polygon();
   		p2.addPoint (70, 70);
   		p2.addPoint (90, 70);
   		p2.addPoint (100, 80);
   		p2.addPoint (80, 100);
   		p2.addPoint (70, 100);
   		p2.addPoint (65, 80);
   		p2.addPoint (60, 60);
   	}
   	public void paint (Graphics g)
   	{
   		g.drawPolygon (xValues, yValues, 7);
   
   		g.fillPolygon (p2);
   
   		g.copyArea (0, 0, 100, 100, 140, 10 );
   	}
   }
   

1. public Label()
2. public Label( String s)

1. public Button () [no button label]
2. public Button (String s) [button label]

1. public TextField()
2. public TextField( int columns)
3. public TextField( String s)
4. public TextField(String s, int columns)

1. public int countItems()
2. public String getItem (int index)
3. public sychronized void addItem (String s)
4. public String getSelectedItem ()
5. public int getSelectedIndex ()

1. public Checkbox()
2. public Checkbox( String s )
3. public Checkbox( String s, CheckboxGroup c, boolean selected) - radio button
4. public CheckboxGroup()

import java.applet.Applet;
import java.awt.*;

public class MyChoice extends Applet {
	private Choice choiceButton;
	private TextField t;
	private Font f;
	private Checkbox checkBold, checkItalic;

	public void init()
	{
		choiceButton = new Choice();
		t = new TextField( "Sample Text", 16);
		t.setEditable(false);

		choiceButton.addItem( "TimesRoman");
		choiceButton.addItem( "Courier");
		choiceButton.addItem( "Helvitica");
		add (choiceButton);

		checkBold = new Checkbox("Bold");
		checkItalic = new Checkbox();
		checkItalic.setLabel ("Italic");
		add (checkBold);
		add (checkItalic);
		
		f = new Font (choiceButton.getItem(0), Font.PLAIN, 14);
		t.setFont (f);

		add (t);
	}

	public boolean action (Event e, Object o)
	{
		String s;
		int bo, it;
	
		if (e.target instanceof Choice || e.target instanceof Checkbox)
		{
			if (checkBold.getState() == true)
				bo = Font.BOLD;
			else
				bo = Font.PLAIN;
			if (checkItalic.getState() )
				it = Font.ITALIC;
			else
				it = Font.PLAIN;

			f = new Font (choiceButton.getSelectedItem(), bo + it, 14);

			t.setFont(f);

			s = "Number of items: " + choiceButton.countItems();
			s += "     Current index: " + choiceButton.getSelectedIndex();

			showStatus (s);
		}
		return true;
	}
}

1. public List()
2. public List( int items, boolean multipleSelections)

import java.applet.Applet;
import java.awt.*;

public class MyList extends Applet {
	private List stateList, copyList;
	private Button copy;

	public void init()
	{
		stateList = new List (5, true);
		copyList = new List (5, false);
		copy = new Button ("Copy >>>");

		stateList.addItem("New Mexico");
		stateList.addItem("New Jersey");
		stateList.addItem("New York");
		stateList.addItem("Alaska");
		stateList.addItem("Hawaii");
		stateList.addItem("Ohio");
		stateList.addItem("Iowa");
		stateList.addItem("Maine");
		stateList.addItem("Texas");

		add (stateList);
		add (copy);
		add (copyList);
	}

	public boolean action (Event e, Object o)
	{
		String states[];
	
		if (e.target == copy)
		{
			states = stateList.getSelectedItems();
	
			for (int i = 0; i < states.length; i++)
				copyList.addItem ( states[i] );
		}
		return true;
	}
}

import java.applet.Applet;
import java.awt.*;

public class TwoPanels extends Applet {
	private Panel pan1, pan2;
	private Label lab1, lab2;

	public void init()
	{
		pan1 = new Panel();
		pan2 = new Panel();
		lab1 = new Label (" first panel ");
		lab2 = new Label (" second panel ");

		pan1.setBackground (Color.yellow);
		pan2.setBackground (Color.pink);

		pan1.add (lab1);
		pan2.add (lab2);

		add (pan1);
		add (pan2);
	}
}

1. public boolean mouseDown ( Event e, int x, int y) // occurs when mouse button is pressed
2. public boolean mouseUp ( Event e, int x, int y) // occurs when mouse button is released
3. public boolean mouseMove ( Event e, int x, int y) // occurs when mouse is moved
4. public boolean mouseExit ( Event e, int x, int y) // occurs when mouse pointer leaves area of component
5. public boolean mouseEnter ( Event e, int x, int y) // occurs when mouse pointer enters the area of a component
6. public boolean mouseDrag ( Event e, int x, int y) // occurs when mouse button is pressed and the mouse is moved

Drag Applet

1. public boolean keyDown (Event e, int key) // occurs when key is pressed (unicode for key)
2. public boolean keyUp (Event e, int key) // occurs when key is released

1. FlowLayout - default for applets and panels. [Places components sequentially (left to right) in order they were added.]
2. BorderLayout - arranges components into five areas:North, South, East, West, Center
3. GridLayout - arranges components into rows and columns

1. public final static int CENTER
2. public final static int LEFT
3. public final static int RIGHT
4. public FlowLayout()
5. public FlowLayout(int alignment)
6. public FlowLayout(int alignment, int horizontal-gap, int vertical-gap)

1. public BorderLayout()
2. public BorderLayout(int spacing)

1. public GridLayout(int rows, int columns)
2. public GridLayout(int rows, int columns, int horizontal-spacing, int vertical-spacing)

1. public TextArea( int rows, int columns)
2. public TextArea( String s, int rows, int columns)