Computer Graphics

GUI - Examples

Mouse and Keyboard Events

Example 1: Follow the Mouse

Program captures mouse position and uses that as starting point for drawing a polygon.

import java.awt.*;

import java.awt.event.*;

import java.nio.IntBuffer;

import net.java.games.jogl.*;

import net.java.games.jogl.util.*;

public class PolyDraw

{

public static GLCanvas canvas;

public static void main(String[] args)

{

Frame frame = new Frame("Follow the Mouse");

canvas = GLDrawableFactory.getFactory().createGLCanvas(new GLCapabilities());

canvas.addGLEventListener(new Renderer());

frame.add(canvas);

frame.setSize(500, 500);

frame.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

frame.show();

canvas.requestFocus();

}

static float xpos, ypos; // mouse position

static class Renderer extends Frame implements GLEventListener, KeyListener, MouseListener

{

public class cPt2D {

public float x, y;

cPt2D(float xcoord, float ycoord){

x= xcoord;

y= ycoord;

}

cPt2D ( ){

x = 0.0f;

y = 0.0f;

}

};

public void translatePolygon (GL gl, cPt2D [] verts, int nVerts, float tx, float ty)

{

int k;

cPt2D [] vertsNew = new cPt2D[4];

for (k = 0; k < nVerts; k++)

vertsNew[k] = new cPt2D( );

for (k = 0; k < nVerts; k++) {

vertsNew [k].x = verts [k].x + tx;

vertsNew [k].y = verts[k].y + ty;

}

gl.glBegin (GL.GL_POLYGON);

for (k = 0; k < nVerts; k++)

gl.glVertex2f (vertsNew[k].x, vertsNew[k].y);

gl.glEnd ( );

}

int i=0; // color counter

public void display(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

float [][] CLUT ={{1.0f,0.0f,0.0f}, {1.0f,0.5f,0.0f}, {1.0f,1.0f,0.0f}, {0.0f,1.0f,0.0f},{0.0f,0.0f,1.0f},{1.0f,0.0f,1.0f},

{0.5f,0.0f,0.5f}, {1.0f,0.0f,0.5f}};

//gl.glClear (GL.GL_COLOR_BUFFER_BIT); // Set display window to color.

//above line commented out so framebuffer is not cleared

gl.glMatrixMode (GL.GL_MODELVIEW);

gl.glLoadIdentity();

cPt2D [] polygon = new cPt2D[4];

polygon[0] = new cPt2D(0.0f,0.0f);

polygon[1] = new cPt2D(50.0f,0.0f);

polygon[2] = new cPt2D(50.0f,50.0f);

polygon[3] = new cPt2D(0.0f,50.0f);

gl.glColor3fv (CLUT[i%8]);

translatePolygon(gl, polygon, 4, xpos, ypos);

i++; // color counter

}

public void init(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

gl.glClear (GL.GL_COLOR_BUFFER_BIT);

// Set display window to color.

gl.glMatrixMode (GL.GL_PROJECTION);

gl.glClearColor (0.0f, 0.0f, 0.0f, 0.0f);

//set background to black

glu.gluOrtho2D (0, 499.0, 0.0, 499.0); // define drawing area

gLDrawable.addKeyListener(this);

gLDrawable.addMouseListener(this);

}

public void displayChanged(GLDrawable gLDrawable, boolean modeChanged, boolean deviceChanged)

{

}

public void reshape(GLDrawable gLDrawable, int x, int y, int width, int height)

{

}

public void keyPressed(KeyEvent e)

{

if (e.getKeyCode() == KeyEvent.VK_ESCAPE)

System.exit(0);

}

public void keyReleased(KeyEvent e) {}

public void keyTyped(KeyEvent e) {}

public void mouseEntered(MouseEvent event) {}

public void mouseExited(MouseEvent event) {}

public void mouseReleased(MouseEvent event) {}

public void mouseClicked(MouseEvent event) {}

public void mousePressed(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale to widow from viewport

xpos = (float)((x/width)*500);

ypos = (float)((y/height)*500);

ypos = 500.0f -ypos;

canvas.display();

}

}

}

Example 2: Drawing with the Mouse

Program captures mouse position and uses that as starting point for drawing a line.

import java.awt.*;

import java.awt.event.*;

import java.nio.IntBuffer;

import net.java.games.jogl.*;

import net.java.games.jogl.util.*;

public class WhiteBoard1

{

public static GLCanvas canvas;

public static void main(String[] args)

{

Frame frame = new Frame("White Board 1");

canvas = GLDrawableFactory.getFactory().createGLCanvas(new GLCapabilities());

canvas.addGLEventListener(new Renderer());

frame.add(canvas);

frame.setSize(500, 500);

frame.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

frame.show();

canvas.requestFocus();

}

static float xpos=0.0f, ypos=0.0f, lastX=0.0f, lastY=0.0f;

static int drawcount=0;//checks to see if mouse has entered before

static class Renderer extends Frame implements GLEventListener, KeyListener, MouseListener, MouseMotionListener

{

int i=0;

public void display(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

float [][] CLUT ={{1.0f,0.0f,0.0f},{1.0f,0.5f,0.0f},{1.0f,1.0f,0.0f},

{0.0f,1.0f,0.0f},{0.0f,0.0f,1.0f},{1.0f,0.0f,1.0f},

{0.5f,0.0f,0.5f}, {1.0f,0.0f,0.5f}};

//gl.glClear (GL.GL_COLOR_BUFFER_BIT); // Set display window to color.

gl.glMatrixMode (GL.GL_MODELVIEW);

gl.glLoadIdentity();

gl.glColor3f(1.0f,1.0f,1.0f);

//drawcount used to make sure it does not draw line from zero on loading

if (drawcount!=0){

gl.glBegin(GL.GL_LINE_STRIP);

gl.glVertex2f(lastX,lastY);

gl.glVertex2f(xpos,ypos);

gl.glEnd();

}

drawcount++;

}

public void init(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

gl.glClear (GL.GL_COLOR_BUFFER_BIT); // Set display window to color.

gl.glMatrixMode (GL.GL_PROJECTION);

gl.glClearColor (0.0f, 0.0f, 0.0f, 0.0f); //set background to white

glu.gluOrtho2D (0.0f, 500.0f, 0.0f, 500.0f); // define drawing area

gLDrawable.addKeyListener(this);

gLDrawable.addMouseListener(this);

gLDrawable.addMouseMotionListener(this);

}

public void displayChanged(GLDrawable gLDrawable, boolean modeChanged, boolean deviceChanged)

{

}

public void reshape(GLDrawable gLDrawable, int x, int y, int width, int height)

{

}

public void keyPressed(KeyEvent e)

{

if (e.getKeyCode() == KeyEvent.VK_ESCAPE)

System.exit(0);

}

public void keyReleased(KeyEvent e) {}

public void keyTyped(KeyEvent e) {

}

public void mouseEntered(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

lastX = (float)((x/width)*500);

lastY = (float)((y/height)*500);

lastY = 500.0f - lastY;

}

public void mouseExited(MouseEvent event) {}

public void mouseReleased(MouseEvent event) {}

public void mouseClicked(MouseEvent event) {}

public void mousePressed(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

lastX = (float)((x/width)*500);

lastY = (float)((y/height)*500);

lastY = 500.0f - lastY;

}

public void mouseMoved(MouseEvent event) {}

public void mouseDragged(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

xpos = (float)((x/width)*500);

ypos = (float)((y/height)*500);

ypos = 500.0f -ypos;

canvas.display();

lastX = xpos;

lastY = ypos;

}

}

}

Example 3: Whiteboard Program

Program captures mouse position and uses that as starting point for drawing a line and drawing text.

import java.awt.*;

import java.awt.event.*;

import java.nio.IntBuffer;

import net.java.games.jogl.*;

import net.java.games.jogl.util.*;

public class WhiteBoard2

{

public static GLCanvas canvas;

public static void main(String[] args)

{

Frame frame = new Frame("White Board 1");

canvas = GLDrawableFactory.getFactory().createGLCanvas(new GLCapabilities());

canvas.addGLEventListener(new Renderer());

frame.add(canvas);

frame.setSize(500, 500);

frame.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

frame.show();

canvas.requestFocus();

}

static float xpos=0.0f, ypos=0.0f, lastX=0.0f, lastY=0.0f;

static int drawcount=0;

static String s = "";

static boolean line=true;

static class Renderer extends Frame implements GLEventListener, KeyListener, MouseListener, MouseMotionListener

{

int i=0;

public void display(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

final GLUT glut = new GLUT();

float [][] CLUT ={{1.0f,0.0f,0.0f},{1.0f,0.5f,0.0f},{1.0f,1.0f,0.0f},

{0.0f,1.0f,0.0f},{0.0f,0.0f,1.0f},{1.0f,0.0f,1.0f},

{0.5f,0.0f,0.5f}, {1.0f,0.0f,0.5f}};

//gl.glClear (GL.GL_COLOR_BUFFER_BIT); // Set display window to color.

gl.glMatrixMode (GL.GL_MODELVIEW);

gl.glLoadIdentity();

gl.glColor3f(1.0f,1.0f,1.0f);

if (line)

{

//drawcount used to make sure it does not draw line from zero on loading

if (drawcount!=0){

gl.glBegin(GL.GL_LINE_STRIP);

gl.glVertex2f(lastX,lastY);

gl.glVertex2f(xpos,ypos);

gl.glEnd();

}

drawcount++;

}

else

{

gl.glRasterPos2f(lastX,lastY);

glut.glutBitmapString(gl, 5, s);

lastX += glut.glutBitmapLength(5, s);

}

}

public void init(GLDrawable gLDrawable)

{

final GL gl = gLDrawable.getGL();

final GLU glu = gLDrawable.getGLU();

gl.glClear (GL.GL_COLOR_BUFFER_BIT); // Set display window to color.

gl.glMatrixMode (GL.GL_PROJECTION);

gl.glClearColor (0.0f, 0.0f, 0.0f, 0.0f); //set background to white

glu.gluOrtho2D (0.0f, 500.0f, 0.0f, 500.0f); // define drawing area

gLDrawable.addKeyListener(this);

gLDrawable.addMouseListener(this);

gLDrawable.addMouseMotionListener(this);

}

public void displayChanged(GLDrawable gLDrawable, boolean modeChanged, boolean deviceChanged)

{

}

public void reshape(GLDrawable gLDrawable, int x, int y, int width, int height)

{

}

public void keyPressed(KeyEvent e)

{

if (e.getKeyCode() == KeyEvent.VK_ESCAPE)

System.exit(0);

}

public void keyReleased(KeyEvent e) {}

public void keyTyped(KeyEvent e) {

s = String.valueOf(e.getKeyChar());

line = false;

canvas.display();

}

public void mouseEntered(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

lastX = (float)((x/width)*500);

lastY = (float)((y/height)*500);

lastY = 500.0f - lastY;

}

public void mouseExited(MouseEvent event) {}

public void mouseReleased(MouseEvent event) {}

public void mouseClicked(MouseEvent event) {}

public void mousePressed(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

lastX = (float)((x/width)*500);

lastY = (float)((y/height)*500);

lastY = 500.0f - lastY;

}

public void mouseMoved(MouseEvent event) {}

public void mouseDragged(MouseEvent event) {

Component c = event.getComponent();

double width = c.getWidth();

double height = c.getHeight();

double x = event.getX();

double y = event.getY();

// scale from image space to object space

xpos = (float)((x/width)*500);

ypos = (float)((y/height)*500);

ypos = 500.0f -ypos;

line = true;

canvas.display();

lastX = xpos;

lastY = ypos;

}

}

}