Problem in a drawing program

Question

Dear experts,
While working on a program,i am having a problem which is just killing me.This is a simple drawing program.On clicking draw button,user
can do free hand drawing.On clicking line he can stretch line to any
coordinate.Similarily do erasing etc.
Problem underlies in rectangle part.I am using some conditions.
Conditions are based on analysis.Fixx and Fixy are the points
when mouse is pressed.
Prevx and Prevy are coordinates which are stored before retrieving
newer ones.x and y are new coordinates.
I have marked the relevant code as part of code for easy understanding.
Problem is in behaviour for rectangle.If i draw twoards either side
it works well but the moment i drag right ,left,up down ,i get
patched near origin(fixed point) from where mouse was pressed ie
fixx,fixy.
I recommend if this could be copied as it is and run,the problem will come to light better.
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
public class FProf extends JPanel implements MouseListener,ActionListener,MouseMotionListener
JFrame main_window;
int draw_mode,erase_mode,line_mode,box_mode;
double fixx,fixy;
double initx,inity;
double x,y;
JButton b_draw;
JButton b_erase;
JButton b_line;
JButton b_rec;
JPanel draw_panel;
JPanel bt_panel;
Graphics2D g2;
Point p;//Mouse pointer
Image image=null;
double prevx,prevy;
double c1,c2,c3,c4,c5,c6,c7,c8;
Stroke[] linestyles = new Stroke[] {
new BasicStroke(25.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL),
new BasicStroke(25.0f, BasicStroke.CAP_SQUARE,BasicStroke.JOIN_MITER),
new BasicStroke(1.0f, BasicStroke.CAP_ROUND,BasicStroke.JOIN_MITER),
new BasicStroke(25.0f, BasicStroke.CAP_ROUND,
BasicStroke.JOIN_ROUND), };
FProf()
draw_mode=0; //Inactive
erase_mode=0; //Inactive
addMouseListener(this);
addMouseMotionListener(this);
GridLayout l=new GridLayout(4,4);
main_window=new JFrame("Fountain Prof V.200");
bt_panel=new JPanel();
b_draw=new JButton ("Draw");
b_draw.addActionListener(this);
b_erase=new JButton("Erase");
b_erase.addActionListener(this);
b_line=new JButton("Line");
b_line.addActionListener(this);
b_rec=new JButton ("Box");
b_rec.addActionListener(this);
main_window.getContentPane().setLayout(new BorderLayout());
main_window.getContentPane().add("Center",this);
bt_panel.setLayout(l);
bt_panel.add(b_draw);
bt_panel.add(b_erase);
bt_panel.add(b_line);
bt_panel.add(b_rec);
main_window.getContentPane().add("East",bt_panel);
main_window.setSize(800,600);
main_window.show();
private void draw()
if ((erase_mode==1) &&(draw_mode==0) &&(line_mode==0)&&(box_mode==0)) {
g2.setPaintMode();
g2.setColor(Color.white);
g2.setStroke(linestyles[3]); // Select the line style to use
g2.draw(new Line2D.Double(initx,inity,x,y));
repaint();
else if ((draw_mode==1) && (line_mode==0) &&(erase_mode==0)&&(box_mode==0))
g2.setPaintMode();
g2.setColor(Color.black);
g2.setStroke(linestyles[2]); // Select the line style to use
g2.draw(new Line2D.Double(initx,inity,x,y));
repaint();
else if ((draw_mode==0) && (erase_mode==0) &&(line_mode==1)&&(box_mode==0))
repaint();
        else if ((draw_mode==0) && (erase_mode==0) &&(line_mode==0)&&(box_mode==1))
        repaint();
public void paintComponent(Graphics g)
super.paintComponent(g);
if (image == null)
System.out.print(getHeight());
g2=(Graphics2D) g;
image = createImage(getWidth(), getHeight());
g2 = (Graphics2D)image.getGraphics();
g2.setColor(Color.white);
g2.fillRect(0, 0, getWidth(), getHeight());
g2.setColor(Color.black);
Rectangle r = g.getClipBounds();
g.drawImage(image, r.x, r.y, r.width+r.x, r.height+r.y, r.x, r.y, r.width+r.x, r.height+r.y, null);
public void mouseReleased(MouseEvent e)
public void mouseEntered(MouseEvent e)
public void mouseExited(MouseEvent e)
public void change_cursor()
Toolkit tk=Toolkit.getDefaultToolkit();
if ((draw_mode==1)&&(erase_mode==0)) {
Image img=tk.getImage("Pen.gif");
Cursor dym=tk.createCustomCursor(img,new Point(10,10),null);
setCursor(dym);
else if ((erase_mode==1)&&(draw_mode==0)) {
Image img=tk.getImage("eraser.gif");
Cursor dym=tk.createCustomCursor(img,new Point(10,10),null);
setCursor(dym);
public void mouseClicked(MouseEvent e)
public void mouseDragged(MouseEvent e)
Point p;
if ((draw_mode ==1)||(erase_mode==1)) {
initx=x;inity=y;
p=e.getPoint();
x=p.getX();
y=p.getY();
draw();
if ((line_mode==1)&&(box_mode==0)) {
if (mousehasmoved(e)) {
prevx=x;prevy=y;
p=e.getPoint();
x=p.getX();
y=p.getY();
g2 = (Graphics2D)image.getGraphics();
g2.setColor(Color.black);
g2.setXORMode(Color.white);
g2.draw(new Line2D.Double(fixx,fixy,prevx,prevy)); //erasing previous line
draw();
g2.draw(new Line2D.Double(fixx,fixy,x,y)); //redrawing newer one
draw();
if ((line_mode==0)&&(box_mode==1)) {
if (mousehasmoved(e)) {
prevx=x;prevy=y;
p=e.getPoint();
x=p.getX();
y=p.getY();
g2 = (Graphics2D)image.getGraphics();
g2.setColor(Color.black);
g2.setXORMode(Color.white);
if ((x<=fixx) && (y>=fixy)) {
c1=x;c2=fixy;c3=fixx-x;c4=y-fixy;c5=prevx;c6=fixy;c7=fixx-prevx;c8=prevy-fixy;
else if ((x>=fixx)&&(y>=fixy)) {
c1=fixx;c2=fixy;c3=x-fixx;c4=y-fixy;c5=fixx;c6=fixy;c7=prevx-fixx;c8=prevy-fixy;
else if ((x>=fixx)&&(y<=fixy)) {
c1=fixx;c2=y;c3=x-fixx;c4=fixy-y;c5=fixx;c6=prevy;c7=prevx-fixx;c8=fixy-prevy;
else if ((x<=fixx)&&(y<=fixy)) {
c1=x;c2=y;c3=fixx-x;c4=fixy-y;c5=prevx;c6=prevy;c7=fixx-prevx;c8=fixy-prevy;
g2.draw(new  Rectangle2D.Double(c5,c6,c7,c8));
draw();
g2.draw(new  Rectangle2D.Double(c1,c2,c3,c4));
draw();
}public void mouseMoved(MouseEvent e)
p=e.getPoint();
x=p.getX();
y=p.getY();
main_window.setTitle("X- "+x+" "+"Y- "+y);
initx=x;inity=y; //Get me current position
if ((draw_mode==1)||(erase_mode==1)) {
//change_cursor();
else {
setCursor(Cursor.getDefaultCursor());
public void mousePressed(MouseEvent ex)
if ((draw_mode==0) && (erase_mode==0) &&((line_mode==1)||(box_mode==1))) {
fixx=ex.getX();fixy=ex.getY();
public void actionPerformed(ActionEvent ev)
Object ob=ev.getSource();
if (ob==b_draw) {
draw_mode=1;erase_mode=0;line_mode=0;
box_mode=0;
if (ob==b_erase) {
erase_mode=1;draw_mode=0;line_mode=0;
box_mode=0;
if (ob==b_line) {
erase_mode=0;draw_mode=0;line_mode=1;
box_mode=0;
if (ob==b_rec) {
erase_mode=0;draw_mode=0;line_mode=0;box_mode=1;
public static void main(String args[])
new FProf();
public boolean mousehasmoved (MouseEvent e)
return((initx != e.getX()) ||(inity!=e.getY()));
}}

Answer 1

change your mouseDragged method to something like:
    public void mouseDragged(MouseEvent e)
        Point p;
        if ((draw_mode == 1) || (erase_mode == 1))
            initx = x;
            inity = y;
            p = e.getPoint();
            x = p.getX();
            y = p.getY();
            draw();
        if ((line_mode == 1) && (box_mode == 0))
            if (mousehasmoved(e))
                prevx = x;
                prevy = y;
                p = e.getPoint();
                x = p.getX();
                y = p.getY();
                g2 = (Graphics2D) image.getGraphics();
                g2.setColor(Color.black);
                g2.setXORMode(Color.white);
                g2.draw(new Line2D.Double(fixx, fixy, prevx, prevy)); // erasing
                                                                        // previous
                                                                        // line
                draw();
                g2.draw(new Line2D.Double(fixx, fixy, x, y)); // redrawing
                                                                // newer one
                draw();
        if ((line_mode == 0) && (box_mode == 1))
            if (mousehasmoved(e))
                prevx = x;
                prevy = y;
                p = e.getPoint();
                x = p.getX();
                y = p.getY();
                g2 = (Graphics2D) image.getGraphics();
                g2.setColor(Color.black);
                g2.setXORMode(Color.white);
                 * calculate the former rectangle - it does not depend to
                 * the new rectangle!
                if((prevx <= fixx) && (prevy >= fixy))
                    c5 = prevx;
                    c6 = fixy;
                    c7 = fixx - prevx;
                    c8 = prevy - fixy;                   
                else
                    if ((prevx >= fixx) && (prevy >= fixy))
                        c5 = fixx;
                        c6 = fixy;
                        c7 = prevx - fixx;
                        c8 = prevy - fixy;
                    else
                        if ((prevx >= fixx) && (prevy <= fixy))
                            c5 = fixx;
                            c6 = prevy;
                            c7 = prevx - fixx;
                            c8 = fixy - prevy;
                        else
                            if ((prevx <= fixx) && (prevy <= fixy))
                                c5 = prevx;
                                c6 = prevy;
                                c7 = fixx - prevx;
                                c8 = fixy - prevy;
                 * calculate the new rectangle here
                if ((x <= fixx) && (y >= fixy))
                    c1 = x;
                    c2 = fixy;
                    c3 = fixx - x;
                    c4 = y - fixy;
                else
                    if ((x >= fixx) && (y >= fixy))
                        c1 = fixx;
                        c2 = fixy;
                        c3 = x - fixx;
                        c4 = y - fixy;
                    else
                        if ((x >= fixx) && (y <= fixy))
                            c1 = fixx;
                            c2 = y;
                            c3 = x - fixx;
                            c4 = fixy - y;
                        else
                            if ((x <= fixx) && (y <= fixy))
                                c1 = x;
                                c2 = y;
                                c3 = fixx - x;
                                c4 = fixy - y;
                g2.draw(new Rectangle2D.Double(c5, c6, c7, c8));
                draw();
                g2.draw(new Rectangle2D.Double(c1, c2, c3, c4));
                draw();
    }why?
You calculated the former rectangle in dependence to the newly created one. It does not depend on that, but needs its own if statements. I'm sure you will understand what I mean when looking at the method.