Mid-point Algorithm using j2me

File comment: Mid-point line

Mid-point-line.GIF [ 43.05 KiB | Viewed 7005 times ]

import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

/**
 *
 
 */
public class Line extends MIDlet implements CommandListener {
    Form form;
    TextField x1Field,x2Field,y1Field,y2Field;
    Command okCommand;
    myCanvas can;
    
    /** Creates a new instance of Line */
    public Line() {
        okCommand=new Command("OK",Command.OK,0);
        form=new Form("Enter The Cordinates");
        x1Field=new TextField("X1: ","",20,TextField.DECIMAL);
        y1Field=new TextField("Y1: ","",20,TextField.DECIMAL);
        x2Field=new TextField("X2: ","",20,TextField.DECIMAL);
        y2Field=new TextField("Y2: ","",20,TextField.DECIMAL);
        form.append(x1Field);
        form.append(y1Field);
        form.append(x2Field);
        form.append(y2Field);
        form.addCommand(okCommand);
        form.setCommandListener(this);
    }
    
    protected void startApp() throws MIDletStateChangeException {
        Display display=Display.getDisplay(this);
        display.setCurrent(form);
    }
    
    protected void pauseApp() {
    }
    
    protected void destroyApp(boolean b) throws MIDletStateChangeException {
    }
    
    public void commandAction(Command command, Displayable displayable) {
        if(command.getCommandType()==Command.OK) {
            
            int x1=Integer.parseInt(x1Field.getString());
            int y1=Integer.parseInt(y1Field.getString());
            int x2=Integer.parseInt(x2Field.getString());
            int y2=Integer.parseInt(y2Field.getString());
            can=new myCanvas(x1,y1,x2,y2);
            
            Display.getDisplay(this).setCurrent(can);
            can.repaint();
            
        }
    }
    
}
class myCanvas extends Canvas {
    public myCanvas(int x1,int y1,int x2,int y2) {
        this.x1=x1;
        this.y1=y1;
        this.x2=x2;
        this.y2=y2;
    }
    protected void paint(Graphics g) {
        g.fillRect(0,0,300,300);
        g.setColor(200,23,43);
        int x=0,y=0,dx=0,dy=0;
        int incE,incNE,p;
        float m = 0;

dx=x2-x1;
        dy=y2-y1;
        m=((float)dy/dx);
        System.out.println(m+"  "+dx+"  "+dy);
        
        if(m>=0&&m<=1&&dy>=0&&dx>0) {
            System.out.println("Case 1");
            p=dy*2-dx;
            incE=dy*2;
            incNE=(dy-dx)*2;
//////////////////////////////CASE 1///////////////////////////////////////
            y=y1;
            for(int i=x1;i<x2;i++) {
                g.drawLine(i+(100),(150)-y,i+(100),(150)-y);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    y++;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 2///////////////////////////////////////
        else if(m>1&&dy>=0&&dx>0) {
            System.out.println("Case 2");
            p=dx*2-dy;
            incE=dx*2;
            incNE=(dx-dy)*2;
            
            x=x1;
            for(int i=y1;i<y2;i++) {
                g.drawLine(x+(100),(150)-i,x+(100),(150)-i);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    x++;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 3///////////////////////////////////////
        else if(m<0&&m>=-1&&dx<0&&dy>0) {
            System.out.println("Case 3");
            p=dy*2-dx;
            incE=dy*2;
            incNE=(dy-dx)*2;
            
            y=y1;
            for(int i=x1;i>x2;i--) {
                g.drawLine(i+(100),(150)-y,i+(100),(150)-y);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    y++;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 4///////////////////////////////////////
        else if(m<-1&&dx<0&&dy>0) {
            System.out.println("Case 4");
            p=-dx*2-dy;
            incE=-dx*2;
            incNE=(-dx-dy)*2;
            
            x=x1;
            for(int i=y1;i<y2;i++) {
                g.drawLine(x+(100),(150)-i,x+(100),(150)-i);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    x--;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 5///////////////////////////////////////
        else if(m<0&&m>=-1&&dy<0&&dx>0) {
            System.out.println("Case 5");
            p=-dy*2-dx;
            incE=-dy*2;
            incNE=(-dy-dx)*2;
            
            y=y1;
            for(int i=x1;i<x2;i++) {
                g.drawLine(i+(100),(150)-y,i+(100),(150)-y);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    y--;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 6///////////////////////////////////////
        else if(m<-1&&dy<0&&dx>0) {
            System.out.println("Case 6");
            p=dx*2+dy;
            incE=dx*2;
            incNE=(dx+dy)*2;
            
            x=x1;
            for(int i=y1;i>y2;i--) {
                g.drawLine(x+(100),(150)-i,x+(100),(150)-i);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    x++;
                }
            }

g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 7///////////////////////////////////////
        else if(m>=0&&m<1&&dy<0&&dx<0) {
            System.out.println("Case 7");
            p=-dy*2+dx;
            incE=-dy*2;
            incNE=(-dy+dx)*2;
            
            y=y1;
            for(int i=x1;i>x2;i--) {
                g.drawLine(i+(100),(150)-y,i+(100),(150)-y);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    y--;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
//////////////////////////////CASE 8///////////////////////////////////////
        else if(m>1&&dy<0&&dx<0) {
            System.out.println("Case 8");
            p=-dx*2+dy;
            incE=-dx*2;
            incNE=(-dx+dy)*2;
            
            x=x1;
            for(int i=y1;i>y2;i--) {
                g.drawLine(x+(100),(150)-i,x+(100),(150)-i);
                if(p<=0) {
                    p=p+incE;
                } else {
                    p=p+incNE;
                    x--;
                }
            }
            
            g.drawLine(x2+(100),(150)-y,x2+(100),(150)-y);
        }
    }
    
    int x1=0;
    int x2=0;
    int y1=0;
    int y2=0;
    
}