Added scanline algorithm, a polygon filling algorithm used in computer graphics

Computer Graphics Algorithms/Clipping.java

@@ -0,0 +1,211 @@
+//line clipping with mouse interface
+package clipping;
+
+import java.util.ArrayList;
+import javax.swing.JFrame;
+import java.awt.*;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseListener;
+import java.util.Scanner;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class Clipping extends JFrame{
+
+    int prevX,prevY;
+    int count=0;
+    int state=0;
+    int noOfLines;
+    int xw,yw,width,height;
+    private int xMin,xMax,yMin,yMax;
+    private ArrayList<Line> lines=new ArrayList();
+
+    private static final int INSIDE=0;
+    private static final int TOP=8;
+    private static final int BOTTOM=4;
+    private static final int RIGHT=2;
+    private static final int LEFT=1;
+
+    @Override
+    public void paint(Graphics g){
+        Input(g);
+    }
+
+    public void drawWindow(Graphics g){
+        g.setColor(Color.red);
+        g.drawRect(xw,yw,width,height);
+        xMin=xw;
+        xMax=xw+width;
+        yMin=yw+height;
+        yMax=yw;
+        g.setColor(Color.BLACK);
+    }
+
+    public void Input(Graphics g){
+
+        Scanner sc=new Scanner(System.in);
+        System.out.println("Enter the coordinates of top left corner of window");
+        System.out.println("Enter x:");
+        xw=sc.nextInt();
+        System.out.println("Enter y:");
+        yw=sc.nextInt();
+        System.out.println("Enter the width: ");
+        width=sc.nextInt();
+        System.out.println("Enter the height:");
+        height=sc.nextInt();
+        drawWindow(g);
+        System.out.println("Enter the no of lines you want to clip");
+        noOfLines=sc.nextInt();
+        System.out.println("Draw the lines ");
+        addMouseListener(mouselistener);
+
+    }
+
+
+    private MouseListener mouselistener=new MouseListener() {
+        @Override
+        public void mouseClicked(MouseEvent e) {
+            int x=e.getXOnScreen();
+            int y=e.getYOnScreen();
+            Graphics g=getGraphics();
+
+            if(state==0){
+                prevX=x;
+                prevY=y;
+                state=1;
+            }
+            else{
+                lines.add(new Line(prevX,prevY,x,y));
+                g.drawLine(prevX, prevY, x, y);
+                 count++;
+                state=0;
+            }
+
+            if(count==noOfLines){
+                removeMouseListener(mouselistener);
+                try {
+                    Thread.sleep(5000);
+                } catch (InterruptedException ex) {
+                    Logger.getLogger(Clipping.class.getName()).log(Level.SEVERE, null, ex);
+                }
+                g.clearRect(0, 0, 800, 800);
+                output(g);
+            }
+        }
+
+        @Override
+        public void mousePressed(MouseEvent e) {
+        }
+
+        @Override
+        public void mouseReleased(MouseEvent e) {
+        }
+
+        @Override
+        public void mouseEntered(MouseEvent e) {
+        }
+
+        @Override
+        public void mouseExited(MouseEvent e) {
+        }
+    };
+
+    private int computeOutcode(int x,int y){
+        int outcode=INSIDE;
+
+
+        if(x < xMin)
+            outcode=outcode | LEFT;
+        else if(x > xMax)
+            outcode=outcode | RIGHT;
+        if(y < yMax)
+            outcode=outcode | TOP;
+        else if(y > yMin)
+            outcode=outcode | BOTTOM;
+        return outcode;
+
+    }
+
+    public void drawClippedLine(Graphics g,int x1,int y1,int x2,int y2){
+
+        int outcode1=computeOutcode(x1,y1);
+        int outcode2=computeOutcode(x2,y2);
+
+        while(true){
+
+            if((outcode1|outcode2)==0){
+                g.drawLine(x1, y1, x2, y2);
+                break;
+            }
+            else if((outcode1&outcode2)!=0)
+                break;
+            else{
+                int x,y;
+                int outcode;
+                if(outcode1!=0)
+                    outcode=outcode1;
+                else
+                    outcode=outcode2;
+
+                if((outcode&TOP)!=0){
+                    x=x1+(yMax-y1)*(x2-x1)/(y2-y1);
+                    y=yMax;
+                }
+                else if((outcode&BOTTOM)!=0){
+                    x=x1+(yMin-y1)*(x2-x1)/(y2-y1);
+                    y=yMin;
+                }
+                else if((outcode&RIGHT)!=0){
+                    y=y1+(xMax-x1)*(y2-y1)/(x2-x1);
+                    x=xMax;
+                }
+                else{
+                    y=y1+(xMin-x1)*(y2-y1)/(x2-x1);
+                    x=xMin;
+                }
+                if (outcode == outcode1) {
+                    x1 = x;
+                    y1 = y;
+                    outcode1 = computeOutcode(x1, y1);
+                } else {
+                    x2 = x;
+                    y2 = y;
+                    outcode2 = computeOutcode(x2, y2);
+                }
+            }
+
+        }
+
+    }
+
+
+    public void output(Graphics g){
+        drawWindow(g);
+      //  System.out.print(lines.size());
+        for(Line line:lines){
+         //   System.out.println(line.x1+"  "+line.y1+"  "+line.x2+"  "+line.y2);
+            drawClippedLine(g,line.x1,line.y1,line.x2,line.y2);
+        }
+    }
+    public static void main(String[] args) {
+       Clipping c=new Clipping();
+       c.setSize(800,800);
+       c.setVisible(true);
+       c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    }
+
+}
+
+
+class Line{
+
+int x1,y1,x2,y2;
+
+  Line(int x1,int y1, int x2, int y2){
+      this.x1=x1;
+      this.y1=y1;
+      this.x2=x2;
+      this.y2=y2;
+  }
+
+}