Question

Simple Painting GUI Apps

You are just developing the GUI app.

Your mission in this exercise is to implement a very simple Java painting application. Rapid Prototyping

The JFrame is an example that can support the following functions:

* Draw curves, specified by a mouse drag.

* Draw filled rectangles or ovals, specified by a mouse drag (don't worry about dynamically drawing the shape during the drag - just draw the final shape indicated).

* Shape selection (line, rectangle or oval) selected by a combo box OR menu.

* Color selection using radio buttons OR menu.

* Line thickness using a combo box OR menu.

* A CLEAR button.

Some other tips to get you started:

* Put import java.awt.*; and import java.awt.event.*; at the top of your java source.

* To find the mouse coordinates of a mouse event (e.g., a click), use the int getX() and int getY() methods on the MouseEvent object.

* Remember that getGraphics() returns a Graphics object that represents one set of drawing parameter settings for the JFrame (there is no global Graphics object!).

* Heres a code snippet to draw a blue dot at X=10, Y=100 on the JFrame:

Graphics G=getGraphics();

G.setColor(Color.BLUE);

G.drawRect(10,100,1,1);

* Here's the mouse dragged handler we wrote in class for a (lame) painting function on the JFrame:

private void myMouseDragged(java.awt.event.MouseEvent evt) {

int x=evt.getX();

int y=evt.getY();

java.awt.Graphics G=getGraphics();

G.drawRect(x, y, 1, 1);

}

* And another snippet to find out which item was selected from a combo box:

public void actionPerformed(ActionEvent e) {

JComboBox cb=(JComboBox)e.getSource();

String itemName=(String)cb.getSelectedItem();

}

Answer 1

//----------------- RapidPrototyping.java ----------------

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
//Class that paints according to the user wish.
public class RapidPrototyping extends JFrame implements MouseListener,ItemListener,ActionListener,MouseMotionListener {
  
   //panel to hold color,shapes and thickness components
   JPanel panel;
   //shapes combobox
   JComboBox shapes;
   //color radio buttons
   JRadioButton red, green, blue;
   //thickness combobox
   JComboBox thicknesses;
   //clear button.
   JButton clear;
   JPanel center;
  
   /*values of each selection*/
   Color color;
   int thickness;
   String shape;

   //start and end positions of mouse start and end positions of drag.
   int startX, startY;
   int endX, endY;
   boolean startSet;

   final String shapesList[] = { "RECTANGLE", "OVAL", "LINE" };

   final String thicknessesList[] = { "3", "6", "9", "12", "15" };

   RapidPrototyping() {
       //initialize values.
       setSize(600, 400);
       setLayout(new BorderLayout());

       panel = new JPanel(new FlowLayout());

       JLabel shapeLabel = new JLabel("Shape :");
       shapes = new JComboBox(shapesList);

       JLabel colorLabel = new JLabel("Color :");
       red = new JRadioButton("Red");
       green = new JRadioButton("Green");
       blue = new JRadioButton("Blue");
       ButtonGroup g = new ButtonGroup();
       g.add(red);
       g.add(blue);
       g.add(green);

       JLabel thicknessLabel = new JLabel("thickness :");
       thicknesses = new JComboBox(thicknessesList);

       clear = new JButton("Clear");
      
       center = new JPanel();
      
       //add elements to panel
       panel.add(shapeLabel);
       panel.add(shapes);
  
  
  
       panel.add(colorLabel);
       panel.add(red);
       panel.add(green);
       panel.add(blue);

       panel.add(thicknessLabel);
       panel.add(thicknesses);

       panel.add(clear);
       add(panel, BorderLayout.NORTH);
       add(center,BorderLayout.CENTER);
      
       /*Listeners*/
       addMouseListener(this);
       //adding mouse motionlistener is good but there is a drawback in that.
       //code will draw a shape without dragging.
       //it takes the previous point location and the curred dragged position.
       red.addItemListener(this);
       blue.addItemListener(this);
       green.addItemListener(this);
      
       shapes.addActionListener(this);
      
       clear.addActionListener(this);
      
       thicknesses.addActionListener(this);

       /* Default Values Setting */
       color = Color.RED;
       red.setSelected(true);
      
       thickness = 3;
       shape = "RECTANGLE";
       startSet = false;
      
      
   }
   //action listener
   public void actionPerformed(ActionEvent ae)
   {
       //set shape value on shapes selection changed.
       if(ae.getSource() == shapes)
       {
           shape = ""+shapes.getItemAt(shapes.getSelectedIndex());
       }
       //repaint the frame if clear button clicked.
       else if(ae.getSource() == clear)
       {
           repaint();
       }
       //change the thickness value.
       else if(ae.getSource() == thicknesses)
       {
           try
           {
               thickness = Integer.parseInt(""+thicknesses.getItemAt(thicknesses.getSelectedIndex()));
           }
           catch(Exception e)
           {
               thickness = 3;
           }
       }
   }
   //set color value according to the selection in color selectin of radio buttons.
   public void itemStateChanged(ItemEvent ie)
   {
       if(ie.getSource() == red)
       {
           color = Color.RED;
       }
       else if(ie.getSource() == blue)
       {
           color = Color.BLUE;
       }
       else if(ie.getSource() == green)
       {
           color = Color.GREEN;
       }
   }
   //mouse pressed is the first step in clicking mouse.
   //when a button is presesd this will invoke
   public void mousePressed(MouseEvent e)
   {
       //if the start point is not set
       if(startSet == false)
       {
           //then set start point as current mouse location
           startX = e.getX();
           startY = e.getY();
           startSet = true;
          
       }
   }

   // this function is invoked when the mouse is released
   public void mouseReleased(MouseEvent e)
   {
       //when mouse click is released .set end point.
       if(startSet)
       {
           endX = e.getX();
           endY = e.getY();
           startSet = false;
           //call drawShape() to draw current shape.
           drawShape();
          
       }
   }
   //when mouse is dragged in right to left or bottom to up
   //we have to change the start and end points for drawing rectangel and oval
   //because they take start position and width,height(not end position like line).
   public void checkAndSwap()
   {
       //swap value of x and y
       if(startX > endX)
       {
           int temp = startX;
           startX = endX;
           endX = temp;
       }
       if(startY > endY)
       {
           int temp = startY;
           startY = endY;
           endY = temp;
       }
   }
   //method drawShape() that draws current selected properties of paint
   //and draws them .
   public void drawShape()
   {
      
       //Graphics2D will be more useful than Graphics class.
       Graphics2D g2 = (Graphics2D) getGraphics();
       g2.setStroke(new BasicStroke(thickness));
       g2.setColor(color);
       //cal width and height
       int width = Math.abs(endX-startX);
       int height = Math.abs(endY-startY);
       System.out.println("\nThickness: "+thickness);
      
       //if shape is rectangle draw shape
       if(shape.equals(("RECTANGLE")))
       {
           //check and swap call only for rectangle and oval
           checkAndSwap();
           System.out.printf("Drawing %s : at -> %d %d with width and height %d,%d end point: %d %d\n",shape,startX,startY,width,height,endX,endY);
           //fillRect with following fields.
           g2.fillRect(startX,startY,width,height);
          
       }
       else if(shape.equals("OVAL"))
       {
           checkAndSwap();
           System.out.printf("Drawing %s : at -> %d %d with width and height %d,%d end point: %d %d\n",shape,startX,startY,width,height,endX,endY);
           g2.fillOval(startX,startY,width,height);
       }
       else
       {
           System.out.printf("Drawing %s : at -> %d %d end point: %d %d\n",shape,startX,startY,width,height,endX,endY);
           g2.drawLine(startX, startY, endX, endY);
       }
              
   }
   // this function is invoked when the mouse exits the component
   public void mouseExited(MouseEvent e)
   {

   }

   // this function is invoked when the mouse enters the component
   public void mouseEntered(MouseEvent e)
   {

   }

   // this function is invoked when the mouse is pressed or released
   public void mouseClicked(MouseEvent e)
   {
      
         
   }
   //MouseMotionListener methods are not used.
   public void mouseDragged(MouseEvent e)
   {
   }
   public void mouseMoved(MouseEvent e)
   {
   }
   //create jframe object and set its properties.
   public static void main(String[] args) {
       RapidPrototyping frame = new RapidPrototyping();
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
       frame.setResizable(false);
       frame.setTitle("Rapid Prototyping");
   }
}
//Sorry for the curve drawing. code will print all the shapes except.Curve drawing is big concept i //literally dont know about it.

//if you have any doubts please comment.

//output

//and drawing shapes will also be drawn at components shapes,radio buttons.it will remove when //clear button is pressed.