Question

The question I have is that I want to draw without having to drag and then clicking the button whether I want a line or rectangle. It should work first by hitting either the line or rectangle button and then making a drag on the panel with mouse, then after releasing the drag it creates the graphic.

Here is my current code.

package Mod1;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class paintGUI extends JComponent {

    // Image in which we're going to draw
    private Image image;
    // Graphics2D object ==> used to draw on
    private Graphics2D g2;
    // Mouse coordinates
    private int currentX, currentY, oldX, oldY;

    public paintGUI() {
        setDoubleBuffered(false);
        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                // save coord x,y when mouse is pressed
                oldX = e.getX();
                oldY = e.getY();
                System.out.println("Mouse pressed");
            }
        });

        addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent e) {
                System.out.println("Mouse dragged");

                // coord x,y when drag mouse
                currentX = e.getX();
                currentY = e.getY();
            }
        });
    }

    protected void paintComponent(Graphics g) {
        if (image == null) {
            // image to draw null ==> we create
            image = createImage(getSize().width, getSize().height);
            g2 = (Graphics2D) image.getGraphics();

            // clear draw area
            clear();
        }

        g.drawImage(image, 0, 0, null);
        repaint();
    }

    // now we create exposed methods
    public void clear() {
        g2.clearRect(0, 0, getSize().width, getSize().height);
        repaint();
    }

    public void thin() {
        g2.setStroke(new BasicStroke(3));
    }

    public void thick() {
        g2.setStroke(new BasicStroke(10));
    }

    public void red() {
        // apply red color on g2 context
        g2.setPaint(Color.red);
    }

    public void black() {
        g2.setPaint(Color.black);
    }

    public void magenta() {
        g2.setPaint(Color.magenta);
    }

    public void drawLine() {
        System.out.println("Drawing line");
        g2.drawLine(oldX, oldY, currentX, currentY);
        repaint();
    }

    public void drawRectangle() {
        System.out.println("Drawing rectangle");
        g2.drawRect(oldX, oldY, Math.abs(currentX - oldX), Math.abs(currentY - oldY));
        g2.fillRect(oldX, oldY, Math.abs(currentX - oldX), Math.abs(currentY - oldY));
        repaint();
    }

}

public class GUIPaint {

    JButton clearBtn, blackBtn, redBtn, magentaBtn, filledRectangleBtn, lineBtn, thinBtn, thickBtn;
    paintGUI paintGUI;
    ActionListener actionListener = new ActionListener() {

        public void actionPerformed(ActionEvent e) {
            if (e.getSource() == clearBtn) {
                paintGUI.clear();
            } else if (e.getSource() == thinBtn) {
                paintGUI.thin();
            } else if (e.getSource() == thickBtn) {
                paintGUI.thick();
            } else if (e.getSource() == blackBtn) {
                paintGUI.black();
            } else if (e.getSource() == redBtn) {
                paintGUI.red();
            } else if (e.getSource() == magentaBtn) {
                paintGUI.magenta();
            } else if (e.getSource() == filledRectangleBtn) {
                paintGUI.drawRectangle();
            } else if (e.getSource() == lineBtn) {
                paintGUI.drawLine();
            }
        }
    };

    public static void main(String[] args) {
        new GUIPaint().show();
    }

    public void show() {
        // create main frame
        JFrame frame = new JFrame("Swing Paint");
        Container content = frame.getContentPane();
        // set layout on content pane
        content.setLayout(new BorderLayout());
        // create draw area
        paintGUI = new paintGUI();

        // add to content pane
        content.add(paintGUI, BorderLayout.CENTER);

        // create controls to apply colors and call clear feature
        JPanel controls = new JPanel();

        clearBtn = new JButton("Clear");
        clearBtn.addActionListener(actionListener);
        blackBtn = new JButton("Black");
        blackBtn.addActionListener(actionListener);
        redBtn = new JButton("Red");
        redBtn.addActionListener(actionListener);
        magentaBtn = new JButton("Magenta");
        magentaBtn.addActionListener(actionListener);

        lineBtn = new JButton("Line");
        lineBtn.addActionListener(actionListener);
        filledRectangleBtn = new JButton("Filled Rectangle");
        filledRectangleBtn.addActionListener(actionListener);

        thickBtn = new JButton("Thick Line");
        thickBtn.addActionListener(actionListener);
        thinBtn = new JButton("Thin Line");
        thinBtn.addActionListener(actionListener);

        controls.add(lineBtn);
        controls.add(filledRectangleBtn);
        controls.add(thinBtn);
        controls.add(thickBtn);
        controls.add(blackBtn);
        controls.add(redBtn);
        controls.add(magentaBtn);
        controls.add(clearBtn);

        // add to content pane
        content.add(controls, BorderLayout.NORTH);

        frame.setSize(800, 800);
        // can close frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // show the swing paint result
        frame.setVisible(true);

    }

}

Answer 1

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

class paintGUI extends JComponent {

// Image in which we're going to draw
        private Image image;
// Graphics2D object ==> used to draw on
        private Graphics2D g2;
// Mouse coordinates
        private int currentX, currentY, oldX, oldY;
        
        private String shape = "line";

        public paintGUI() {
                setDoubleBuffered(false);
                addMouseListener(new MouseAdapter() {

                        public void mousePressed(MouseEvent e) {
                                // save coord x,y when mouse is pressed
                                oldX = e.getX();
                                oldY = e.getY();
                                System.out.println("Mouse pressed");
                        }
                        
                        public void mouseReleased(MouseEvent e) {
                                // save coord x,y when mouse is pressed
                                currentX = e.getX();
                                currentY = e.getY();
                                
                                if(shape.equals("line")) {
                                        drawLine();
                                } else if(shape.equals("rectangle")) {
                                        drawRectangle();
                                }
                        }
                });
        }

        protected void paintComponent(Graphics g) {
                if (image == null) {
                        // image to draw null ==> we create
                        image = createImage(getSize().width, getSize().height);
                        g2 = (Graphics2D) image.getGraphics();

                        // clear draw area
                        clear();
                        
                        thin();
                }

                g.drawImage(image, 0, 0, null);
                repaint();
        }

        // now we create exposed methods
        public void clear() {
                g2.clearRect(0, 0, getSize().width, getSize().height);
                repaint();
        }

        public void thin() {
                g2.setStroke(new BasicStroke(3));
        }

        public void thick() {
                g2.setStroke(new BasicStroke(10));
        }

        public void red() {
                // apply red color on g2 context
                g2.setPaint(Color.red);
        }

        public void black() {
                g2.setPaint(Color.black);
        }

        public void magenta() {
                g2.setPaint(Color.magenta);
        }
        
        public void setShape(String shape) {
                this.shape = shape;
        }
        
        public void drawLine() {
                g2.drawLine(oldX, oldY, currentX, currentY);
                repaint();
        }

        public void drawRectangle() {
                g2.drawRect(oldX, oldY, Math.abs(currentX - oldX), Math.abs(currentY - oldY));
                g2.fillRect(oldX, oldY, Math.abs(currentX - oldX), Math.abs(currentY - oldY));
                repaint();
        }

}

public class GUIPaint {

        JButton clearBtn, blackBtn, redBtn, magentaBtn, filledRectangleBtn, lineBtn, thinBtn, thickBtn;
        paintGUI paintGUI;
        ActionListener actionListener = new ActionListener() {

                public void actionPerformed(ActionEvent e) {
                        if (e.getSource() == clearBtn) {
                                paintGUI.clear();
                        } else if (e.getSource() == thinBtn) {
                                paintGUI.thin();
                        } else if (e.getSource() == thickBtn) {
                                paintGUI.thick();
                        } else if (e.getSource() == blackBtn) {
                                paintGUI.black();
                        } else if (e.getSource() == redBtn) {
                                paintGUI.red();
                        } else if (e.getSource() == magentaBtn) {
                                paintGUI.magenta();
                        } else if (e.getSource() == filledRectangleBtn) {
                                paintGUI.setShape("rectangle");
                        } else if (e.getSource() == lineBtn) {
                                paintGUI.setShape("line");
                        }
                }
        };

        public static void main(String[] args) {
                new GUIPaint().show();
        }

        public void show() {
                // create main frame
                JFrame frame = new JFrame("Swing Paint");
                Container content = frame.getContentPane();
                // set layout on content pane
                content.setLayout(new BorderLayout());
                // create draw area
                paintGUI = new paintGUI();

                // add to content pane
                content.add(paintGUI, BorderLayout.CENTER);

                // create controls to apply colors and call clear feature
                JPanel controls = new JPanel();

                clearBtn = new JButton("Clear");
                clearBtn.addActionListener(actionListener);
                blackBtn = new JButton("Black");
                blackBtn.addActionListener(actionListener);
                redBtn = new JButton("Red");
                redBtn.addActionListener(actionListener);
                magentaBtn = new JButton("Magenta");
                magentaBtn.addActionListener(actionListener);

                lineBtn = new JButton("Line");
                lineBtn.addActionListener(actionListener);
                filledRectangleBtn = new JButton("Filled Rectangle");
                filledRectangleBtn.addActionListener(actionListener);

                thickBtn = new JButton("Thick Line");
                thickBtn.addActionListener(actionListener);
                thinBtn = new JButton("Thin Line");
                thinBtn.addActionListener(actionListener);

                controls.add(lineBtn);
                controls.add(filledRectangleBtn);
                controls.add(thinBtn);
                controls.add(thickBtn);
                controls.add(blackBtn);
                controls.add(redBtn);
                controls.add(magentaBtn);
                controls.add(clearBtn);

                // add to content pane
                content.add(controls, BorderLayout.NORTH);

                frame.setSize(800, 800);
                // can close frame
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                // show the swing paint result
                frame.setVisible(true);

        }

}

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