just started paint program. am i going the right direction?

[diggitydoggz]

Hey all. For practice, I am making a very very simple "paint" type program. The only features will be changeable color and different types of drawable shapes. The shape/line will then be created with one corner/end point at the spot where you clicked and the other following the mouse and changing in size/location as you move it and being formed when you click again, just like in paint.. Right now I have the GUI layout set up and I implemented an ActionEvent in the client. The actionPerformed method sends a different integer to the drawing pad (called PaintPanel) depending on which button I clicked on, which will then interpret it accordingly in the paintComponent method when I click/drag on the drawing area. Just posting it here to see if you veterans have any tips on my organization/coding... just a newbie here. Also if you think this will be a good way to do it.

Here's the client code:

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

public class Paint implements ActionListener {
  public static void main(String[] args) {
    Paint paint = new Paint();
  }
  
  JFrame frame = new JFrame();
  JPanel west = new JPanel(new GridLayout(9, 1));
  JButton color = new JButton("Color");
  JButton pencil = new JButton("Pencil");
  JButton line = new JButton("Line");
  JButton rect = new JButton("Rectangle");
  JButton ellipse = new JButton("Ellipse");
  JButton image = new JButton("Image");
  JButton eraser = new JButton("Eraser");
  PaintPanel pad = new PaintPanel();
  Color c;
  
  //Creates layout.
  public Paint() {
    frame.setTitle("HungSoft Paint");
    frame.setSize(new Dimension(500, 300));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new BorderLayout());
    
    pad.setPreferredSize(new Dimension(400, 300));
    pad.setBackground(Color.WHITE);
    
    west.setBackground(Color.GRAY);
    west.add(color);
    west.add(pencil);
    west.add(line);
    west.add(rect);
    west.add(ellipse);
    west.add(image);
    west.add(eraser);
    
    frame.add(west, BorderLayout.WEST);
    frame.add(pad, BorderLayout.CENTER);
    frame.pack();
    
    frame.setVisible(true);
  }
  
  
 //Tells the panel which tool to use.
  public void actionPerformed(ActionEvent e) {
    if(e.getSource() == pencil)
      pad.setTool(0);
    if(e.getSource() == line)
      pad.setTool(1);
    if(e.getSource() == rect)
      pad.setTool(2);
    if(e.getSource() == ellipse)
      pad.setTool(3);
    if(e.getSource() == image)
      pad.setTool(4);
    if(e.getSource() == eraser)
      pad.setTool(5);
  }
}

Here's the PaintPanel code:

import java.awt.*;
import javax.swing.*;

public class PaintPanel extends JPanel {
  private int tool;
  private Color c = Color.BLACK;
  
  //Will later put in if statements to choose tool based on the last selected tool, sent to the object through the setTool method.
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
  }
  
  public void setTool(int tool) {
    this.tool = tool;
  }
  
  public void setColor(Color c) {
    this.c = c;
  }
}

[diggitydoggz]

Also - does anybody have ideas on how I would be able to drag out shapes and not have them leave behind their marks on the pad? By this I mean the same way that you'd draw in microsoft paint. Like when you draw a line, you just click and the first endpoint is there and then the line just follows your pointer until you click again and then it is drawn in that spot. I don't have any idea of how I'd do this... just recently started learning about GUI's.

[hardwired]

Here's an idea about dragging shapes onto your drawing surface.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.AffineTransform;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;

public class DragOut extends JComponent {
    ShapePanel shapePanel = new ShapePanel(this);
    DropPanel dropPanel = new DropPanel();
    Shape shape;
    Point offset = new Point();

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        if(shape != null) {
            g2.setPaint(Color.red);
            g2.draw(shape);
        }
    }

    public void setShape(Shape shape, Point p) {
        this.shape = shape;
        Rectangle r = shape.getBounds();
        offset.x = p.x - r.x;
        offset.y = p.y - r.y;
        setVisible(true);
        repaint();
    }

    public void moveShape(Point p) {
        Rectangle r = shape.getBounds();
        double x = p.x - r.x - offset.x;
        double y = p.y - r.y - offset.y;
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);
        shape = at.createTransformedShape(shape);
        repaint();
    }

    public void dropShape(Point p) {
        Point xp = SwingUtilities.convertPoint(shapePanel, p, dropPanel);
        double x = xp.x - p.x;
        double y = xp.y - p.y;
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);
        dropPanel.add(at.createTransformedShape(shape));
        setVisible(false);
        repaint();
    }

    private JPanel getContent() {
        JPanel panel = new JPanel(new BorderLayout());
        panel.add(shapePanel, "Before");
        panel.add(dropPanel);
        return panel;
    }

    public static void main(String[] args) {
        DragOut test = new DragOut();
        test.setVisible(false);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setGlassPane(test);
        f.add(test.getContent());
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}

class ShapePanel extends JPanel {
    DragOut glassPane;
    Shape[] shapes;

    public ShapePanel(DragOut glassPane) {
        this.glassPane = glassPane;
        addMouseListener(ma);
        addMouseMotionListener(ma);
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        int w = getWidth();
        int h = getHeight();
        if(shapes == null) {
            int R = Math.min(w, h)/3;
            int[] sides = { 3, 5, 6 };
            shapes = new Shape[sides.length];
            for(int i = 0; i < shapes.length; i++) {
                int[][] xy = getPolygonArrays(w/2, (i+1)*h/4, R, sides[i]);
                shapes[i] = new Polygon(xy[0], xy[1], sides[i]);
            }
        }
        g2.setPaint(Color.red);
        g2.drawLine(w-1, 0, w-1, h-1);
        g2.setPaint(Color.blue);
        for(int i = 0; i < shapes.length; i++) {
            g2.draw(shapes[i]);
        }
    }

    public Dimension getPreferredSize() {
        return new Dimension(100,300);
    }

    private int[][] getPolygonArrays(int cx, int cy, int R, int sides) {
        int[] x = new int[sides];
        int[] y = new int[sides];
        double thetaInc = 2*Math.PI/sides;
        double theta = (sides % 2 == 0) ? thetaInc : -Math.PI/2;
        for(int j = 0; j < sides; j++) {
            x[j] = (int)(cx + R*Math.cos(theta));
            y[j] = (int)(cy + R*Math.sin(theta));
            theta += thetaInc;
        }
        return new int[][]{ x, y };
    }

    /** Use MouseInputAdapter for j2se 1.5- */
    private MouseAdapter ma = new MouseAdapter() {
        public void mousePressed(MouseEvent e) {
            Point p = e.getPoint();
            for(int i = 0; i < shapes.length; i++) {
                if(shapes[i].contains(p)) {
                    glassPane.setShape(shapes[i], p);
                    break;
                }
            }
        }

        public void mouseDragged(MouseEvent e) {
            glassPane.moveShape(e.getPoint());
        }

        public void mouseReleased(MouseEvent e) {
            glassPane.dropShape(e.getPoint());
        }
    };
}

class DropPanel extends JPanel {
    List<Shape> list = new ArrayList<Shape>();

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.green.darker());
        for(int i = 0; i < list.size(); i++) {
            g2.draw(list.get(i));
        }
    }

    public void add(Shape shape) {
        list.add(shape);
        repaint();
    }
}

[diggitydoggz]

holy crap. understanding that code is going to be a whole 'nother project on it's own (not because of the way it's written but because I'm new). thanks a bunch for making that though. i'm going to get started on trying to understand it.