Question

I am trying to build a an application where I intend to create some basic animations. My goal is to have a panel on top where the graphics will be painted and a panel below with regular buttons and labels.

I have done the code presented below but I am failing to draw rectangles inside previously drawn rectangles. I believe my problem is that I am calling a class (Rectangle) to draw the rectangles which extends a JPanel, meaning that everytime I try to draw a new rectangle a new panel will be creating not overlapping the previous one!

EDIT

I’ve looked up at some more examples, and finally could come up with a code to generate shapes (rectangles this case) as I need them on the same panel. I’ve made some changes to the code, below is the new code.

L.java

import java.awt.Color;
import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

class L extends JFrame {

public static final int ww = 1000;
public static final int wh = 600;
public static final String wt = "Teste";
Container pane = getContentPane();
DrawRectangle rectangle = new DrawRectangle();

public L() {
    setSize(ww,wh);
    this.setTitle(wt);
    Sim();
    pane.add(rectangle);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);
}

public void addRectangle(int px, int py, int pwh, Color pc) {
    this.rectangle.addRectangle( px, py, pwh, pc);
}

public void Sim() {
    addRectangle(100,100,250,Color.red);
    addRectangle(200,200,50,Color.green);
}

public static void main(String[] args) {

    L l = new L();

    try {
        UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
    } catch (UnsupportedLookAndFeelException ex) {
        ex.printStackTrace();
    } catch (IllegalAccessException ex) {
        ex.printStackTrace();
    } catch (InstantiationException ex) {
        ex.printStackTrace();
    } catch (ClassNotFoundException ex) {
        ex.printStackTrace();
    }

    //} 

}

}  

DrawRectangle.java

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.JPanel;

class DrawRectangle extends JPanel {
private java.util.List<Rectangle2D> squares;
private java.util.List<Color> colors;
//private int a, startX, startY;
public DrawRectangle(){
    squares = new ArrayList<Rectangle2D>();
    colors = new ArrayList<Color>();
}

public void addRectangle(int px, int py, int pwh, Color pc)  { // square
    squares.add( new Rectangle2D.Double(px, py, pwh, pwh) ) ;
    colors.add(pc);
    //this.a = a;
    //this.startX = startX;
    //this.startY = startY;
}
public void paintComponent(Graphics g) {
    Graphics2D g1 = (Graphics2D) g;
    for( Rectangle2D rect : squares ) {
        System.out.println(colors);
        g1.setColor(colors);
        g1.draw(rect);
    }
}
}

A new problem has now arose! What am I doing wrong that I can’t use the Color I am passing to the method to paint the shapes with different colors?

Answer 1

Hmm well maybe try creating a JPanel which accepts an array of Rectangles and then draw those too the panel like so:

import java.awt.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class RectangleDrawingTest extends JFrame {

    public RectangleDrawingTest() {
        createAndShowUI();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                RectangleDrawingTest drawingTest = new RectangleDrawingTest();
            }
        });
    }

    private void createAndShowUI() {
        setTitle("Rectangle Drawing Test");
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        setLocationRelativeTo(null);
        addComponentsToContentPane(this.getContentPane());
        setVisible(true);
    }

    private void addComponentsToContentPane(Container contentPane) {

        Rectangle[] recs = new Rectangle[3];
        recs[0] = new Rectangle(100, 100, 150, 100);
        recs[1] = new Rectangle(100, 100, 125, 75);
        recs[2] = new Rectangle(100, 100, 100, 50);

        MyPanel mr = new MyPanel(recs);

        contentPane.add(mr);
    }
}

class MyPanel extends JPanel {

    private final Rectangle[] recs;

    public MyPanel(Rectangle[] recs) {
        this.recs = recs;
    }

    @Override
    protected void paintComponent(Graphics grphcs) {
        super.paintComponent(grphcs);
        grphcs.setColor(Color.BLACK);
        for (int i = 0; i < recs.length; i++) {
            grphcs.drawRect(recs[i].x, recs[i].y, recs[i].width, recs[i].height);
        }
    }
}

Addendum:

Because you have both squares and color ArrayList transverse them using an for loop like this with a incrementing variable (squares size and color size are the same of course):

 for( int i=0;i<squares.size();i++) {
       // System.out.println(colors);
        g1.setColor(colors.get(i));
        g1.draw(squares.get(i));
    }