import java.awt.*;
import java.awt.image.*;
import java.awt.event.*; 
import java.awt.geom.*; 
import javax.imageio.*;
import javax.swing.*;
import java.io.*;

/**  BufferedImageDemo
  *
  *  Shows how to create & use a local BufferedImage
  *  Shows how to draw on it with low-level and high-level tools
  *  Shows how to save image using the local BufferedImage
  *
  *  M.Lampton (c) 2015 UCB SSL
  */
public class BufferedImageDemo
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowGUI();
            }
        });
    }
    
    private static void createAndShowGUI()
    {
        JFrame jf = new PlotFrame(); 
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setVisible(true);
    }
}



class PlotFrame extends JFrame
{
    public PlotFrame()
    {
        setTitle("BufferedImageDemo"); 
        setSize(400, 400); 
        final PlotPanel panel = new PlotPanel(); 
        Container contentPane = getContentPane(); 
        contentPane.add(panel); 

        JMenu fileMenu = new JMenu("File"); 
        fileMenu.add(new AbstractAction("Write PNG")
         {
            public void actionPerformed(ActionEvent event)
            {
                PlotPanel.bPNG = true;
                repaint(); 
            }
         });

        fileMenu.add(new AbstractAction("Exit")
         {
            public void actionPerformed(ActionEvent event)
            {
               System.exit(0);
            }
         });

        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);  
        menuBar.add(fileMenu);
    }
}


class PlotPanel extends JPanel
{
    static BufferedImage bi;       // local
    static Graphics2D g2bi;        // local
    static Graphics2D g2screen;    // from OS
    public static boolean bPNG = false; 

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g); 
        g2screen = (Graphics2D) g; 
        
        //---create a local bitmap---------
       
        int w = this.getWidth();    // local width
        int h = this.getHeight();   // local height
        System.out.println("W="+w+"   H="+h); 
        bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); 
        g2bi = bi.createGraphics(); 
        g2bi.setPaint(Color.WHITE);
        g2bi.fillRect(0, 0, w, h);  // Paints bitmap white. 

        //----get the artwork---------
        
        MyArt.doArt(bi); 

       //----blit the artwork to the screen------
       
       g2screen.drawImage(bi, 0, 0, null); 
       
       //---if requested, save the image--------
       
       if (bPNG)
       {
           try
           {
              ImageIO.write(bi, "png", new File("out.png")); 
              System.out.println("Image saved."); 
           }
           catch (Exception e)
           {
              System.out.println("Image could not be saved."); 
           }
       }
       bPNG = false; 
    }
}


/**  Artwork generator class demonstrates low-level and high-level tools.
  *  The Graphics2D context can be obtained from a BufferedImage,
  *  but a BufferedImage cannot be obtained from a Graphics2D context.
  *  To use both tools we need both the BufferedImage and the Graphics2D.
  *  So, communicate the BufferedImage to make both tools available.
  */
class MyArt
{
    static void doArt(BufferedImage bi)
    {
        int width = bi.getWidth(); 
        int height = bi.getHeight(); 
        
        //-----some low level bit work--------
        //-----draw ONLY legal pixels---------
        int icolor = new Color(255, 223, 105).getRGB(); 
        int radius = 166;
        int r2 = radius*radius; 
        int ihc = width/2;
        int ivc = height/2;
        for (int ih=0; ih<width; ih++)
           for (int iv=0; iv<height; iv++)
               if ((ih-ihc)*(ih-ihc) + (iv-ivc)*(iv-ivc) < r2)
                  bi.setRGB(ih, iv, icolor); 
               
        //----some high level artwork-----
        //----outside the box is OK-------
        Graphics2D g2 = bi.createGraphics(); 
        g2.setFont(new Font("Dialog", Font.BOLD, 12));
        g2.setPaint(Color.BLACK);
        g2.setStroke(new BasicStroke(1));    

        int iLeft=100, iRight=300, jTop= 100, jBot=300; 
        g2.setPaint(Color.BLACK); 
        g2.drawLine( iLeft,  jTop,  iRight,  jTop);
        g2.drawLine( iRight,  jTop,  iRight,  jBot);
        g2.drawLine( iRight,  jBot,  iLeft,  jBot);
        g2.drawLine( iLeft,  jBot,  iLeft,  jTop);
        String s = "Centered text"; 
        g2.drawString(s, (iLeft+iRight-getSWP(s,g2))/2, (jTop+jBot)/2); 
    }
    
    static int getSWP(String s, Graphics2D g2)
    // Gets string width in pixels with current font metrics
    // To get Rectangle2D, import java.awt.geom.*
    // Note: rounding a float returns an int.
    {
        FontMetrics fm = g2.getFontMetrics(); 
        Rectangle2D.Float r2f = (Rectangle2D.Float) fm.getStringBounds(s,g2);
        return Math.round(r2f.width);     
    }
}