CODEWITHSUNDEEP
javaswinganimationjlabel
Michael SM
Michael SM

Reputation: 715

paint() does not get called in JLabel animation

I want to have a bubbling effect - some image with score bubbling from bottom to up. Below is the complete code. The problem is that paint() never gets called by repaint(). I am not good at java awt or swing. Any reason?

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.RenderingHints;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

  /**
   * The Bubble object for implementing some animations for each block of LOVE pieces
   */
    class Bubble extends JLabel {
        private static final long serialVersionUID = 1L;

        boolean  isBubbling = false;

        int xpos;
        int ypos;
        float transparency;
        String text = "+100";
        GameSettings config;

        AlphaComposite transparency05=AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);

        Bubble(int x, int y) {
            isBubbling=false;
            this.xpos = x;
            this.ypos = y;
        }

        void Bubbling() {
            isBubbling=true;
            for(int i=1;i<=50; i+=4) {
                System.out.println("Bubbling init");
              ypos -= (int)(7.2*i);
              transparency = transparency/2;
              setFont(new Font("arial, helvetica",Font.BOLD|Font.ITALIC,i));
              repaint();
              try {Thread.sleep(15);} catch(Throwable e) {}
            }

            new Thread() {
                public void run() {
                    for(int i=50;i>=0; i-=4) {
                        System.out.println("Bubbling run");
                      ypos -= (int)(7.2*i);
                      transparency = transparency/2;
                      setFont(new Font("arial, helvetica",Font.BOLD|Font.ITALIC,i));
                      repaint();
                      try {Thread.sleep(15);} catch(Throwable e) {}
                    }
                    isBubbling=false;
                    repaint();
                }
            }.start();
        }

        @Override
        public void paint(Graphics g1) {
            super.paint(g1);

            System.out.println("Bubbling paint begin");
            if(isBubbling) {
                System.out.println("Bubbling paint");

              Graphics2D  g=(Graphics2D) g1;
              g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

              FontMetrics fm=g.getFontMetrics();
              Rectangle r = getBounds();

              int width=fm.stringWidth(text);
              int height=fm.getHeight()*4/5;
              int cx=g.getFont().getSize()/10;
              int x=(r.width-width)/2;
              int xx=fm.charWidth('i');

              //g.setComposite(transparency05);
              g.setComposite(AlphaComposite.SrcOver);
              g.setColor(Color.red);
              //g.drawString(text,xpos*config.pieceWidth,ypos*config.pieceHeight);
              g.drawString(text,xpos,ypos);

              //Image img=Tetris.getResource().getImage(config.imagePath+config.imagePrefix+"heart"+config.imagePostfix);
              //g.drawImage(img,img.getWidth(null)+3,0,null);
              //g.drawImage(img,xpos*config.pieceWidth,ypos*config.pieceHeight,null);
            }
        }

        //for test
        static public void main(String[] args) {
            //Create and set up the window.
            JFrame frame = new JFrame("Demo");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            //Create and set up the content pane.
            JPanel newContentPane = new JPanel();
            newContentPane.setOpaque(true); //content panes must be opaque
            Bubble bub = new Bubble(50, 50);
            newContentPane.add(bub);

            frame.setContentPane(newContentPane);
            frame.setPreferredSize(new Dimension(300, 300));

            //Display the window.
            frame.pack();
            frame.setVisible(true);

            bub.Bubbling();
        }

    }

Upvotes: 3

Views: 398

Answers (2)

Guillaume Polet
Guillaume Polet

Reputation: 47637

There are many issues in your code, but the main reason why paint() is not invoked, is because your Bubble component has a size of 0 x 0. This is because you did not override getPreferredSize() to return an adequate value. Moreover, your ypos variable becomes negative in no time meaning that you don't have the time to see the animation.

Now, you should really consider taking care of the following other issues:

  • Override rather paintComponent than paint
  • Make sure that you never sleep on the EDT (here it does not happen because you are quite lucky)
  • Start your UI from the EDT with a SwingUtilities.invokeLater call.
  • Why do you create another thread in your Bubbling method remains a mistery to me (either do it from the start, for the entire method, or don't do it at all)
  • a javax.swing.Timer would be much more appropriate in your situation
  • Follow java naming conventions (methods start with a lower-case letter)

Here is an update of your code (but I did not changed everything according the remarks above):

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * The Bubble object for implementing some animations for each block of LOVE pieces
 */
class Bubble extends JLabel {
    private static final long serialVersionUID = 1L;

    boolean isBubbling = false;

    int xpos;
    int ypos;
    float transparency;
    String text = "+100";

    AlphaComposite transparency05 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);

    Bubble(int x, int y) {
        isBubbling = false;
        this.xpos = x;
        this.ypos = y;
    }

    void Bubbling() {
        isBubbling = true;
        for (int i = 1; i <= 50; i += 4) {
            System.out.println("Bubbling init");
            ypos--;
            transparency = transparency / 2;
            setFont(new Font("Arial", Font.BOLD | Font.ITALIC, i));
            repaint();
            try {
                Thread.sleep(50);
            } catch (Throwable e) {
            }
        }

        new Thread() {
            @Override
            public void run() {
                for (int i = 50; i >= 0; i -= 4) {
                    System.out.println("Bubbling run");
                    ypos--;
                    transparency = transparency / 2;
                    setFont(new Font("Arial", Font.BOLD | Font.ITALIC, i));
                    repaint();
                    try {
                        Thread.sleep(50);
                    } catch (Throwable e) {
                    }
                }
                isBubbling = false;
                repaint();
            }
        }.start();
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(180, 50);
    }

    @Override
    protected void paintComponent(Graphics g1) {
        super.paintComponent(g1);

        if (isBubbling) {
            System.out.println("Bubbling paint");

            Graphics2D g = (Graphics2D) g1;
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

            FontMetrics fm = g.getFontMetrics();
            Rectangle r = getBounds();

            int width = fm.stringWidth(text);
            int height = fm.getHeight() * 4 / 5;
            int cx = g.getFont().getSize() / 10;
            int x = (r.width - width) / 2;
            int xx = fm.charWidth('i');

            // g.setComposite(transparency05);
            // g.setComposite(AlphaComposite.SrcOver);
            g.setColor(Color.red);
            // g.drawString(text,xpos*config.pieceWidth,ypos*config.pieceHeight);
            System.err.println(xpos + " " + ypos);
            g.drawString(text, xpos, ypos);

            // Image img=Tetris.getResource().getImage(config.imagePath+config.imagePrefix+"heart"+config.imagePostfix);
            // g.drawImage(img,img.getWidth(null)+3,0,null);
            // g.drawImage(img,xpos*config.pieceWidth,ypos*config.pieceHeight,null);
        }
    }

    // for test
    static public void main(String[] args) {
        // Create and set up the window.
        JFrame frame = new JFrame("Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Create and set up the content pane.
        JPanel newContentPane = new JPanel(new FlowLayout());
        newContentPane.setOpaque(true); // content panes must be opaque
        Bubble bub = new Bubble(50, 50);
        newContentPane.add(bub);

        frame.setContentPane(newContentPane);
        frame.setPreferredSize(new Dimension(300, 300));

        // Display the window.
        frame.pack();
        frame.setVisible(true);

        bub.Bubbling();
    }

}

Upvotes: 4

nachokk
nachokk

Reputation: 14413

The problem is that your label no Dimension. You can set with setPreferredSize()

public static final Dimension PREF_SIZE = new Dimension(70, 70);
    //in main method or you can override `getPreferredSize()`   
    Bubble bub = new Bubble(50, 50);
    bub.setPreferredSize(PREF_SIZE);

Your are sleeping The Event Dispatch Thread. All gui stuff must be executed in that thread, instead of that take a look to Swing Timers.

Also you should override paintComponent() instead of paint() for swing components. Read more in this article

Upvotes: 1

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