Re: FlowLayout and lightweight IDEs

bH <>
Sun, 17 Aug 2008 19:58:02 -0700 (PDT)
On Aug 9, 11:08 pm, bH <> wrote:

On Aug 9, 6:28 pm, "John B. Matthews" <nos...@nospam.invalid> wrote:

In article

 bH <> wrote:

On Aug 8, 2:44 pm, "John B. Matthews" <nos...@nospam.invalid> wrote=


In article <489c6ec2$0$4045$>,
 Knute Johnson <> wrote:

bH wrote:

This Q is about using a FlowLayout.

I compiled it and it displayed and ran. I don't use an IDE so =

I can't

help you there. It is possible that your problem is from not c=


the GUI on the EDT. And speaking of the EDT, you block it whil=


retrieving your image. Any change that would occur to the disp=


components will not happen until the EDT is freed. This may or=

 may not

cause you to lose some of your GUI but the GUI will not be able t=


respond until the image gathering code returns.

Knute's right about blocking. There's more here about perceived
performance when loading an image here:



Also, I'm suspicious of overriding the JFrame's paint() method
(inherited from Container), without calling super.paint():




Thanks for your responses. I have been unable to reconstruct the
program using panels. That rewrite of placing it on a panel makes non=


of the labels and textfields appear reagrdless of which IDE I use. Ye=


I did download John's sample above and it runs. but my adapting it to
my original one does not work. If I place the mouse over some of the
buttons they show up but nothing else shows up.

Yes, as documented: if I override paint in my code (above), I get the
same effect. If I call super.paint(), I don't:

  public void paint(Graphics g) { super.paint(g); ... }

Instead, just have your button set the imageLabel's icon to whatever
image you get back from the server and call repaint():

  public void actionPerformed(ActionEvent ae) {
    String cmd = ae.getActionCommand();
    if ("quit".equals(cmd)) {
    } else if ("grab".equals(cmd)) {
      try {
        ImageIcon icon = new ImageIcon(new URL(
          "<some valid chart url>"));
      } catch (MalformedURLException e) {

So I went back to my design written above with these revsions below.

Did you mean to post code below?

[...] This is not a good programming example, too quirky.

Or that it's too quirky to post?

John B. Matthews
trashgod at gmail dot com
home dot woh dot rr dot com slash jbmatthews- Hide quoted text -

- Show quoted text -

Hi John,
Your efforts are appreciated. Thanks for the reply. I have to study
this a while longer and do an acceptable revision that fully opens
with all three IDE's not just one. Since it happens with only one,
that is my defintion of quirky. I will post the code below.
bH- Hide quoted text -

- Show quoted text -

Hi All,
This is the corrected program fixing the errors
that I questioned about above. It is no longer
Andrew, I have tried to limit it to the correct text
width. With the fix and the notes in place, it is no longer
a small program. I also tried to take the suggestions
of others to make it happen.

The program:
/* demo taken from :
 With this program the user can adjust measures, colors
 when downloading a pentagon shape from Google.
 The Google Developers Guide site is:
import java.text.*;
import java.awt.image.*;
import java.util.Date;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.imageio.*;
import*; // For IOException

public class DrawImageCentered extends JFrame
  implements ActionListener {

  // Start up the application
  public static void main(String args[]) {
    DrawImageCentered app = new DrawImageCentered();
    app.setSize(800,500); //explicitly sets the size
    // app.pack(); // app.pack() makes the window
    // exactly the right size for its laid out contents
  } // main
  private BufferedImage image;

  private ClassLoader cl = getClass().getClassLoader();
   // So we can load image resources

  private JButton choice1 =
    new JButton("Google Draw Image"),
    choice2 = new JButton("Save Image"),
    choice3 = new JButton("Close");
  private JTextField addressField = new JTextField
    appendFieldcht = new JTextField("r"),
    appendFieldchs = new JTextField("400x400"),
    appendFieldchd = new JTextField("t:70,70,70,70,70,70"),
    appendFieldchm = new JTextField("B,FF0000,0,0,5"),
    appendFieldchf = new JTextField("c,s,000000");
  private JLabel lblhttp = new JLabel ("http:"),
    lblcht = new JLabel("cht:"),lblchs = new JLabel("chs:"),
    lblchd = new JLabel("chd:"),lblchm = new JLabel("chm:"),
    lblchf = new JLabel("chf:");

  private MyCanvas thePicture = new MyCanvas();
  // Widget for displaying the image

  // Constructor: lays out the display
  public DrawImageCentered() {
    Container contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout());
    contentPane.add(lblhttp); contentPane.add(addressField);
    contentPane.add(lblcht); contentPane.add(appendFieldcht);
    contentPane.add(lblchs); contentPane.add(appendFieldchs);
    contentPane.add(lblchd); contentPane.add(appendFieldchd);
    contentPane.add(lblchm); contentPane.add(appendFieldchm);
    contentPane.add(lblchf); contentPane.add(appendFieldchf);



  } // DrawImage constructor

  // actionPerformed: get picture to display and notify
  // the canvas
  public void actionPerformed(ActionEvent e) {

    if(e.getSource() == choice1){ // get image from google
      // address
      String urlGoogleDrw = addressField.getText()+"cht="+

      try {
        // Read from assembled URL
        URL url = new URL(urlGoogleDrw);
        image =;
      catch (IOException em) {
        System.out.println("import Data: I/O exception");
      ("Now press Save Image Button if you want to save it");

    } //choice 1
    if(e.getSource() == choice2){
      try {
        System.out.println("inside of Save it");
        Date dNow = new Date();
        SimpleDateFormat formatter = new SimpleDateFormat
        String df = new String(formatter.format(dNow));
        File file =
        new File("C:/Documents and Settings/bH/Desktop/"
           + df + " imageFromGoogle.png");
        ImageIO.write(image, "png", file);
        ("finished writing, see Desktop file");
      catch (IOException et) {
    } //choice 2
    if(e.getSource() == choice3){

    } //choice 3
  } // action draw picture

  /* Class MyCanvas: to display a chosen image.
   The image to be displayed is notified to this class by
   calling its setImage method.

   Constructor: only need to set up the size here,
   so the layout manager knows
  class MyCanvas extends Canvas {

    public MyCanvas() {
      // This let us see how big the canvas is!
    } // MyCanvas constructor

    private Image image; // The image on display just
    //now (nothing initially)

    // Set a new image to be displayed, and
    // refresh the canvas on-screen
    public void setImage(Image newImage) {
      image = newImage;
    } // setImage

    // And this actually draws the image, centered in
    // the canvas
    public void paint(Graphics g) {
      if (image != null) {
        // Make sure that there is an image
        int xOffset = (getWidth()-image.getWidth(this))/2;
        // x and y offsets to center the image in the
        // canvas
        int yOffset =
        g.drawImage(image, xOffset, yOffset, this);
        // Note: Coordinates relative to this Canvas widget
    } // paint
  } // class MyCanvas

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