Re: Choppy refresh proble

  To: comp.lang.java.gui
On Jan 13, 2:54 pm, Daniel Gee <zef...@gmail.com> wrote:


paste.uni.cc/18083

Hmmm. That code was frustratingly close
to code that displays the problem (after
re-enabling the menu!).

Still - I was intrigued enough to continue
with it, and came up with this variant*.
I chose to:
- dump the JLabels for a direct 'paint()'
- lose the try/catch
- change the ActionListener for a KeyListener
- a number of other minor things I cannot recall.

* See how this works for you..
<sscce>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class JRSCE
  extends JFrame
  implements KeyListener
{
  static final int COLS = 80;
  static final int ROWS = 22;
  String[][] grid = new String[COLS][ROWS];

  int columnX = 3;
  int columnY = 3;

  /**
   * @param args none.
   */
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable() {
      public void run()
      {
        JRSCE thisClass = new JRSCE();
        thisClass.setDefaultCloseOperation(
          JFrame.EXIT_ON_CLOSE);
        thisClass.setVisible(true);
      }
    });
  }

  /**
   * build.
   */
  public JRSCE()
  {
    super("Use NUMPAD");

    GridPanel gp = new GridPanel();
    gp.addKeyListener(this);
    this.setContentPane(gp);
    pack();
    for (int y = 0 ; y < ROWS ; y++)
    {
      for (int x = 0 ; x < COLS ; x++)
      {
        grid[x][y] = ".";
      }
    }
    refresh();
  }

  public void keyReleased(KeyEvent ke) {}
  public void keyTyped(KeyEvent ke) {}
  public void keyPressed(KeyEvent ke) {
    switch ( ke.getKeyCode() )
    {
      case KeyEvent.VK_NUMPAD1:
        columnX--;
        columnY++;
        break;
      case KeyEvent.VK_NUMPAD2:
        columnY++;
        break;
      case KeyEvent.VK_NUMPAD3:
        columnX++;
        columnY++;
        break;
      case KeyEvent.VK_NUMPAD4:
        columnX--;
        break;
      case KeyEvent.VK_NUMPAD6:
        columnX++;
        break;
      case KeyEvent.VK_NUMPAD7:
        columnX--;
        columnY--;
        break;
      case KeyEvent.VK_NUMPAD8:
        columnY--;
        break;
      case KeyEvent.VK_NUMPAD9:
        columnX++;
        columnY--;
        break;
      default:
        System.err.println(
          "Use the numpad to walk! " +
          ke.getKeyCode() +
          " / " +
          ke.getKeyChar());
    }
    /**
     * Bounds check to not "walk off the screen"
     */
    columnX = Math.min(COLS - 1, columnX);
    columnY = Math.min(ROWS - 1, columnY);
    columnX = Math.max(0, columnX);
    columnY = Math.max(0, columnY);
    refresh();
    repaint();
  }

  /**
   * Refresh the screen after each STEP.
   */
  void refresh()
  {
    for (int y = 0 ; y < ROWS ; y++)
    {
      for (int x = 0 ; x < COLS ; x++)
      {
        if (columnX == x && columnY == y)
        {
          grid[x][y]="P";
        }
        else
        {
          grid[x][y]=".";
        }
      }
    }
  }

  class GridPanel extends JPanel {

    static final int STEP=10;

    GridPanel() {
      setFocusable(true);
    }

    /**
     * The displayed dgrid of labels.
     */
    public void paintComponent(Graphics g)
    {
      for (int y = 0 ; y < ROWS ; y++)
      {
        for (int x = 0 ; x < COLS ; x++)
        {
          g.drawString(
            grid[x][y],
            (x+1)*STEP,
            (y+1)*STEP );
        }
      }
    }

    public Dimension getPreferredSize() {
      return new Dimension(
        (COLS+1)*STEP,
        (ROWS+1)*STEP);
    }
  }
}
</sscce>

--
Andrew T.
PhySci.org

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