Problem with doLayout() / validate() / invalidate()

Question

Hi, Java developers!!!
Ok, this is my current situation:
My application is as follows:
....................................Frame
...............................(BorderLayout)
.........................................|
................./----------------+-----------------\
................|.......................|.........................|
............NORTH:...............CENTER:..............SOUTH:
............Canvas.................Panel................TextField
.................................(BorderLayout)
.........................................|
.........................../---------+---------\
..........................|.............................|
....................CENTER:.......................EAST:
......................Panel..........................Panel
................(BorderLayout).............(BorderLayout)
........................|..................................|
.........|..............|............|..............|..............|
.....SOUTH:....CENTER:....EAST:......CENTER:......EAST:
....Scrollbar....Canvas....Scrollbar.....Canvas......Scrollbar
.(Horizontal)................(Vertical)........(X).......(Vertical)
The Canvas component marked as (X) has special code
that makes it's width resizable. In fact, what I did was:
public Dimension getPreferredSize()
Dimension sd;
Dimension cd;
sd = parentFrame.getSize();
cd = new Dimension(super.getPreferredSize());
cd.width = (int)(((double)sd.width) * widthPercent);
return cd;
Here, widthPercent is a global variable that indicates how
wide must be the component, related to the containing
frame's width.
When I change widthPercent, I do the following:
widthPercent = newWidthPercent;
invalidate();
repaint();
Well, it turns out that, when invoked, the component
does NOT change it's width immediately, but until the
next time I >resize< the Frame. I know the code above
is being executed, since the Frame is seen to be redrawing, but the layout does NOT change. I've tested
with almost everything I could:
doLayout();
validate(); invalidate();
getParent().doLayout();
getParent().validate(); getParent().invalidate();
parentFrame.doLayout();
parentFrame.validate(); parentFrame.invalidate();
etc. but it doesn't seem to work!!! No one changes the layout of the components until I resize the window!!!
Any ideas, please?
- Heriberto Delgado
([email protected])

Answer 1

Sorry for the long delay. I was just preparing the application for posting. The original one was somewhat large, with a lot of stuff that could hide the true problem. I narrowed it the most I could, while still showing the behavior I mentioned before. Here it is:
(The panel at the right is the resizable one. It's supposed to resize with the black stripe between the
right & left panels, which it does, but it shows up only until the window is resized.)
import java.awt.*;
import java.awt.event.*;
public class MainAppTest extends Frame
     class MapViewer extends Canvas
          public MapViewer()
               super();
               setBackground(Color.white);
     class SpriteViewer extends Canvas
          double widthPercent;
          Cursor resizeCursor;
          int initDraggedPosX;
          Frame parentFrame;
          public SpriteViewer(Frame newParentFrame)
               super();
               setBackground(Color.lightGray);
               setFont(new Font("SansSerif",Font.PLAIN,12));
               parentFrame = newParentFrame;
               widthPercent = 0.2;
               resizeCursor = Cursor.getPredefinedCursor(Cursor.W_RESIZE_CURSOR);
               enableEvents(MouseEvent.MOUSE_CLICKED |
               MouseEvent.MOUSE_MOVED |
               MouseEvent.MOUSE_DRAGGED);
          public void processMouseEvent(MouseEvent e)
               int i,m;
               super.processMouseEvent(e);
               switch(e.getID())
                    case MouseEvent.MOUSE_CLICKED:
                         if(e.getX() < 5)
                              initDraggedPosX = e.getX();
                         break;
          public void processMouseMotionEvent(MouseEvent e)
               Dimension fd;
               Dimension cd;
               Cursor newCursor;
               int newWidth;
               double newWidthPercent;
               super.processMouseMotionEvent(e);
               switch(e.getID())
                    case MouseEvent.MOUSE_MOVED:
                         if(e.getX() < 5)
                              newCursor = resizeCursor;
                         } else
                              newCursor = Cursor.getDefaultCursor();
                         if(!(newCursor.equals(getCursor())))
                              setCursor(newCursor);
                         break;
                    case MouseEvent.MOUSE_DRAGGED:
                         if(getCursor().equals(resizeCursor))
                              fd = parentFrame.getSize();
                              cd = getSize();
                              newWidth = cd.width + initDraggedPosX - e.getX();
                              if(fd.width!=0)
                                   newWidthPercent = ((double)newWidth)
                                   / ((double)fd.width);
                                   if(newWidthPercent<0.05)
                                        newWidthPercent = 0.05;
                                   if(newWidthPercent>0.9)
                                        newWidthPercent = 0.9;
                                   if(widthPercent != newWidthPercent)
                                        widthPercent = newWidthPercent;
                                        parentFrame.invalidate();
                                        parentFrame.validate();
                                        parentFrame.repaint();
                         break;
          public Dimension getPreferredSize()
               Dimension sd;
               Dimension cd;
               sd = parentFrame.getSize();
               cd = new Dimension(super.getPreferredSize());
               cd.width = (int)(((double)sd.width) * widthPercent);
               return cd;
          public void paint(Graphics g)
               Dimension cd;
               cd = getSize();
               g.setColor(Color.black);
               g.fillRect(0,0,
               5,cd.height - 1);
               g.setColor(Color.lightGray);
               g.fillRect(5,0,
               cd.width - 6,cd.height - 1);
     MapViewer CurrentMapViewer;
     Scrollbar HorizMapScrollbar;
     Scrollbar VertMapScrollbar;
     SpriteViewer CurrentSpriteViewer;
     Scrollbar VertSpriteScrollbar;
     Panel StatusBar;
     public MainAppTest(String[] args)
          super("Test");
          AppStart();
     public void AppStart()
          Class c;
          Panel p,p2,p3;
          Dimension sd;
          GridBagLayout gbl;
          GridBagConstraints gbc;
          TextField tf;
          setLayout(new BorderLayout(0,0));
          p = new Panel(new BorderLayout(0,0));
          CurrentMapViewer = new MapViewer();
          p.add(BorderLayout.CENTER,CurrentMapViewer);
          HorizMapScrollbar = new Scrollbar(Scrollbar.HORIZONTAL);
          p.add(BorderLayout.SOUTH,HorizMapScrollbar);
          VertMapScrollbar = new Scrollbar(Scrollbar.VERTICAL);
          p.add(BorderLayout.EAST,VertMapScrollbar);
          p2 = new Panel(new BorderLayout(0,0));
          CurrentSpriteViewer = new SpriteViewer(this);
          p2.add(BorderLayout.CENTER,CurrentSpriteViewer);
          VertSpriteScrollbar = new Scrollbar(Scrollbar.VERTICAL);
          p2.add(BorderLayout.EAST,VertSpriteScrollbar);
          p3 = new Panel(new BorderLayout(0,0));
          p3.add(BorderLayout.CENTER,p);
          p3.add(BorderLayout.EAST,p2);
          add(BorderLayout.CENTER,p3);
          StatusBar = new Panel();
          StatusBar.setBackground(Color.lightGray);
          gbl = new GridBagLayout();
          gbc = new GridBagConstraints();
          StatusBar.setLayout(gbl);
          gbc.weightx = 1;
          gbc.weighty = 1;
          gbc.insets = new Insets(0,0,0,0);
          gbc.fill = GridBagConstraints.BOTH;
          gbc.anchor = GridBagConstraints.CENTER;
          gbc.gridwidth = GridBagConstraints.REMAINDER;
          gbc.gridheight = 1;
          tf = new TextField();
          gbl.setConstraints(tf,gbc);
          StatusBar.add(tf);
          add(BorderLayout.SOUTH,StatusBar);
          addWindowListener
               new WindowAdapter()
                    public void windowClosing(WindowEvent e)
                         AppStop();
          pack();
          sd = getToolkit().getScreenSize();
          setSize(sd.width * 8 / 10, sd.height * 8 / 10);
          show();
          CurrentSpriteViewer.requestFocus();
     public void AppStop()
          System.exit(0);
     public static final void main(String[] args)
          new MainAppTest(args);