Custom LayoutManager troubles

[Sam Takoy]

Hi,

I've written a simple layout manager that's similar to BoxLayout excepts
deals with preferredSizes a little differently.

It all works well when use the mouse to expand the parent frame.
Everything gets re-laid out perfectly. However, when I shrink the frame,
my JPanel's stay their largest expanded size.

I monitor the layoutContainer() method and I notice that it gets called
on the contentPane, but not on any of its children. What's going on
here? Is this something that I control or is the system in charge of
calling layoutContainer()?

Many thanks in advance,

Sam

 

[Sam Takoy]

Hi,

I've written a simple layout manager that's similar to BoxLayout excepts
deals with preferredSizes a little differently.

It all works well when use the mouse to expand the parent frame.
Everything gets re-laid out perfectly. However, when I shrink the frame,
my JPanel's stay their largest expanded size.

I monitor the layoutContainer() method and I notice that it gets called
on the contentPane, but not on any of its children. What's going on
here? Is this something that I control or is the system in charge of
calling layoutContainer()?

Many thanks in advance,

Sam

If I may follow up - I guess even when I am expanding the window, I
don't understand what triggers the re-laying out of the children
components. Is there a place on the web where this is explained?

 

[John B. Matthews]

IIUC, your layout manager only manages the components in the Container
on which you call setLayout(). Nested Containers will each have their
own (possibly null) layout manager.

If I may follow up - I guess even when I am expanding the window, I
don't understand what triggers the re-laying out of the children
components.

Changing the size of your top-level Container would do it:

Is there a place on the web where this is explained?

See "How Layout Management Works":

<http://java.sun.com/docs/books/tutorial/uiswing/layout/howLayoutWorks.html>

 

[Dancing Fingers]

My experience is that not all LayoutManagers work together well,
particularly with a custom layout. You really have to experiment.
Chris

 

[markspace]

I monitor the layoutContainer() method and I notice that it gets called
on the contentPane, but not on any of its children. What's going on
here? Is this something that I control or is the system in charge of
calling layoutContainer()?

I'm not sure what you mean here. Could you post some code? I wrote a
custom layout as a test and it seems to all get called correctly, so I
don't know what your issue could be.

Here's my set up:

SwingUtilities.invokeLater( new Runnable() {

public void run()
{
JFrame frame = new JFrame( "Test" );
LayoutManager lm = new CustomLayout();
frame.setLayout( lm );
JPanel panel = new JPanel();
panel.add( new JButton("A") );
panel.add( new JButton("BBBBBBBBB") );
frame.add( panel );
frame.pack();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
} );