[Xpert] Changing the size of a JFrame dynamically

Discussion in 'Java' started by Pierre Vigneras, Jan 23, 2004.

  1. Hi,

    I've the following problem:

    two frames A and B are displayed, A is resizable whereas B is not. A
    contains a JPanel Pa (A.setContentPane(Pa)), and B a JPanel Pb
    (B.setContentpane(Pb)). Each JPanel contains no components, they are
    only used for painting.

    When the user resize A, I want to resize B as well to exactly the same
    size. So, I use the following code:

    Pa.addHierarchyBoundsListener(new HierarchyBoundsAdapter() {
    public void ancestorResized(HierarchyEvent e) {

    where resizeOtherFrame() is:

    void resizeOtherFrame() {


    Hence, when the user resize frame A with the mouse, the B frame is
    resized too. But the problem is that when Pb draws, it only draws on a
    portion of the region available. As if something between B and Pb has
    not been resized (maybe the RootPane?). Sun tutorial says that some
    LayoutManager does not use the size attribute (such as
    BorderLayout). But others do (BoxedLayout, SpringLayout). The problem
    is that my JPanel Pa and Pb does not have to layout something, hence
    they have a LayoutManager set to null! It is the JFrame wich must
    layout my JPanels (its content pane!). Maybe I must specify a
    LayoutManager such as SpringLayout (which uses the size attribute) to
    the JFrame B, but how?

    What is wrong ?

    Pierre Vigneras

    Distributed Objects Systems
    Pierre Vigneras, Jan 23, 2004
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  2. Pierre Vigneras

    Andrew Hobbs Guest

    LayoutManagers are only involved in laying out child Components. If you are
    only using the panels for painting then layout managers will not help you.

    How have you written the painting methods. If in absolute terms (eg
    g.drawLine(100, 100, 200, 200) you need to rewrite them in terms related to
    the size of the panel. That is you need to specify each position in a
    drawing method as a percentage of the panel height or width.

    eg g.drawLine(0.2 * getWidth(), 0.2 * getHeight(), 0.4 * getWidth(), 0.4 *

    Then as the panel changes size, the drawing expands or contracts to fit the



    Andrew Hobbs PhD

    MetaSense Pty Ltd - www.metasense.com.au
    12 Ashover Grove
    Carine W.A.
    Australia 6020

    61 8 9246 2026

    Andrew Hobbs, Jan 24, 2004
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