jQuery in Action, 3rd edition
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Ben Buchli
Ranch Hand

Joined: Mar 26, 2004
Posts: 83
hi everybody,
I have a JFrame and added a JPanel to it, now how do I force shapes drawn to appear in this JPanel?
Thanks for the help!
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

  • Write a subclass of JPanel, and use that instead of JPanel itself.
  • In your subclass, override paintComponent(Graphics).
  • In the first line of your override, call super.paintComponent(Graphics).
  • Then draw your shapes.

  • [Jess in Action][AskingGoodQuestions]
    Ben Buchli
    Ranch Hand

    Joined: Mar 26, 2004
    Posts: 83
    Thanks, Ernest.
    It works...
    how would I find that out without help???
    now another question i have regarding panels. is it possible to add a ScrollPane to the Panel so that it becomes scrollable when the shapes are moved and not completely visible in the pane?
    how would i do that?
    thanks in advance
    [ May 04, 2004: Message edited by: Ben Buchli ]
    Eddie Vanda
    Ranch Hand

    Joined: Mar 18, 2003
    Posts: 281
    Instead of adding your subclassed JPanel to the JFrame's Container instance (from getContentPane), use it as the argument to constructing a new JScrollPane and then add that JScrollPane instance to your Container instance.
    So if your JPanel subclass is MyJPanel and the instance is myJPanel, then instead of using add (myJpanel), use:

    The nice thing about Standards is that there are so many to choose from!
    Ben Buchli
    Ranch Hand

    Joined: Mar 26, 2004
    Posts: 83
    Thanks, Eddie, thats what I did.
    However, the problem is that when the shape gets drawn outside of the viewing window (which means it's not or only partially visible) then I want to have scroll bars available for the user to scroll.
    How do I do that?? I have the scrollbars, but somehow, they stay disabled...
    Craig Wood
    Ranch Hand

    Joined: Jan 14, 2004
    Posts: 1535
    The idea is to override getPreferredSize in our drawing component and to keep it apprised of the changing width and height requirements during the drawing. As we update the width and height fields we call revalidate on the drawing component which tells the scrollpane we need more space.
    Here's an example:
    Ben Buchli
    Ranch Hand

    Joined: Mar 26, 2004
    Posts: 83
    Thanks a lot Craig,
    seems to work...
    I agree. Here's the link: http://aspose.com/file-tools
    subject: JFrame
    It's not a secret anymore!