JScrollPane Scrolling Problem

Xavior2K3
Xavior2K3 used Ask the Experts™
on
Hi,

I have a very frustrating problem that i have been working on for several hours with no success. I basically want a panel on which i draw an image (using graphics.drawimage). I want to be able to zoom into the image (by making the panel bigger and drawing a bigger image on it), and when the image panel gets bigger than the window, scroll bars appear.

I have got this partially working, however when the panel is larger than the window and i try increasing the size even more, the scrollbars do not adjust to the new size. And also, when i reduce the size from very large (but still bigger than the window) the scroll bars do not change.

Im sorry if i havent explained myself very well!

Here's some sample code:

            CONSTUCTOR:
            .....
            JPanel imagePane = new JPanel;
            imagePane.parent = this;
            previewScroller = new JScrollPane(imagePane);
            .....

When i try to resize the image i do this:

            INSIDE THE JPANEL [imagePane]:
            .....
            this.setPreferredSize(new Dimension(newWidth(), newHeight()));
            repaint(); // calls a overridden paint method that draws an image onto the panel
            parent.previewScroller.revalidate(); // SHOULD sort out the scrollbars!
            ......

I'm really not sure why its not working! I hope someone can shed some light on this. If you need any more information just let me know.

Thanks, Mike
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Top Expert 2006
Commented:
revalidate() the imagePane after setPreferredSize
What is the class extending of w.r.t .setPreferredSize.
You must avoid to set a size for the component that you got a viewport of.
If the image grows, its component must grow to enclose it.
Apply:
        .pack();
on it.

;JOOP!

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