Why does JTree scrolling too slow?

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Allen - 17 Jul 2006 02:28 GMT

I make a JTree with own TreeNode, TreeModel, TreeCellRenderer
definitions. And in the JTree
panel, it has a stamp painter which paints a logo image using
AlphaComposite. When I scroll
the tree with vertically, I feel it too slow because the scroll bar
moving not smoothly.

Pls help me to find the reason. Thank you.

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Chris Smith - 17 Jul 2006 03:12 GMT

> I make a JTree with own TreeNode, TreeModel, TreeCellRenderer
> definitions. And in the JTree
> panel, it has a stamp painter which paints a logo image using
> AlphaComposite. When I scroll
> the tree with vertically, I feel it too slow because the scroll bar
> moving not smoothly.

Well, painting with alpha-composites can certainly be slow. Any chance
you can do this work once and cache the results? If not, then you might
be stuck.

In any case, before going too much further, you should get some
profiling results. Do you have access to a profiler? Eclipse includes
a free one in the TPTP (Testing and Performance Tools Platform).

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Chris Smith - Lead Software Developer / Technical Trainer
MindIQ Corporation

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