<AWT Dev> <Swing Dev> Inefficiencies with custom TableCellRenderer and Applets

[Artem Ananiev]

Artem Ananiev wrote:
> Shannon Hickey wrote:
>> Clemens Eisserer wrote:
>>> Hi,
>>>
>>> I've created a library which has to use custom TableCellRenderers for
>>> its tables.
>>> I experienced a large performance difference between running my
>>> application as Application inside an JFrame and as an JApplet.
>>> Parented inside of the JFrame scrolling the table was smooth, however
>>> scrolling inside the applet was slow, especially if the mouse is over
>>> the table while scrolling.
>>>
>>> I did some profiling with netbeans-profiler and found the root-cause:
>>> BasicTableUI.paintCell->CellRendererPane.paintComponent->Container.validate->Component.updateCursorImmediatly->GlobalCursorManager.updateCursorImmediatly()->_updateCursor.... 
>>>
>>>
>>> The updateCursorImmediatly was called both times about 16.000 times,
>>> with JFrame it consumed 22% of the cycles which is already
>>> inefficient.
>>> As JApplet it calls into getLocationOnScreen() which calls down till
>>> XBaseWindow.toOtherWindow even slower which is about as slow as
>>> updating the Cursor itself, so as applet it consumes 48% of all EDT
>>> cycles.
> 
> What a sad story... I will file a bug against AWT about this problem.

The bug ID is 6706534 - it must be visible in the web in a couple of days.

Artem

>>> The DefaultTableCellRenderer simply overrides validate with an empty
>>> method, therefor no such calls are done.
>>> But why does CellRendererPane.paintComponent() call validate at all?
>>
>> CellRendererPain takes an argument that dictates whether or not it 
>> validates. In most cases it's told to validate by the caller since the 
>> renderer may need to do layout on its children.
>>
>> I suggest you override validate() on your custom renderer to do 
>> nothing, the same way the DefaultTableCellRenderer does.
>>
>>> If it cannot be avoided, is there no way to cache stuff in
>>> XBaseWindow.toOtherWindow at all?
> 
> We have some kind of caching for this call, however in the case of 
> applets (embedded frames) it doesn't work very well...
> 
> Artem
> 
>> You'll have to ask the AWT team about this. I've CC'd them.
>>
>> Shannon
>>
>>>
>>> Thanks, lg Clemens
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Very simple TableCellRenderer which triggers the slowness:
>>>       JLabel renderer = new JLabel();
>>>       public Component getTableCellRendererComponent(JTable table, 
>>> Object value,
>>>           boolean isSelected, boolean hasFocus, int row, int column) {
>>>          renderer.setText((String)value);
>>>          renderer.setOpaque(true);
>>>         return renderer;
>>>       }
>>