Hello List, I'm using a large table with 12 columns in my application where users complained about slow scrolling performance when dragging the vertical scroll button.
I did some profiling using firebug and found following time consuming spots in the table implementation: 1) The BooleanDataCellRenderer which used a checkmark image to visualize the boolean state is slow (we have two columns in this table). Rendering the checked/unchecked image consumed a lot of time so I decided to write a boolean data cell renderer which uses a black circle utf-8 character (●) as a "true" mark. "false" is left blank. In order to allow setting the cell value via textNode.nodeValue, I inserted the character directly into the javascript sourcefile as a utf-8 character. Setting only the text node value is much faster then setting innerHTML. Entities must be set through innerHTML. The decision for the black circle was made because this character is supported by all browsers (the checkmark unicode character is not supported by IE). The soucecode can be downloaded from http://bugzilla.qooxdoo.org/attachment.cgi?id=132 2) The DefaultDataCellRenderer implementation is very costly regarding date and number formatting. Because formating was already done by our server backend, the solution to this was to write a data cell renderer which only assignes the cell html value. This cell renderer can be used for text only columns which do not need any localization and formating. The code of DirectDataCellRenderer.js can be downloaded from http://bugzilla.qooxdoo.org/attachment.cgi?id=133 3) The TablePaneScroller implementation fired a lot of time consuming setScrollLeft and setScrollTop method calls even if the values of left and top did not change. Because the mousemove event was attached to the pane scroller, which also includes the vertical scrollbar, the eventhandler was fired without a need. I splitted the mousemove, mouseup and mousedown eventhandlers for the pane and the header and attached them separately so no mouse move event is fired if the vertical scrollbutton is dragged. Aditionally I buffered the parameters of the scrollLeft ans scrollTop and did the calls only if the parameters changed. The patch against qooxdoo 0.6.6 can be downloaded from http://bugzilla.qooxdoo.org/attachment.cgi?id=131 In our case the scroll performace, especially the scrolling by dragging the vertical scroll bar is now three to five times faster compared to the performance before I did the optimizations. I've filed this as an enhancement bug in bugzilla.qooxdoo.org: http://bugzilla.qooxdoo.org/show_bug.cgi?id=330 -- Mit freundlichen Grüßen Dietrich Streifert -- Visionet GmbH Firmensitz: Am Weichselgarten 7, 91058 Erlangen Registergericht: Handelsregister Fürth, HRB 6573 Geschäftsführer: Stefan Lindner ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ qooxdoo-devel mailing list qooxdoo-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/qooxdoo-devel
