Hi Hez, On Aug 22, 2009, at 11:04 PM, Hezekiah M. Carty wrote:
> For anyone interested, I have attached a patch for the Cairo plot > driver which speeds up plotting to the xcairo device considerably, > with the caveat that the plot contents will not appear in the plot > window until a flush occurs by one of: > > - A call to plflush > - The end of the page is reached (e.g., pleop, plenv to start a new > page, plend/plend1 to end the plot stream) I was just thinking about the same change to the wxWidget driver ;) > > This patch puts the behavior of the xcairo device somewhere between > the xwin driver which updates the plot display as it is made and the > qtwidget device which does not display the plot until the end of a > page. > > The rendering speedup is attained by rendering the plot to an > off-screen surface and only updating the visible window when > requested. With this patch applied, the PLplot examples render as > fast or faster on my system (64bit Linux, Cairo 1.8.6) with the xcairo > device as they do with the xwin device, without any flickering and > with all anti-aliasing enabled. Really faster then xwin? That would be quite unexpected. I would only believe that if cairo takes advantage of the graphics hardware. > > The compiled PLplot examples illustrate the speedup (particularly > examples 11, 16 and 20) and flicker-free rendering (example 17) quite > nicely. The shortcoming of not seeing the plot updates until a flush > becomes most noticeable when using the xcairo driver interactively, > say from an interactive Octave, OCaml or Python session. This lack of > interactive updates could be worked around with threading similar to > the pthread use in the xwin driver. The xwin threading code is quite > lengthy and complicated though, so this would likely be a fairly > significant task. In the moment for the wxWidgets driver I update the screen every 100 commands or so, which makes the driver slow - I actually believe that the xwin driver does something similar (at least I got the idea from there). We could introduce a command line option to set this parameter. If not set the driver waits for plfush() or pleop(), if set it updates every x plot commands. Otherwise I don't think it's so bad, that you need plflush(). It's an extra command, but on the other side it gives you full control as a user. I also intend introducing threading in the wxWidgets driver, but this is maybe simpler, since wxWidgets provides such functionality. > > I have been using this patch locally for about 6 months. I find it > makes the xcairo device much more useful for me. The speedup provided > by the off-screen rendering allows me to use the xcairo and its > improved rendering quality where I would have formerly used xwin due > to its impressive speed. > > All that said, I would like to ask for comments from others on this > patch before applying it to PLplot. I had asked a few other > developers for comments on a similar patch several months ago, with > the main concerns voiced at the time centering around the lack of > visible updates as a plot is made unless plflush is called or the plot > page ends. This is a significant visible change to how the xcairo > device works. I intended to bring the discussion of this on-list at > that time, but clearly this was delayed by a few months! I think it's okay, but maybe a command line option for setting the update rate would be great. We set it to a certain number, so that the average user will not see to much difference if the plot is updated every 100 commands. But it'll be faster which is always a good thing. Regards, Werner > > Hez > > -- > Hezekiah M. Carty > Graduate Research Assistant > University of Maryland > Department of Atmospheric and Oceanic Science > <cairo-xcairo-offscreen-rendering- > v2 > .patch > > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 > 30-Day > trial. Simplify your report design, integration and deployment - and > focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. > http://p.sf.net/sfu/bobj-july_______________________________________________ > Plplot-devel mailing list > Plplot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/plplot-devel -- Dr. Werner Smekal Institut fuer Allgemeine Physik Technische Universitaet Wien Wiedner Hauptstr 8-10 A-1040 Wien Austria DVR-Nr: 0005886 email: sme...@iap.tuwien.ac.at web: http://www.iap.tuwien.ac.at/~smekal phone: +43-(0)1-58801-13463 (office) +43-(0)1-58801-13469 (laboratory) fax: +43-(0)1-58801-13499 ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. 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