Re: speed of qt terminal

[sfeam <sf...@us...>]

On Friday, 26 June 2015 09:13:03 PM Daniel J Sebald wrote:
> On 06/26/2015 08:36 PM, sfeam wrote:
> > On Friday, 26 June 2015 07:22:41 PM Daniel J Sebald wrote:
> >> On 06/26/2015 06:49 PM, Tatsuro MATSUOKA wrote:
> >
> >>> Daniel.
> >>> Can you show me a short script at which qt terminal is rather slow?
> >>>
> >>> I would like to execute it on windows and ubuntu PC.
> >>>
> >>> Tatsuro
> >>
> >> Try something like:
> >>
> >>     cd '<buildpath>/gnuplot/demo'
> >>     set term qt
> >>     splot 'blutux.rgb' binary array=(128,128) flipy format='%uchar' using
> >> 1:2:3 with rgbimage
> >>
> >>     [rotate the image using a mouse]
> >>
> >>     set term x11
> >>     replot
> >>
> >>     [rotate the image using a mouse]
> >
> > On my linux machine the qt terminal is much faster than x11 in this test.
> >
> >    qt5 5.2.0
> >    x11 xorg 1.14.5
> >    Intel on-chip HD Graphics 4000
> >
> > It is possible that your qt configuration is not using the optimal
> > rendering mode.  I'll look into trying to report this somewhere.
> > Maybe "show term"?
> >
> > 	Ethan
> 
> I'm pretty sure my system isn't optimum--based upon what I know from 
> compiling graphics drivers a few months back.  (It's a lot of work 
> because there are a half dozen or more supporting libraries that need to 
> be built until eventually the actual driver can be built.)  There's 
> probably some software rendering along the way and it eventually comes 
> back to X11.

I added a qDebug() statement to the terminal and it tells me:
Qt graphics platform:  "xcb" 

The Qt5 platforms are listed here:

	http://doc.qt.io/qt-5/qguiapplication.html

but it seems that Qt5 has deprecated the use of an environmental
variable to select among them.  I hadn't realized there was such
a large change from Qt4 -> Qt5, since it didn't require many
changes in our code.  The qt wiki says:

  QPA is the platform abstraction layer for Qt 5 and replaces QWS and the
  platform ports from Qt 4. [...]
  There is currently little documentation for QPA. The best approach for
  developing a new platform plugin is to look at the other plugins and
  see how they implement the APIs in question. The minimal plugin is a
  good starting point. The xcb, windows, cocoa, and qnx plugins are also
  actively developed and up to date.

> Intel hardware, on the other hand, has a lot of rendering support, so it 
> doesn't surprise me you're seeing the opposite performance-wise.  How 
> about wxt?  Does that terminal perform as well as qt?

wxt is slower than qt, and gtk3 is IMHO not ready for prime time.
At this point I would not recommend wxt. 

	Ethan