Re: speed of qt terminal

[Daniel J S. <dan...@ie...>]

On 06/26/2015 06:49 PM, Tatsuro MATSUOKA wrote:
>
>
>> In other places Daniel state
>> ***************************************************************************************
>> For example, qt terminal uses QPixmap
>>
>> http://doc.qt.io/qt-5/qpixmap.html
>>
>> which is a feature of Qt to handle display of images.  However, this is
>> at a very high level in which image elements are treated individually,
>> not as a whole image.  Consequently, the user will find that the Qt
>> terminal can be rather slow for large data sets.  x11 is very low level,
>> so is much faster.  Yet, wxt is fast as well.
>> ***************************************************************************************
>>
>
>
> 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]

If you want, exit, re-launch and try

   cd '<buildpath>/gnuplot/demo'
   set term wxt
   splot 'blutux.rgb' binary array=(128,128) flipy format='%uchar' using 
1:2:3 with rgbimage

On my system there is a very large difference in redraw speed with Qt. 
Granted, it could be the data transfer that is slow and rendering is 
fast, don't know.  Also, on my system, the wxt terminal will show a bad 
aliasing bug when the image is rotated so that it is orthogonal to the 
window borders.

Dan