Re: gnuplot graphics toolkit bugs

[Tatsuro MATSUOKA]

----- Original Message -----

> From: Daniel J Sebald 
> To: Tatsuro MATSUOKA 
> Cc: Maintainers List Octave 
> Date: 2015/6/25, Thu 10:36
> Subject: Re: gnuplot graphics toolkit bugs
> 
> On 06/24/2015 07:45 PM, Tatsuro MATSUOKA wrote:
>>  Probably this is a bad news for some unix platforms.
>> 
>>  from KNOWN ISSUES for gnuplot 5.0
>> 
>>  * Mouse double-click to export terminal coordinates to the X11 clipboard no 
> longer works reliably, and may be deprecated in the future.
> 
> I'll look into this.
> 
> 
>>  For gnuplot 5.0, x11 terminal is not a reliable one.
>>  Now recommended terminal is the wxt or the qt terminal.
> 
> That's a premature statement, in my opinion.  x11 terminal is 
> reliable--fallen out of favor would be more like it.  The reason that 
> statement 
> came about, I believe, is that wxt/qt have, let's say, more robust features 
> for images and aliasing.  This is true, but in some sense it is an 
> apples/oranges comparison.
> 
> 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.
> 
> As I see it, gnuplot qt terminal is a good default for Octave as it has the 
> same 
> look and feel because it is Qt-based and is robust as far as platforms go.  
> The 
> data crunchers/viewers may want to switch to wxt.  If wxt isn't available or 
> has some quirk, x11 works nearly as well and is as fast.
> 
> One advantage of x11 is that it is low level and does not involve OpenGL.  In 
> other words, any bugs in the OpenGL driver--which could be specific to one's 
> hardware setup--don't show up in gnuplot's x11 terminal.
> 
>> For gnuplot 5.0, x11 terminal is not a reliable one.


The choice of words "not a reliable one." was incorrect.
Sorry on this point.

However, I surprised when I found the description: 
"* Mouse double-click to export terminal coordinates to the X11 
clipboard no longer works reliably, and may be deprecated in the future."

I do not know reason why "Mouse double-click to export terminal coordinates 
to the X11 clipboard no longer works" happened 
but surprised that the statements "(it) may be deprecated in the future."  
The developers selected not to fix the issue but to kill the feature.
The important feature will be lost from X11 terminal.

As you know, configure in gnuplot 5, automatically enables qt terminal 
if qt development environments are available.
In addition, qt terminal is selected as a default terminal without any 
external setting like "export GNUTERM=wxt".
(On gnuplot 4, to enable qt, one should set option --with-qt at configure.)


This behavior can be understand from the description:

Part of RELEASE NOTES
 
NOTES TO PACKAGERS AND TESTERS
<snipped unrelated information>

 Configuration options for interactive use
        1. Qt The qt terminal supports interactive display with menu-driven 
output to png, svg or pdf. If either Qt4 or Qt5 is detected by the configure 
script, this will be the default terminal. It is now the fastest and most 
full-featured interactive terminal option.
To disable this terminal:
./configure --without-qt
To force use of Qt4 even if Qt5 is present:
./configure --with-qt=qt4
        2. Cairo/pango/wxWidgets This set of terminals includes
        * pngcairo, pdfcairo, epscairo, and cairolatex for output to a file
        * wxt for interactive display All of these will be built by default if 
the configuration script finds the required libcairo, libpango, libcairo, 
libwxgtk, and related support libraries To disable these terminals:
./configure --without-cairo ./configure --with-cairo --disable-wxt
        3. X11 (the "classic" interactive interface)
This used to be the preferred interactive interface, but the newer wxt and qt 
terminals offer nicer output and a wider range of features.
They clearly states that
  It is now the fastest and most full-featured interactive terminal option. 
(for qt)

I am using gnuplot mainly on windows and sometimes use it on Ubuntu.  
I select wxt terminal as a default terminal using startup file setting on both 
windows and Ubuntu.
Because it works both platforms. I do not select qt terminal because there 
sometimes reported bug fixes 
for qt terminal in the ChangeLog of development branch (Now 5.1).

 I some times provide windows binaries on gnuplot release. (e.g 4.6.6, 64 bit 
version of 5.0.0 and 5.0.1)
On window binaries for gnuplot ver. 5, qt terminal is available but not a 
default.
The default terminal is wxt.

I have only little experience for X11 terminal so the that I cannot understand 
how the developers behaviors 
affect X11 user for Unix based systems.

Tatsuro