Re: 5.2 rc2 tarball now available

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

On Tuesday, 04 July 2017 17:47:56 Daniel J Sebald wrote:
> On 07/04/2017 02:29 PM, Dmitri A. Sergatskov wrote:
> > On Tue, Jul 4, 2017 at 2:05 PM, sfeam <sf...@us...
> > <mailto:sf...@us...>> wrote:
> >
> >
> >     More to the point...  Is it only the "test" command that has a problem?
> >     If so I don't think we really care that much.  If boxed text in
> >     general is
> >     failing that would be a bigger issue.
> >
> >
> > ​Here is the output of a script;
> >
> > ​set label "1234567890" at 0,-0.4 boxed font "DejaVuSans, 5"
> > set label "1234567890" at 0,-0.2 boxed font "DejaVuSans, 7"
> > set label "1234567890" at 0,0 boxed font "DejaVuSans, 9"
> > set label "1234567890" at 0,0.2 boxed font "DejaVuSans, 12"
> > set label "1234567890" at 0,0.4 boxed font "DejaVuSans, 14"
> > set label "1234567890" at 0,0.6 boxed font "DejaVuSans, 18"
> > set label "1234567890" at 0,0.8 boxed font "DejaVuSans, 24"
> > plot sin(x)
> >
> > One can see that the problem is still there at very small (and perhaps
> > very large) font sizes.
> > ​The problem seems to be qt related. It looks fine reploted  to e.g.
> > pngcairo.
> 
> With a rudimentary browsing of the code, it doesn't seem to me that we 
> should expect the boxed text to be too accurate.  As for the test image, 
> it's
>  [snip]
> which is only a rough estimate at the font-processed string width in 
> pixels, assuming a constant-width character.  The test image code should 
> be placing a box similar to the way in with text/label items are placing 
> a box.

The code in "test" predates the boxed text option by many years.
It is, as you say, only a rough estimate.   It used to be the best we could do.
Now the boxed text option is a better alternative.

> But even in the case of labels with the "boxed" qualifier, I don't see 
> any mechanism for either feeding the string width from the terminal back 
> to gnuplot so that it can draw a box, 

Correct.  The core code gets no feedback from the terminals.
For many terminals it is impossible even in theory (e.g. PostScript).

> or specifying to the terminal that 
> it should put a box around the text it is requesting.  

Not correct.  The boxed text option works exactly by telling the terminal
it should put a box around the next block of text that is sent.
The terminal does this by itself with no additional help from any core routines.

[snip]

> Ethan, how well developed is the boxed label/text?  

There are additional options I would like to see added, but as to the
size of the bounding box  It should be perfect for the terminals that
support it at all.

> Is this something 
> that needs more development and better left for a next release?  Or 
> should a proper Qt fix be a simple matter?

For me the Qt output is perfect.  The bounding box of an object is a 
fundamental property in Qt.   If Dmitri's Qt version is getting it wrong,
I'd say that is a serious bug in Qt.  I found one bug report against
Qt 5.5.1 and 5.6beta that might be relevant, but the text bounding boxes
are fine on my machines with Qt 5.4.2 and 5.6.2

	Ethan



> Dan