plot issues -> favor pdfcairo [new changeset 2]

[Ben Abbott]

On Jun 9, 2009, at 9:26 AM, Benjamin Lindner wrote:

> Ben Abbott wrote:
>> On Jun 7, 2009, at 3:13 PM, Benjamin Lindner wrote:
>>> Ben Abbott wrote:
>>>> On Jun 6, 2009, at 10:38 AM, Ben Abbott wrote:
>>>>> On Jun 6, 2009, at 7:49 AM, Benjamin Lindner wrote:
>>>>>
>>>>>> Ben Abbott wrote:
>>>>>>> On Jun 5, 2009, at 4:08 PM, Ethan Merritt wrote:
>>>>>>>> On Friday 05 June 2009 11:12:52 Benjamin Lindner wrote:
>>>>>>>>> Ethan Merritt wrote:
>>>>>>>>>> On Friday 05 June 2009, Ben Abbott wrote:
>>>>>>>>>>
>>>>>>>>>>>>> Petr, what are the benefits of the pdfcairo and pngcairo  
>>>>>>>>>>>>> terminals
>>>>>>>>>>>>> over the pdf and png terminals?
>>>>>>>>>>
>>>>>>>>>> Aside from licensing issues for PDFLib, using cairo to  
>>>>>>>>>> generate the plots
>>>>>>>>>> allows antialiasing, transparency, and UTF-8 support.
>>>>>>>>>
>>>>>>>>> This may be a sutpid question, but what should a vector- 
>>>>>>>>> based graphics
>>>>>>>>> description support antialiasing for?
>>>>>>>>
>>>>>>>> Ben asked about both pdfcairo and pngcairo.
>>>>>>>> The anti-aliasing is an issue for png, not for pdf.
>>>>>>>> Conversely, the transparency support is an issue for pdf but  
>>>>>>>> not for png.
>>>>>>>>
>>>>>>>>> pdfcairo might be superior if you require transparency and  
>>>>>>>>> UTF-8,
>>>>>>>>> granted, but the quality of the generated output is  
>>>>>>>>> disappointing
>>>>>>>>> compared to pdf via postscript.
>>>>>>>>> I do a lot of image plots and found that the resulting file  
>>>>>>>>> sizes with
>>>>>>>>> the pdfcairo terminal are 4-8 times larger than a ps->pdf  
>>>>>>>>> output. Also
>>>>>>>>> you don't have good control over font selection, which is  
>>>>>>>>> IMO a
>>>>>>>>> knock-out criteria when doing high-quality plots for e.g.  
>>>>>>>>> latex inclusion.
>>>>>>>>
>>>>>>>> All I can say is that I have had the opposite experience.
>>>>>>>> Maybe that's because I work in a UTF environment and need  
>>>>>>>> support
>>>>>>>> for CJK character sets.  PostScript is basically hopeless for  
>>>>>>>> those.
>>>>>>>> There are some very fragile workarounds, but they are so  
>>>>>>>> installation-
>>>>>>>> specific that it doesn't work to build scripts or work flow  
>>>>>>>> around them.
>>>>>>>>
>>>>>>>> For latex inclusion, ps2pdf or direct PDF generation should  
>>>>>>>> be exactly
>>>>>>>> the same, and subject to the same limitations of whatever  
>>>>>>>> converted
>>>>>>>> Computer Modern fonts you are using.  If that is a primary  
>>>>>>>> concern,
>>>>>>>> then using one of the latex-based terminals directly is a  
>>>>>>>> better bet.
>>>>>>>>
>>>>>>>> Ethan
>>>>>>> It doesn't appear to me that there is one solution that is  
>>>>>>> preferred over the other in all cases.
>>>>>>> I'll propose the following, and encourage all to comment.
>>>>>>> -----------
>>>>>>> 1) if "pdfcairo" is present => use "set term pdfcairo ..."
>>>>>>> 2) if "pdf" is present => use "set term pdf ..."
>>>>>>> 3) if neither => use "set term postscript ..." and then  
>>>>>>> convert using ghostscript
>>>>>>> -----------
>>>>>>
>>>>>> Sounds very reasonable to me.
>>>>>>
>>>>>>> Although I'm a big LaTeX user, I elevated pdfcairo over pdf  
>>>>>>> for the transparency feature.
>>>>>>> Similarly for png
>>>>>>> -----------
>>>>>>> 1) if "pngcairo" is present => use "set term pngcairo ..."
>>>>>>> 2) if "png" is present => use "set term png ..."
>>>>>>> 3) if neither => use "set term postscript eps ..." and then  
>>>>>>> convert using ghostscript
>>>>>>> -----------
>>>>>>
>>>>>> same as above
>>>>>>
>>>>>>> For LaTeX, I will soon be adding support for the Lua/TikZ  
>>>>>>> terminal. Its rendering is a bit slow, but produces excellent  
>>>>>>> results for both latex and pdflatex.
>>>>>>> The solutions above will only work well for gnuplot 4.3+.  
>>>>>>> Prior to that the variable GPVAL_TERMINALS does not exist, and  
>>>>>>> octave has no manner to check for the existence of specific  
>>>>>>> terminals.
>>>>>>
>>>>>> For windows platform this is OK, since a working console  
>>>>>> application is only possible with 4.3+
>>>>>> Also interactive zooming with piped gnuplot works only with 4.3+
>>>>>>
>>>>>> benjamin
>>>>>
>>>>> Great!
>>>>>
>>>>> I've attached a changeset for the pdf part. It is combined with  
>>>>> a changeset for forcing mono rendering (there is some problem  
>>>>> with rgb2gray that has delayed me in pushing that change).
>>>>>
>>>>> In any event, I'd appreciated confirmation form linux and  
>>>>> window's users that this chageset works correctly.
>>>>>
>>>>> Ben
>>>> I've rolled up all the changesets for these plot issues. The  
>>>> attached must be applied to the current sources. With this change  
>>>> applied, the print command will favor the cairo terminals and  
>>>> will properly render a gray-scale image when the -mono option is  
>>>> specified.
>>>> I'd appreciate some testing to make sure there are no surprises.
>>>> I also  noticed we've been on bug list. I've moved this over to  
>>>> the maintainers list (I should have done that many emails ago).
>>>
>>> Hmm, I tried to import your changeset, but it fails for all hunks.
>>> My tip is 9305:52b4d82e5b4f from http://www.octave.org/hg/octave
>>>
>>> benjamin
>> I did find a problem with the prior changeset (new bug), but I  
>> don't understand why it wouldn't apply for you. In any event, try  
>> the attached version.
>
> Argh, stupid CRLF line endings mess.
> Got the changeset to apply.
> However, it does not work as expected.
>
> I have a gnuplot version, which has the pdfcairo and pngcairo  
> terminals and has the png terminal.
> Printing to pdf as "print -dpdf" now still invokes ghostscript.
> I believe I can guess where the problem is.
>
>      available_terminals = __gnuplot_get_var__ (gcf,  
> "GPVAL_TERMINALS");
>      available_terminals = regexp (available_terminals, "\\b\\w+\ 
> \b", "match");
>      gnuplot_supports_term = any (strcmp (available_terminals,  
> termn));
>
> This yields for the gnuplot under test a cell array  
> available_terminals which includes a terminal "pdfcairo" but does  
> *not* include a terminal "pdf". Thus a "print -dpdf" will yield  
> gnuplot_supports_term=false, and then the check for the cairo  
> terminals is never done.
>
> I guess the same will happen if gnuplot supports pngcairo but does  
> not support the png terminal.
>
> The decision logic is the wrong way round.
>
> benjamin

Please try the attached.

Ben

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