Re: Proposal: Saving graphs from Qt and wxt terminals

[Allin C. <cot...@wf...>]

On Fri, 24 Oct 2014, Philipp K. Janert wrote:

>> One thing to be careful of is the fact that saving to PDF (which is
>> certainly welcome in my opinion because the first word of PDF means
>> "portable") in the Qt terminal isn't using the PDF terminal.  There
>> are no colors in the PDF output via Qt, whereas the PDF terminal
>> creates a PDF output with colors.  Do we want as setup in which the
>> interactive terminals use the PDF terminal, or a setup in which the
>> interactive terminals use their own custom PDF output?
>
> I thought one could use the native APIs of the
> rendering library to handle the transformation
> to the desired graphics format (in the spirit
> of pngcairo and pdfcairo - both rendered, similarly,
> using the same lib). I think Qt can do that, too.

The cairo library can generate PDF, EPS, SVG or PNG at will, but only 
given a suitable abstract description of the plot. No library can 
transform a graphic from a bitmap format such as PNG to a "proper" vector 
representation.

Consider just fonts, for example: a proper vector file contains the 
specification of the fonts used so they can be reproduced at any 
resolution. A bitmap contains no real font information, just the pixels 
that compose the glyphs in the plot at a given, fixed resolution.

Allin Cottrell