[Octave-bug-tracker] [bug #43907] OpenGL render code called even when gnuplot is graphics_toolkit

[Rik]

Follow-up Comment #16, bug #43907 (project octave):

@jwe: Your example doesn't specify a font so it uses '*' or whatever the
default is on your system.  On my system the default happens to have the
U+2205 glyph so no warning is produced.  That's why I had to specifically
switch to a font like Arial which lacks the empty set symbol.


text (0.5, 0.5, 'Hello \0 World', 'fontname', 'Arial')
warning: ft_render: skipping missing glyph for character '2205'
warning: called from
    text at line 148 column 12
warning: ft_render: skipping missing glyph for character '2205'


I think there is another bug report open somewhere about the difference
between Matlab and Octave with respect to symbolic characters.  Matlab uses
the Symbol font whenever it encounters one of the Tex sequences.  This has its
pros and cons.  On the pro side, the Symbol font includes the most commonly
used mathematical symbols and Adobe's Symbol font is one of those base fonts
that is almost always present; Printed output through Postscript will
therefore almost always work.  On the other hand, many fonts have a lot of the
symbols already.  For example, the Greek letters are always present.  It is
visually desirable to stay within a font family because the use of serifs will
match, the inter-character spacing will match, etc.  From our side, it is also
easier to code.  Otherwise, the calculation of text extents becomes a long
exercise where we would have to cycle over each fragment of the text and
calculate the extent given the particular font in place and then sum
everything at the end.  Right now we just set the font and the text and pass
it to FreeType to calculate the extent in one go.


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