UTF-8: Is glyph available
lazarus / 31-LCL

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winni · 2019-10-20 13:14

Hi!

Searched in a lot of code amd in the net, but no reply.

Is there a function that tells me if a glyph for an UTF-8 codepoint in
a Font is available?
Something like

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
GlyphInFontAvailable (codepoint, fontname : string) : boolean;
Example:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i if
GlyphInFontAvailable('U+262E','Liberation sans') then ....
Even if someone knows a more complicated way - the answer is welcome.

Winni

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howardpc · 2019-10-20 15:31

I doubt that a reliable function of this sort could exist.
LowerCase("fontname") does not point to a single unambiguous entity,
even sometimes on a single OS, never mind across the plethora of
possible systems.
This is one reason many word processing file formats provide for
embedding of specific fonts, to prevent the "wrong" font of the same
name being used accidentally.
Also font foundries extend their fonts from time to time, and
continually introduce new ones such a function would not know about.
I suspect you will have to trawl through the font data for the fonts
you have available and discover this information, as it currently
exists for the fonts you have access to, for yourself.

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Thaddy · 2019-10-20 15:43

Comes to mind:
user schuler's excellent AI library would be able to recognize the
drawn glyph based on machine learning!
His library contains even an example how to implement such simple
recognition! And it works...
So you can draw that glyph and see if it matches a given reference
picture. In that case it is supported.
(This is doable! but complex)

But that is another matter. I partially agree with Howard in this
case. Such a function, a simple function relies on too many factors.
But note my remark: can be done.

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lucamar · 2019-10-20 16:39

I don't know whether this is useful but you could probably build your
own function using classes/functions from the FreeType units of
package LazUtils, like EasyLazFreeType, etc.

Drawback is that they are poorly documented if at all, though there
are some examples in the Lazarus folder.

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winni · 2019-10-20 18:01

Thanx markov & thaddy! I hoped you gave me another answer but that's
the situation.

In windows there are some routines in the gdi*.dll, which are used by
C++, Java and VBA. But that is win only.

@lucamar: Hihihi . I'm sitting here and read the freetype sources.
Ugly C-style Pascal. But thanx for the hint.

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sstvmaster · 2019-10-20 18:53

https://forum.lazarus.freepascal.org/index.php/topic,39102.msg267162.h
tml

see post from engkin.

maybe that will help?

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winni · 2019-10-20 21:27

Yeah! Unknown treasures in the fpc sources.

Thanx

Winni