Create svg out of text
reddit / emacs

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haji-ali · 2022-09-26 08:58

I am trying to create an svg image out of a single character (to be
able to be able to rotate it). However, I can't quite get the svg to
perfectly replicate the text. Consider this code

    (let* ((char "A")
           (height (window-font-height))
           (svg (svg-create (window-font-width) height)))
      (svg-text svg char :x 0 :y (/ (window-font-height) 2))
      (insert-image (svg-image svg))
      (insert "\n")
      (insert char)
      (insert "\n"))

I expect this code to produce a two identical `A` characters: one as
an image and one as text. The result instead is as follows:

The image `A` is cut from the top and there is some padding which
leads to different line height compared to text `A`

​

https://preview.redd.it/jx1tdzvx36q91.png?width=47&format=png&auto=web
p&s=21b4a69876be1ac2c6fa10f1007b88737a9285f7

Am I doing something wrong? or is the result I am after can't be
achieved?

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itistheblurstoftimes · 2022-09-26 13:48

I messed around with the values for height and the :y offset and got
it closer to matching entered text but could not get it to match.
There are more arguments you can use with svg-text that might help
(e.g., :font-size (but I don't know what they all are)).

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haji-ali · 2022-09-26 13:57

Thanks. I also tried to mess around with these values with no luck. I
could change the size to make everything fit, but I really just want
the same size as normal text (ideally, the image should be
indistinguishable). There must be something that I don't understand
about the extra padding at the bottom.

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itistheblurstoftimes · 2022-09-26 14:06

Every time someone has produced an SVG package (e.g., orgmode display
tweaks, mode lines) I have had problems with displaying text. I fear
that even if there is a solution it is not going to be very portable.

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Nicolas-Rougier · 2022-09-26 14:12

You have to take ascent into account. Have a look at
https://github.com/rougier/svg-lib/blob/master/svg-lib.el#L274

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[deleted] · 2022-09-26 15:05

[deleted]

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haji-ali · 2022-09-26 20:32

Thanks! This seems to be the issue. Though on my system, I had to
divide the ascent of `font-info` by 10.
Also, any value for the `y` coordinate of the text seems to break when
the text is scaled.

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itistheblurstoftimes · 2022-09-28 03:23

Can you post the code? I am curious to get this working myself.

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Nicolas-Rougier · 2022-09-28 10:04

Scaling (inside or outside emacs) is not so simple. the svg-lib issues
are full of test to make it right but there's always a corner case
where it breaks.