SVG text alignment issue

SVG text alignment issue

[Thangalin via ntg-context]

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In the following example, the line and text should be aligned to the
middle  when LMTX converts the SVG figure using MP. (Note that you may have
to install Roboto, but the font isn't the issue.)

% SOF
\startbuffer[svg]
<svg
   width="25mm"
   height="70mm"
   viewBox="0 0 25 70"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <path
     d="m 12.500001,63.971412 v -12.4787"
     id="path2"
     style="fill:none;fill-opacity:1;stroke:#000000;stroke-opacity:1" />
  <text
     x="-48.831322"
     y="15.60547"
     id="text4933-8-6"
     transform="rotate(-90)"

 style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal"><tspan
       id="tspan159594-1"
       x="-48.831322"
       y="15.60547"

 style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal">16p13.3</tspan></text>
</svg>
\stopbuffer

\starttext
   \placefigure[]{}{\includesvgbuffer[svg][conversion=mp]}
\stoptext
% EOF

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Re: SVG text alignment issue

[Aditya Mahajan via ntg-context]

On Mon, 27 Jun 2022, Thangalin via ntg-context wrote:

> In the following example, the line and text should be aligned to the
> middle  when LMTX converts the SVG figure using MP. (Note that you may have
> to install Roboto, but the font isn't the issue.)
> 
> % SOF
> \startbuffer[svg]
> <svg
>    width="25mm"
>    height="70mm"
>    viewBox="0 0 25 70"
>    xmlns="http://www.w3.org/2000/svg"
>    xmlns:svg="http://www.w3.org/2000/svg">
>   <path
>      d="m 12.500001,63.971412 v -12.4787"
>      id="path2"
>      style="fill:none;fill-opacity:1;stroke:#000000;stroke-opacity:1" />
>   <text
>      x="-48.831322"
>      y="15.60547"
>      id="text4933-8-6"
>      transform="rotate(-90)"
> 
>  style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
> Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal"><tspan
>        id="tspan159594-1"
>        x="-48.831322"
>        y="15.60547"
> 
>  style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
> Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal">16p13.3</tspan></text>
> </svg>
> \stopbuffer
> 
> \starttext
>    \placefigure[]{}{\includesvgbuffer[svg][conversion=mp]}
> \stoptext
> % EOF

This has nothing to do with SVG. Looking at the definition of \includesvgbuffer, here is a simpler example illustrating the issue:

    \starttext
    \startplacefigure[location=here, title={Test}]
      \dontleavehmode\begingroup
      \startMPcode
        draw fullcircle scaled 2cm;
      \stopMPcode\endgroup
    \stopplacefigure
    \stoptext

One way to "fix" the alignment is to wrap everything in an hbox:


   \placefigure[]{}{\hbox{\includesvgbuffer[svg][conversion=mp]}}

Maybe there is a simple way to modify the definition of includesvgbuffer so that an \hbox is not needed.


Aditya


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Re: SVG text alignment issue

[Thangalin via ntg-context]

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Thanks Aditya,

I tried your suggestion, but the result is the same. Here's the XML setup
for all images in the document:

\startxmlsetups xml:img
  \starttexcode
    \placefloat[here,force]{}{%
      \hbox{\externalfigure[\xmlatt{#1}{src}][conversion=mp]}
    }
  \stoptexcode
\stopxmlsetups

Here's the Markdown source document:

![](dna-02)

The source document is automatically exported as XHTML:

<p>
      <img alt="" src="/path/to/images/dna-02.svg"/>
    </p>

The XHTML is then passed to ConTeXt, whereupon the XML setup for images is
applied. The result is the same: the alignment for the text is off. Here's
an example where you can see the issue on the 16q24.3 text (far right):

https://i.ibb.co/WGh03Sr/genes.png

When the same SVG file is rendered using Apache Batik, the white text is
aligned to the middle of the black box.

Are there aAny other work-arounds?

Thank you!

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Re: SVG text alignment issue

[Hans Hagen via ntg-context]

On 6/29/2022 4:35 AM, Aditya Mahajan via ntg-context wrote:
> On Mon, 27 Jun 2022, Thangalin via ntg-context wrote:
> 
>> In the following example, the line and text should be aligned to the
>> middle  when LMTX converts the SVG figure using MP. (Note that you may have
>> to install Roboto, but the font isn't the issue.)
>>
>> % SOF
>> \startbuffer[svg]
>> <svg
>>     width="25mm"
>>     height="70mm"
>>     viewBox="0 0 25 70"
>>     xmlns="http://www.w3.org/2000/svg"
>>     xmlns:svg="http://www.w3.org/2000/svg">
>>    <path
>>       d="m 12.500001,63.971412 v -12.4787"
>>       id="path2"
>>       style="fill:none;fill-opacity:1;stroke:#000000;stroke-opacity:1" />
>>    <text
>>       x="-48.831322"
>>       y="15.60547"
>>       id="text4933-8-6"
>>       transform="rotate(-90)"
>>
>>   style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
>> Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal"><tspan
>>         id="tspan159594-1"
>>         x="-48.831322"
>>         y="15.60547"
>>
>>   style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
>> Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal">16p13.3</tspan></text>
>> </svg>
>> \stopbuffer
>>
>> \starttext
>>     \placefigure[]{}{\includesvgbuffer[svg][conversion=mp]}
>> \stoptext
>> % EOF
> 
> This has nothing to do with SVG. Looking at the definition of \includesvgbuffer, here is a simpler example illustrating the issue:
> 
>      \starttext
>      \startplacefigure[location=here, title={Test}]
>        \dontleavehmode\begingroup
>        \startMPcode
>          draw fullcircle scaled 2cm;
>        \stopMPcode\endgroup
>      \stopplacefigure
>      \stoptext
> 
> One way to "fix" the alignment is to wrap everything in an hbox:
> 
> 
>     \placefigure[]{}{\hbox{\includesvgbuffer[svg][conversion=mp]}}
> 
> Maybe there is a simple way to modify the definition of includesvgbuffer so that an \hbox is not needed.
Thanks for checking it. Can you test with

\pushoverloadmode \unprotect

\permanent\tolerant\protected\def\includesvgfile[#1]#*[#2]%
   {\hbox\bgroup % no \dontleavehmode
    \getdummyparameters[\c!offset=\zeropoint,#2]%
    \clf_includesvgfile{#1}\dimexpr\dummyparameter\c!offset\relax
    \egroup}

\permanent\tolerant\protected\def\includesvgbuffer[#1]#*[#2]%
   {\hbox\bgroup % no \dontleavehmode
    \getdummyparameters[\c!offset=\zeropoint,#2]%
    \clf_includesvgbuffer{#1}\dimexpr\dummyparameter\c!offset\relax
    \egroup}

\protect \popoverloadmode

Hans



-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: SVG text alignment issue

[Thangalin via ntg-context]

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Thanks for checking this. Unfortunately, introducing \hbox didn't work; the
text is still off-center with respect to the vertical line:

https://i.ibb.co/hYGfdgZ/text-align.png

For comparison, the SVG file loaded into Inkscape appears similar to:

https://i.ibb.co/KF3PBkw/inkscape-alignment.png

Note how the text is vertically centered above the vertical line.

To me, it looks like the text, after a rotational transform, is being
written to the baseline rather than (cap height + descender height) / 2,
which seems to be a MetaPost conversion issue? There's another, possibly
related issue, which I'll provide in a separate thread.

Here's the code:

% SOF
\pushoverloadmode \unprotect

\permanent\tolerant\protected\def\includesvgfile[#1]#*[#2]%
   {\hbox\bgroup % no \dontleavehmode
    \getdummyparameters[\c!offset=\zeropoint,#2]%
    \clf_includesvgfile{#1}\dimexpr\dummyparameter\c!offset\relax
    \egroup}

\permanent\tolerant\protected\def\includesvgbuffer[#1]#*[#2]%
   {\hbox\bgroup % no \dontleavehmode
    \getdummyparameters[\c!offset=\zeropoint,#2]%
    \clf_includesvgbuffer{#1}\dimexpr\dummyparameter\c!offset\relax
    \egroup}

\protect \popoverloadmode

\startbuffer[svg]
<svg
   width="25mm"
   height="70mm"
   viewBox="0 0 25 70"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <path
     d="m 12.500001,63.971412 v -12.4787"
     id="path2"
     style="fill:none;fill-opacity:1;stroke:#000000;stroke-opacity:1" />
  <text
     x="-48.831322"
     y="15.60547"
     id="text4933-8-6"
     transform="rotate(-90)"

 style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal"><tspan
       id="tspan159594-1"
       x="-48.831322"
       y="15.60547"

 style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:12px;font-family:Roboto;-inkscape-font-specification:'Roboto,
Normal';font-variant-ligatures:normal;font-variant-caps:normal;font-variant-numeric:normal;font-variant-east-asian:normal">16p13.3</tspan></text>
</svg>
\stopbuffer

\starttext
   \placefigure[]{}{\includesvgbuffer[svg][conversion=mp]}
\stoptext
% EOF

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Re: SVG text alignment issue

[Hans Hagen via ntg-context]

On 6/29/2022 8:48 PM, Thangalin wrote:

> To me, it looks like the text, after a rotational transform, is being 
> written to the baseline rather than (cap height + descender height) / 2, 
> which seems to be a MetaPost conversion issue? There's another, possibly 
> related issue, which I'll provide in a separate thread.
Where is that rediculous (rather font version sensitive) rule defined? 
In all test i did so far baseline works ok.

Btw, it is sort of baffling what applications spit out when it comes to 
svg (and exp text). The cod being meant for machines "eyes" only is not 
really an excuse.

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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If your question is of interest to others as well, please add an entry to the Wiki!

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___________________________________________________________________________________

Re: SVG text alignment issue

[Thangalin via ntg-context]

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Here's the formal rule:

https://www.w3.org/TR/SVG11/coords.html#TransformAttribute

rotate(<rotate-angle> [<cx> <cy>]), which specifies a rotation by
<rotate-angle> degrees about a given point. If optional parameters <cx> and
<cy> are not supplied, the rotation is about the origin of the current user
coordinate system. The operation corresponds to the matrix [cos(a) sin(a)
-sin(a) cos(a) 0 0]. If optional parameters <cx> and <cy> are supplied, the
rotation is about the point (cx, cy). The operation represents the
equivalent of the following specification: translate(<cx>, <cy>)
rotate(<rotate-angle>) translate(-<cx>, -<cy>).

It looks like cx/cy, if not present, mean to rotate the text about its
origin, which I would take to be width/2 and height/2. They define the
rotation matrix as [cos(a) sin(a) -sin(a) cos(a) 0 0], where a is the angle:

https://www.w3.org/TR/SVG11/coords.html#RotationDefined

It appears as though LMTX is rotating around the baseline, rather than the
central point of the text's bounding box. (I thought that (cap height +
descender height) / 2 was the middle, but I suppose that wouldn't account
for diacritics.)

Thanks for looking into this!

On Wed, Jun 29, 2022 at 2:24 PM Hans Hagen via ntg-context <
ntg-context@ntg.nl> wrote:

> On 6/29/2022 8:48 PM, Thangalin wrote:
>
> > To me, it looks like the text, after a rotational transform, is being
> > written to the baseline rather than (cap height + descender height) / 2,
> > which seems to be a MetaPost conversion issue? There's another, possibly
> > related issue, which I'll provide in a separate thread.
> Where is that rediculous (rather font version sensitive) rule defined?
> In all test i did so far baseline works ok.
>
> Btw, it is sort of baffling what applications spit out when it comes to
> svg (and exp text). The cod being meant for machines "eyes" only is not
> really an excuse.
>
> Hans
>
>
> -----------------------------------------------------------------
>                                            Hans Hagen | PRAGMA ADE
>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to
> the Wiki!
>
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
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>
> ___________________________________________________________________________________
>

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