SVG is not rendered for SVG Marker symbol

[pathmapper]

What is the bug or the crash?

SVG is not rendered/displayed for SVG Marker symbol.

Steps to reproduce the issue

Use the following SVG for an SVG Marker symbol -> no preview, nothing visible on the map canvas:

abstandsfl_rs.zip

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!--
  #%L
  xplan-workspaces - Modul zur Gruppierung aller Workspaces
  %%
  Copyright (C) 2008 - 2022 lat/lon GmbH, info@lat-lon.de, www.lat-lon.de
  %%
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU Affero General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU Affero General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  #L%
  -->

<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg
   xmlns:svg="http://www.w3.org/2000/svg"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   version="1.0"
   width="100%"
   height="100%"
   viewBox="-3 -3 100 100"
   id="svg2">
  <defs
     id="defs4">
    <style
       type="text/css"
       id="style6" />
    <symbol
       id="RsAbstandsflaeche"
       style="overflow:visible">
      <path
         d="M 0,0 L 0,-2"
         id="path9"
         style="fill:none;stroke:#000000;stroke-width:0.25" />
      <path
         d="M 0,-2.5 L 0.5,-1.5 L -0.5,-1.5 L 0,-2.5 z"
         id="path11"
         style="fill:#000000;stroke:none" />
    </symbol>
  </defs>
  <use
     transform="matrix(50.583447,0,0,40.21494,47,97.537347)"
     id="use13"
     x="0"
     y="0"
     width="6"
     height="6"
     xlink:href="#RsAbstandsflaeche" />
</svg>

Versions

QGIS version	3.27.0-Master	QGIS code revision	9c4d0a2
Qt version	5.15.3
Python version	3.10.4
GDAL/OGR version	3.4.1
PROJ version	8.2.1
EPSG Registry database version	v10.041 (2021-12-03)
GEOS version	3.10.2-CAPI-1.16.0
SQLite version	3.37.2
PostgreSQL client version	unknown
SpatiaLite version	5.0.1
QWT version	6.1.4
QScintilla2 version	2.11.6
OS version	Ubuntu 22.04.1 LTS
Active Python plugins
pluginbuilder3	3.2.1
sagaprovider	2.12.99
grassprovider	2.12.99
MetaSearch	0.3.6
processing	2.12.99
db_manager	0.1.20

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response

[troopa81]

There is an issue in Qt, I just opened a ticket : https://bugreports.qt.io/browse/QTBUG-106720

I don't know how to workaround this. If possible, don't use svg:symbol and svg:use together, but I fail to see how Inkscape deals with those item and how to prevent this.

I close the ticket, it needs a fix in Qt.

[pathmapper]

Thanks @troopa81 for looking into and reporting it to Qt 👍

I've got hundreds of these from a third party source. If someone knows a way how to automatically convert svg:symbol and svg:use to something else, I'd be happy to learn about. 😄

[troopa81]

@pathmapper Actually, it seems that the symbol tag is not part of the SVG tiny subset supported by Qt, and so QGIS.

So you have to convert from svg to svg tiny. There is this github project which propose to do the conversion https://github.com/manisandro/svg2svgt

Never tested it, hope it helps

[pathmapper]

https://github.com/manisandro/svg2svgt

Looks promising, I'll give it a try - thanks for the hint @troopa81.

[pathmapper]

svg2svgt just removes the symbol element instead of converting it:

Resulting file (not usable):

<?xml version="1.0"?>
<!-- Converted with SVG Converter - Version 0.9.6 (Compiled Thu Aug 31 
10:01:05 2017) - Copyright (C) 2011 Nokia -->
<svg xmlns="http://www.w3.org/2000/svg" viewBox="-3 -3 100 100" 
id="svg2" xmlns:xlink="http://www.w3.org/1999/xlink" baseProfile="tiny" 
version="1.0" width="100%" height="100%">
   <defs id="defs4"/>
   <use id="use13" 
transform="matrix(50.583447,0,0,40.21494,47,97.537347)" y="0" 
xlink:href="#RsAbstandsflaeche" width="6" x="0" height="6"/>
</svg>

---

But the <use> element is supported by SVG Tiny, and replacing <symbol> with <g> seems to work at least for the sample SVG provided above:

<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg
   xmlns:svg="http://www.w3.org/2000/svg"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   version="1.0"
   width="100%"
   height="100%"
   viewBox="-3 -3 100 100"
   id="svg2">
  <defs
     id="defs4">
    <style
       type="text/css"
       id="style6" />
    <g
       id="RsAbstandsflaeche"
       style="overflow:visible">
      <path
         d="M 0,0 L 0,-2"
         id="path9"
         style="fill:none;stroke:#000000;stroke-width:0.25" />
      <path
         d="M 0,-2.5 L 0.5,-1.5 L -0.5,-1.5 L 0,-2.5 z"
         id="path11"
         style="fill:#000000;stroke:none" />
    </g>
  </defs>
  <use
     transform="matrix(50.583447,0,0,40.21494,47,97.537347)"
     id="use13"
     x="0"
     y="0"
     width="6"
     height="6"
     xlink:href="#RsAbstandsflaeche" />
</svg>

[troopa81]

@pathmapper good to know, I was wondering what was the difference between symbol and g

[pathmapper]

@kraftto found a better way using the Inkscape CLI for removing the internal links and <symbol>-elements.

From kreis-viersen/xplan-reader#2 (comment):

inkscape --actions="select-all:all;object-unlink-clones;select-all:groups;object-to-path;export-plain-svg;vacuum-defs" --export-filename=<out-file> <in-file>

results in

<svg
   version="1.0"
   width="100%"
   height="100%"
   viewBox="-3 -3 100 100"
   id="svg2"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <defs
     id="defs4">
    <style
       type="text/css"
       id="style6" />
  </defs>
  <g
     id="use13"
     transform="matrix(50.583447,0,0,40.21494,47,97.537347)">
    <path
       d="M 0,0 V -2"
       id="path12"
       style="fill:none;stroke:#000000;stroke-width:0.25" />
    <path
       d="m 0,-2.5 0.5,1 h -1 z"
       id="path14"
       style="fill:#000000;stroke:none" />
  </g>
</svg>