Hello,

Is there a way to get the width/height of svg images without creating
them as images first?

SVG files are just XML (text) files. Load one of the XML libraries and
read/parse the XML (I have a nifty SNIT class for that in my ModelRRSystem:
https://github.com/RobertPHeller/ModelRRSystem/blob/master/trunk/Scripts/Common/ParseXML.tcl).
In the <svg> tag are attributes for image size and coordinate space in use --
width, height, and viewBox.

At Wed, 22 Feb 2023 10:36:26 -0500 saitology9 <saitology9@gmail.com> wrote:

>
> Hello,
>
> Is there a way to get the width/height of svg images without creating
> them as images first?
>
>

--
Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software -- Custom Software Services
http://www.deepsoft.com/ -- Linux Administration Services
heller@deepsoft.com -- Webhosting Services

On 2/22/2023 11:27 AM, Robert Heller wrote:
> SVG files are just XML (text) files. Load one of the XML libraries and
> read/parse the XML (I have a nifty SNIT class for that in my ModelRRSystem:
> https://github.com/RobertPHeller/ModelRRSystem/blob/master/trunk/Scripts/Common/ParseXML.tcl).
> In the <svg> tag are attributes for image size and coordinate space in use --
> width, height, and viewBox.
>

Thank you. The width/height seem to be optional as some svg files don't
have them. I am not sure about the viewbox property.

Wouldn't a regexp be a better solution here?

saitology9 <saitology9@gmail.com> wrote:
> On 2/22/2023 11:27 AM, Robert Heller wrote:
>> SVG files are just XML (text) files. Load one of the XML libraries
>> and read/parse the XML (I have a nifty SNIT class for that in my
>> ModelRRSystem:
>> https://github.com/RobertPHeller/ModelRRSystem/blob/master/trunk/Scripts/Common/ParseXML.tcl).
>> In the <svg> tag are attributes for image size and coordinate space
>> in use -- width, height, and viewBox.
>>
>
> Thank you. The width/height seem to be optional as some svg files
> don't have them. I am not sure about the viewbox property.

Keep in mind that the notion of a width/height of an SVG is somewhat of
an odd question. The "S" in SVG stands for scalable and the "V" for
vector, and because they are scalable vectors, they can be any size you
want them to be. The only meaningful value for an SVG would be the
required aspect ratio to represent it without distortion.

Reality is many will indicate a "size" value in the xml, but that
should be taken more as a "suggestion" than a hard fact as such a size
would be for a bit-map graphic image.

> Wouldn't a regexp be a better solution here?

Not as a general XML parsing solution. Regular expressions are not
expressive enough to fully parse the entirety of the XML specification.

With that said, for a specific XML variant (i.e., SVG's) and for
looking for a very specific attribute therein (a suggested
width/height, should it exist) you /can/ use a regex and it should work
in most instances.

At Wed, 22 Feb 2023 15:24:42 -0500 saitology9 <saitology9@gmail.com> wrote:

>
> On 2/22/2023 11:27 AM, Robert Heller wrote:
> > SVG files are just XML (text) files. Load one of the XML libraries and
> > read/parse the XML (I have a nifty SNIT class for that in my ModelRRSystem:
> > https://github.com/RobertPHeller/ModelRRSystem/blob/master/trunk/Scripts/Common/ParseXML.tcl).
> > In the <svg> tag are attributes for image size and coordinate space in use --
> > width, height, and viewBox.
> >
>
> Thank you. The width/height seem to be optional as some svg files don't
> have them. I am not sure about the viewbox property.

The width/height propertiesare sometimes used to specific a *physical* size
(in inches or millimeters, etc.). The viewBox property can be used to specific
the coordinate bounding box, and thus the mapping of the coordinates in the
body of the file to "screen" (or paper or whatever) coordinates.

For example this Fritzing breadboard image:

<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: FritzingPartsSVGEditor 0.0.2 on x86_64-unknown-linux-gnu (BreadboardEditor) -->
<svg viewBox="0.000000 0.000000 47.565543 33.295880" width="4.756554mm" x="0mm" height="3.329588mm" y="0mm" version="1.1" xml:space="preserve">
<g id="breadboard">
<circle fpe:gid="1" cx="17.266292134831453" cy="16.647940074906355" r="16.0" fill="none" stroke="black" stroke-width="2.0"/>
<circle fpe:gid="2" id="connector1pin" cx="17.266292134831453" cy="16.64794007490637" r="4.999999999999999" fill="black"/>
<circle fpe:gid="3" id="connector2pin" cx="42.66629213483144" cy="16.64794007490637" r="4.9999999999999964" fill="black"/>
</g>
</svg>

defines a part that is "physically" 4.756554mm by 3.329588mm, with the
coordinates in tenths of a mm.

>
> Wouldn't a regexp be a better solution here?
>
>

--
Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software -- Custom Software Services
http://www.deepsoft.com/ -- Linux Administration Services
heller@deepsoft.com -- Webhosting Services

At Wed, 22 Feb 2023 20:40:05 -0000 (UTC) Rich <rich@example.invalid> wrote:

>
> saitology9 <saitology9@gmail.com> wrote:
> > On 2/22/2023 11:27 AM, Robert Heller wrote:
> >> SVG files are just XML (text) files. Load one of the XML libraries
> >> and read/parse the XML (I have a nifty SNIT class for that in my
> >> ModelRRSystem:
> >> https://github.com/RobertPHeller/ModelRRSystem/blob/master/trunk/Scripts/Common/ParseXML.tcl).
> >> In the <svg> tag are attributes for image size and coordinate space
> >> in use -- width, height, and viewBox.
> >>
> >
> > Thank you. The width/height seem to be optional as some svg files
> > don't have them. I am not sure about the viewbox property.
>
> Keep in mind that the notion of a width/height of an SVG is somewhat of
> an odd question. The "S" in SVG stands for scalable and the "V" for
> vector, and because they are scalable vectors, they can be any size you
> want them to be. The only meaningful value for an SVG would be the
> required aspect ratio to represent it without distortion.
>
> Reality is many will indicate a "size" value in the xml, but that
> should be taken more as a "suggestion" than a hard fact as such a size
> would be for a bit-map graphic image.
>
> > Wouldn't a regexp be a better solution here?
>
> Not as a general XML parsing solution. Regular expressions are not
> expressive enough to fully parse the entirety of the XML specification.
>
> With that said, for a specific XML variant (i.e., SVG's) and for
> looking for a very specific attribute therein (a suggested
> width/height, should it exist) you /can/ use a regex and it should work
> in most instances.

Tcl *does* have several XML parsing libraries, so it is not really to parse
things properly. If one is dealing with svgs from a variaty of sources,
using regexp is going to be hard to get working in all cases of legit SVG
files, since different programs will include (or not) the attributes one is
looking for in different places or order.

>
>

--
Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software -- Custom Software Services
http://www.deepsoft.com/ -- Linux Administration Services
heller@deepsoft.com -- Webhosting Services

On 2/22/2023 4:14 PM, Robert Heller wrote:
> At Wed, 22 Feb 2023 20:40:05 -0000 (UTC) Rich <rich@example.invalid> wrote:
>>
>> With that said, for a specific XML variant (i.e., SVG's) and for
>> looking for a very specific attribute therein (a suggested
>> width/height, should it exist) you /can/ use a regex and it should work
>> in most instances.
>
> Tcl *does* have several XML parsing libraries, so it is not really to parse
> things properly. If one is dealing with svgs from a variaty of sources,
> using regexp is going to be hard to get working in all cases of legit SVG
> files, since different programs will include (or not) the attributes one is
> looking for in different places or order.
>
>>
>>
>

Thank you both for the info. I knew about svg files but I hadn't worked
with them before. These are quite small svg image files so really either
option would work fine.