Hello,

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

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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 <[email protected]> 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
[email protected] -- Webhosting Services

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saitology9 <[email protected]> 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.

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At Wed, 22 Feb 2023 15:24:42 -0500 saitology9 <[email protected]> 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
[email protected] -- Webhosting Services

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

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?

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

At Wed, 22 Feb 2023 20:40:05 -0000 (UTC) Rich <[email protected]d> wrote:

saitology9 <[email protected]> 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
[email protected] -- Webhosting Services

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On 2/22/2023 4:14 PM, Robert Heller wrote:

At Wed, 22 Feb 2023 20:40:05 -0000 (UTC) Rich <[email protected]d> 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.

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