Re: Drawing electronic circuits or schematics with schemdraw Python package in a wxPython GUI

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On Thu, 25 Nov 2021 at 20:28, Dietmar Schwertberger <
[email protected]> wrote:

> On 25.11.2021 19:33, Matthias Brennwald wrote:
>
> I was thinking that a vector graphics format would be better in view of
> different (high) DPI environments. However, PNG (or other bitmap formats)
> are not necessarily out of question if there is no good way with vector
> graphics.
>
> That's only relevant if you want e.g. to zoom and edit or if Schemdraw
> does no good job in rendering into the image.
>
> If you want to zoom etc., i.e. you want to edit your schematics, then you
> should look into something else anyway.
>
Not sure what you mean here. Something else than wxPython? Something else
than SVG? Or something else?

> How could I make use of the PNG output from schemdraw in wxPython? The PNG
> examples I found for wxPython always make use of a PNG file as the source
> for the image data.
>
> Have a look at the "Using Images" section of the wxPython demo and also at
> the wxPython documentation.
>
The wxPython Demo is a bit tricky to get hold of, at least in my Linux
environment. The instructions at
https://wxpython.org/pages/downloads/index.html are a bit sketchy when it
comes to Linux.

That said, I managed to get the schemdraw PNG data to display in a wx
panel. I believe the trick is convert the schemdraw PNG data to a stream,
which can then feed into wx.ImageFromStream(...). I added a small
self-contained example below (code inspired by googling for examples by
others). I'd appreciate any thoughts on this.

-------------------------------------------------------
import wx
from io import BytesIO
import schemdraw
import schemdraw.elements as elm

class TestFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None)
        p = wx.Panel(self)
        fgs = wx.FlexGridSizer(cols=1)
        d = schemdraw.Drawing()
        d.add(elm.Resistor())
        d.add(elm.SourceV())
        data = d.get_imagedata('png')
        stream = BytesIO(data)
        img = wx.ImageFromStream(stream)
        sb = wx.StaticBitmap(p, -1, wx.BitmapFromImage(img))
        fgs.Add(sb)
        p.SetSizerAndFit(fgs)
        self.Fit()

app = wx.PySimpleApp()
frm = TestFrame()
frm.Show()
app.MainLoop()
-------------------------------------------------------


Why are you "stuck at 4.0"? It's not too hard to upgrade or to use project
> specific versions.
>

I like to write my code such that it works with the libraries available in
the standard software repositories of most systems. As far as I can tell,
many Linux distros have wxPython version 4.0. Version 4.1 seems to rely on
some stuff that is not considered stable/ready for inclusion in most
mainline distributions.

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<div dir=3D"ltr"><div dir=3D"ltr" class=3D"gmail_attr">On Thu, 25 Nov 2021 =
at 20:28, Dietmar Schwertberger &lt;<a href=3D"mailto:maillist@schwertberge=
r.de">[email protected]</a>&gt; wrote:<br></div><div class=3D"gmail=
_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex=
;border-left:1px solid rgb(204,204,204);padding-left:1ex">
 =20
   =20
 =20
  <div>
    <div>On 25.11.2021 19:33, Matthias Brennwald
      wrote:<br>
    </div>
    <blockquote type=3D"cite">
     =20
      <span style=3D"white-space:break-spaces">I was thinking that a vector=
 graphics format would be better in view of different (high) DPI environmen=
ts. However, PNG (or other bitmap formats) are not necessarily out of quest=
ion if there is no good way with vector graphics.</span></blockquote>
    <p>That&#39;s only relevant if you want e.g. to zoom and edit or if
      Schemdraw does no good job in rendering into the image.</p>
    <p>If you want to zoom etc., i.e. you want to edit your schematics,
      then you should look into something else anyway.<br></p></div></block=
quote><div>Not sure what you mean here. Something else than wxPython? Somet=
hing else than SVG? Or something else? <br></div><blockquote class=3D"gmail=
_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204=
,204);padding-left:1ex"><div><p>
    </p>
    <blockquote type=3D"cite">
      <div id=3D"gmail-m_-6392289052295859067geary-quote" dir=3D"auto">
        <div><span style=3D"white-space:break-spaces">How could I make use =
of the PNG output from schemdraw in wxPython? The PNG examples I found for =
wxPython always make use of a PNG file as the source for the image data.</s=
pan></div>
      </div>
    </blockquote>
    <p>Have a look at the &quot;Using Images&quot; section of the wxPython =
demo
      and also at the wxPython documentation.</p></div></blockquote><div>Th=
e wxPython Demo is a bit tricky to get hold of, at least in my Linux enviro=
nment. The instructions at <a href=3D"https://wxpython.org/pages/downloads/=
index.html">https://wxpython.org/pages/downloads/index.html</a> are a bit s=
ketchy when it comes to Linux.</div><div><br></div><div>That said, I manage=
d to get the schemdraw PNG data to display in a wx panel. I believe the tri=
ck is convert the schemdraw PNG data to a stream, which can then feed into =
wx.ImageFromStream(...). I added a small self-contained example below (code=
 inspired by googling for examples by others). I&#39;d appreciate any thoug=
hts on this.<br></div><div><br></div><div>---------------------------------=
----------------------<br></div><div>import wx<br>from io import BytesIO<br=
>import schemdraw<br>import schemdraw.elements as elm<br>=C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<br>class TestFrame(wx.Frame):<br>=C2=A0 =C2=
=A0 def __init__(self):<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 wx.Frame.__init__(se=
lf, None)<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 p =3D wx.Panel(self)<br>=C2=A0 =C2=
=A0 =C2=A0 =C2=A0 fgs =3D wx.FlexGridSizer(cols=3D1)<br>=C2=A0 =C2=A0 =C2=
=A0 =C2=A0 d =3D schemdraw.Drawing()<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 d.add(e=
lm.Resistor())<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 d.add(elm.SourceV())<br>=C2=
=A0 =C2=A0 =C2=A0 =C2=A0 data =3D d.get_imagedata(&#39;png&#39;)<br>=C2=A0 =
=C2=A0 =C2=A0 =C2=A0 stream =3D BytesIO(data)<br>=C2=A0 =C2=A0 =C2=A0 =C2=
=A0 img =3D wx.ImageFromStream(stream)<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 sb =
=3D wx.StaticBitmap(p, -1, wx.BitmapFromImage(img))<br>=C2=A0 =C2=A0 =C2=A0=
 =C2=A0 fgs.Add(sb)<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 p.SetSizerAndFit(fgs)<br=
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 self.Fit()<br><br>app =3D wx.PySimpleApp()<br>=
frm =3D TestFrame()<br>frm.Show()<br>app.MainLoop()</div><div><div>--------=
-----------------------------------------------<br></div></div><div><br></d=
iv><div><br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px=
 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>Wh=
y are you &quot;stuck at 4.0&quot;? It&#39;s not too hard to upgrade or to
      use project specific versions.<br></div></blockquote><div><br></div><=
div>I like to write my code such that it works with the libraries available=
 in the standard software repositories of most systems. As far as I can tel=
l, many Linux distros have wxPython version 4.0. Version 4.1 seems to rely =
on some stuff that is not considered stable/ready for inclusion in most mai=
nline distributions.</div></div></div>

<p></p>

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