How do I draw a semicircle?

[Phil]

Thank you for reading this.

I'm trying to create an analogue meter. So far I have a pointer that
moves and now I'm trying to create a dial face. Just for the sake of
simplicity, the dial face is a semicircle.

I've spent a lot of time experimenting and searching for an answer
without success. The following is based on something that I found, it
runs but doesn't draw anything:

    def OnPaint(self, e):

        #pdc = wx.PaintDC(self)
        #gc = wx.GCDC(pdc)

        gc = wx.GraphicsContext.Create(wx.PaintDC(self))

        path = gc.CreatePath()

        path.AddArc(450, 100, 30, math.radians(180), math.radians(0))
        pen = wx.Pen('#ffffff', 1)
        gc.SetBrush(wx.Brush('#CC7F32', wx.SOLID))
        gc.SetPen(pen)

        gc.DrawPath(path)

--
Regards,
Phil

[Andrea Gavana]

Hi,

Maybe you could take some inspiration from wx.lib.agw.speedometer:

https://wxpython.org/Phoenix/docs/html/wx.lib.agw.speedmeter.SpeedMeter.html

?

Andrea.

--
Regards,
Phil

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[Phil]

On 13/5/21 4:30 pm, Andrea Gavana wrote:
>
> Maybe you could take some inspiration from wx.lib.agw.speedometer:

Thank you Andrea,

Speedometer is rather complex plus the demo will not run because of an
invalid encoding error. I posted a question about this quite some time
ago but didn't receive a reply.

I now have my meter working and now have to sort out how to incorporate
it into it's own class. I have no idea how to do this, at the moment.

--

Regards,
Phil

[Chris Barker]

On Thu, May 13, 2021 at 2:55 PM Phil <phil...@gmail.com> wrote:

Speedometer is rather complex plus the demo will not run because of an
invalid encoding error.

an issue on gitHub might be good for that. -- but looking at the code may be helpful nonetheless.

 

I now have my meter working and now have to sort out how to incorporate
it into it's own class. I have no idea how to do this, at the moment.

look at the wiki and various demos, but in short:

create a subclass of wxPanel

Create a method to draw the dial.

Call that method from The OnPaint handler to a method that draws your dial.

When the data changes, call Refesh() on your panel -- that will trigger a Paint event, which will re-draw the dial.

You may want to have the dial itself be pre-saved to a bitmap, and then you can just re-draw the needle on top of it when things change.

These are a bit old, but may help:

https://github.com/PythonCHB/wxPythonDemos

-CHB

--

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[Phil]

On 4/7/21 2:45 am, 'Chris Barker' via wxPython-users wrote:
>
> I now have my meter working and now have to sort out how to
> incorporate
> it into it's own class. I have no idea how to do this, at the moment.
>
>

> create a subclass of wxPanel
>
> Create a method to draw the dial.
>
> Call that method from The OnPaint handler to a method that draws your
> dial.
>
> When the data changes, call Refesh() on your panel -- that will
> trigger a Paint event, which will re-draw the dial.
>
> You may want to have the dial itself be pre-saved to a bitmap, and
> then you can just re-draw the needle on top of it when things change.
>

Thank you Chris,

Perhaps I should have delayed my question until I'd had a good night's
sleep. I completed this project over a few days. Creating the dial in a
drawing programme was a far neater idea and saved a lot of coding.

--

Regards,
Phil