Generate simple image on a standalone Raspberrry Pi

[Roy Hann]

Eli the Bearded wrote:

> In comp.lang.python, Roy Hann  <specially at processed.almost.meat> wrote:
>> I am designing a mobile application to run on a Raspberry Pi 3 model B.
>> It will not have any Internet access. I need to generate a static image
>> consisting of a simple arc representing (say) a speedometer or a
>> pressure gauge. The image will need to be regenerated every 5 seconds.
>> The image must be displayed in a web browser (served by gunicorn
>> running on the Pi). I prefer it to be a PNG but that is only a
>> preference.
>
> The browser can probably display SVG. So generating that may be easier.
> Is the browser running on the same system? You say no "Internet access",
> but that's not the same as "no network access". 

You are correct to this point; the Pi is serving HTML to the
experimental browser on a Kindle 4 over wifi.

> A browser running on a
> different local system might have more CPU oomph to handle the "SVG to
> bitmap for display" step.

Sadly the Kindle, impressive as it is, ain't no workhorse. 

That said, I've only assumed it would be more efficient to hand it PNGs
to render. I should actually test it rendering SVGs. I set out down the
PNG road on the assumption PNGs would be easy to generate.

Thanks for steering me back to SVG.

Roy