Change widget background color

[woshibala]

Hi there, I am working on adding a new module and widget to show the Allen Dev. I was wondering how can I use your spectrum module and let it plot in a fixed interval.

Also, The plot background is black, and I was trying to change it into white. But I can find where I can make this change, or there is no background for plot and I need to add a background to it?

Thanks,

[lneuhaus]

Hi, welcome to the developers! If you are thinking about sharing your modifications with us or others in the future, I highly recommend you to fork the repository before modifying it. This will make discussing your code easier in the future.

Also, the current documentation is definitely not at a state that would allow you to reasonable develop code based on that. We will be fixing that soon (hopefully), but if you are in a hurry, dont hesitate to ask a lot of questions here or you might have to read a lot of unuseful code for your purpose.

Now your first question:

If you simply want the spectrum analyzer to plot a new curve every so and so seconds, the easiest way is to periodically call (sa is the specan module here, set sa.trace_averages=1 before if you do not want to average several traces):

sa.single()  # blocking until spectrum acquisition is finished

or

sa.single_async()  # running in the background, returns a 'future'

We have a module called Loop (see the file loop.py) for periodic calls which you might want to use for this, otherwise QTimers are fine, too.

If you could be a little more specific, maybe with some of your code (if there is already any), I can probably extend this answer on the topic that needs more explanation.

Then, your second question about the background:

We use pyqtgraph for all plots (with default configuration), and the relevant commands seem to be documented here: http://www.pyqtgraph.org/documentation/style.html#default-background-and-foreground-colors

Copy-paste:

## Switch to using white background and black foreground
pg.setConfigOption('background', 'w')
pg.setConfigOption('foreground', 'k')

(Note that this must be set before creating any widgets)

What exact code snippet do you use to plot? With that information, I could suggest a nice place to insert this into the code if you want me to..

[woshibala]

Hi,

Thanks for your reply. I tried to change the background according to your answer, and it works! I am going to look into the loop.py and QTimers.

I am also working on plot data on polar coordinates, and it rather different from any pyrpl widget. Do you have any suggestion how can I implement polar coordinates based on your work?

Thanks again! Have a good day.

[lneuhaus]

Cool. loop.py is essentially just a wrapper around QTimers, so reading the code might be a good example to see how QTimers can be used, and then to decide whether to use the wrapper or a custom implementation.

For polar coordinates I have not much to say. A quick search revealed this proposition which seems to work with pyqtgraph: https://groups.google.com/forum/#!topic/pyqtgraph/9Vv1kJdxE6U

Otherwise, if you do not plot too frequently, the somewhat slower plots produced with matplotlib should do the job as well.