Adding ScrollingLabel

[FoamyGuy]

This adds a new ScrollingLabel that is a fixed-width label that can scroll the text leftward like a marquee.

An example has been provided to show the most basic usage.

This component is used in my PyPortal Winamp player project but I figured this piece is generic enough to re-used for other purposes.

[kmatch98]

• I verified that label_direction works as expected giving different rotation options.
• I verified that background_color works. On proportional fonts, the right side of the label gets resized as it scrolls, that's just a consequence of the backside bounding box changing sizes. That could be an area for future improvement.
• Redefining full_text works too.

One item for consideration:

The keyword argument full_text had to be used so that you wouldn't conflict with the existing superclass .text property. And I see you put a warning, but it seems a little harder to use that way.

Perhaps making the this a subclass Group (that contains your Label) would give you the flexibility to use an input parameter named text. This will make its external definition more similar to Label and then easier to convert between Label and ScrollingLabel.

[FoamyGuy]

Thanks for taking a look. I do like this idea better to use text instead of full_text and switch the parent class to allow for it. I'll make that change tonight and add a new commit with it.

[FoamyGuy]

After tinkering with it for a bit I'm interested to see if there is a way to do this without having to extend Group instead of Label. If we change the super class it means we would lose all of the "pass through" properties so for setting things like color or background_color get tricky.

Something like this would no longer work:

my_scrolling_label.color = 0x00ff00

we could add "boilerplate" properties that copy all of the Label ones and pass them through to the Label instance but I wonder if there is some way we can avoid needing all of the extra code to re-declare each property.

I have changed the argument name to text instead of full_text and removed the warning. All of this does work as-is. But it does kind of leave open the issue that user might get unexpected results if they are changing the text after the fact trying to do something like:

my_scrolling_label.text = "the new text long enough to scroll"

[kmatch98]

Thanks for the comments about using Label versus Group, and it makes sense. It's awkward to initialize with text input parameter and then full_text as a getter/setter but I understand the limit. I remember previously trying to overriding Group's superclass instance variables versus subclass variables and hit one of the limits of CircuitPython (I think it was with scaling).

Oh, and thanks for catching the example code update.

I think this is ok for now, so I'll merge it.