Bug: Listbox widget does not support monochrome displays

[erichiggins]

My setup:

• Pi Pico (RP2040)
• Monochrome OLED (SSD1309)
• Micropython 1.22.0

Issue details:

Note: The lack of monochrome support may affect other widgets as well, though I have only run into it with Listbox so far.

The Listbox widget only supports an alternate bgcolor to indicate which item is selected. There are two issues with this:

1. It doesn't work on monochrome displays
2. If a Listbox only has two options, it's not always clear which item is actually selected

Alternative suggestions

There are a few other ways to approach this problem and resolve the issue for monochrome displays:

1. Invert colors for selected elements
   • simple swap of fgcolor and bgcolor
   • could define a special "color" named INVERT within colors.py to trigger this within the widget by defining select_color=INVERT
2. Draw border around selected item
   • Visually, I don't prefer this option though it could be easier to implement
3. Define a character (e.g. > or -) to prepend to the selected item in the list
   • Requires the code to offset the text for the list to make room
   • Example:

     Red
     > Orange
     Yellow
     Green

[peterhinch]

I think this is an issue with many of the more complex controls. The gui makes extensive use of color. Greyscale monochrome displays work fairly well, but 1-bit monochrome displays don't. Perhaps I should point this out in the docs. 1-bit displays are OK for the simpler controls, but supporting the more complex controls would require substantial redesign.

I can't envisage undertaking this: I don't believe there is significant demand. Feel free to create your own fork!