Icon instructions outdated and examples not updated

[djchadderton]

It seems that the code for drawing icons on the menu screen was changed to use a symbols font 5 months ago but the instructions on the Pimoroni web site still say this should be a list of points to create a vector shape and only the example apps that are included in the retail version have been updated in this repository. Adding these to the Presto will prevent it from displaying the menu at all as there is no error checking to enable it to either work with the old system or fail gracefully.

The apps in the examples file that fail in this way are agile_pricing_display.py, auto_backlight.py, backlight_slider.py and indoor-outdoor-temp.py.

I assume from reading the code that rather than simply adding an app to the root directory as before (and as the instructions still state), to add an app to the menu, it has to be added to the icons dictionary in main.py with the icon name given in the file as a key and the unicode value as value.

A list of icons included with their unicode values would be very useful. I've tried some values I've found elsewhere that seem to relate to the included font, but none of them have worked, but at least they just leave the icon blank rather than crashing.

[djchadderton]

I've managed to make some changes to the main.py file that will allow the current method of referencing an entry in the icons list or using a list of values to provide backwards compatibility with older app files with vector coordinates.

Firstly in the __init__ method of the Application class, replace the first if statement in the for loop with:

if line.startswith("# ICON "): # Find a header line with an icon value
    icon = line[7:].strip()
    if icon.startswith("["): # a list of values for a vector shape
        self.icon = Polygon()
        try:
            for path in eval(icon):
                self.icon.path(*path)
        except:  # noqa: E722 - eval could barf up all kinds of nonsense
            pass
    else: # a string referencing a key in the icons dictionary
        self.icon = icons[icon]

Some of this has been resurrected from previous code.

Then in the draw method, replace vector.text(self.icon, 0, 0) with:

if type(self.icon).__name__ == "polygon":
    vector.draw(self.icon)
else:
    vector.text(self.icon, 0, 0)

This seems to work fine, though a little clunky in testing the type before drawing.