Source code for BiblioPixelAnimations.strip.ColorChase

from bibliopixel.animation.strip import Strip


class ColorChase(Strip):
    """Chase one pixel down the strip."""
    COLOR_DEFAULTS = ('color', [255, 0, 0]),

    def __init__(self, layout, width=1, start=0, end=-1, **kwds):
        super().__init__(layout, start, end, **kwds)
        self._width = width

    def pre_run(self):
        self._step = 0

    def step(self, amt=1):
        self.layout.all_off()  # because I am lazy

        for i in range(self._width):
            self.layout.set(self._start + self._step + i, self.palette(0))

        self._step += amt
        overflow = (self._start + self._step) - self._end
        if overflow >= 0:
            self._step = overflow