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@jmxpearson
Created August 18, 2016 19:58
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from psychopy import core, visual
from psychopy.visual.circle import Circle
class Flicker(Circle):
"""
Creates a flickering circle in the upper right corner of the screen.
This is to be used as a timing marker by a photodiode.
The presence or absence of the circle marks out an 8-bit binary pattern,
flanked at the beginning and end by a 1 (e.g., 5 is 1000001011).
"""
def __init__(self, win, radius=0.04, pos=(0.84, 0.44), **kwargs):
self.win = win
self.bitpattern = None
self.counter = None
self.timer = core.MonotonicClock()
kwargs['radius'] = radius
kwargs['pos'] = pos
# we want to override these
kwargs['fillColorSpace'] = 'rgb255'
kwargs['lineColorSpace'] = 'rgb255'
kwargs['lineColor'] = None
kwargs['units'] = 'height'
kwargs['autoDraw'] = True
super(Flicker, self).__init__(win, **kwargs)
def flicker(self, code):
"""
Start the flicker. code is an integer between 0 and 255 (=2^8).
Calling this again before the sequence has finished will
restart the flicker.
"""
# convert to binary, zero pad to 8 bits, and add stop and start bits
self.bitpattern = '1{:08b}1'.format(code)
self.counter = 0
def flicker_block(self, code):
"""
Blocking version of flicker. The entire task will pause until the flicker is done. Returns the time of execution of the function.
This is not best practice, but can be used in code that does not
run a single event loop where flicker can be used.
"""
start_time = self.timer.getTime()
self.flicker(code)
while self.bitpattern:
self.win.flip()
end_time = self.timer.getTime()
return end_time - start_time
def draw(self):
"""
Draw the circle. Change its color based on the bitpattern and forward
to the draw method for the circle.
"""
if self.bitpattern:
# if we've reached the end of the pattern
if self.counter >= len(self.bitpattern):
self.bitpattern = None
self.fillColor = self.win.color
else:
if self.bitpattern[self.counter] == '1':
self.fillColor = (255, 255, 255)
else:
self.fillColor = (0, 0, 0)
# increment position in bit pattern
self.counter += 1
super(Flicker, self).draw()
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