from openexp.keyboard import keyboard

# Inter-stimulus interval
ITI = 50

# The number of cycles
n_cycles = 10

# Set-up a keyboard object with a timeout equal to the interval
# between the two stimuli
my_keyboard = keyboard(exp, timeout=ITI)

# Copy the canvas from two sketchpads. You will show these sketchpads
# here using inline_script, so in the experiment you probably want to
# 'hide' them by setting the run-if statement to 'never'. Of course, you
# can also canvases using inline script, instead of copying them from a
# sketchpad.
canvas_1 = self.copy_sketchpad('sketchpad_1')
canvas_2 = self.copy_sketchpad('sketchpad_2')

# Start the response interval
start_timestamp = self.time()

# We are going to keep a list of responses
resp_list = []

# Go into a loop where the two canvases are shown in alternation
for i in range(n_cycles):

    # Show the first canvas
    t1 = canvas_1.show()

    # Use the get_key() function to sleep and monitor for keypresses
    # at the same time.
    resp, t2 = my_keyboard.get_key()
    if resp != None:
        # If a key was pressed, add it to the list of responses.
        resp_list.append( (resp, t2) )
        # And also sleep for the remaining time of the ITI
        self.sleep(ITI - t2 + t1)

    # Same principle for the second canvas
    t1 = canvas_2.show()
    resp, t2 = my_keyboard.get_key()
    if resp != None:
        resp_list.append( (resp, t2) )
        self.sleep(ITI - t2 + t1)

# If the response_list is empty, no response was given
if len(resp_list) == 0:
    response = 'timeout'
    response_time = 0

# Otherwise get the first response from the list
else:
    resp, resp_timestamp = resp_list[0]
    response = resp
    response_time = start_timestamp - resp_timestamp

# Set the response variables!
exp.set('response', resp)
exp.set('response_time', response_time)

# To maintain feedback variables, see
# <http://osdoc.cogsci.nl/usage/giving-feedback-to-participants/#inline-script>