def main():
colors = ["red", "green", "blue", "yellow", "magenta", "cyan"]
hist = history(device)
while True:
# Phase 1: Redraw on a fresh canvas each loop
for idx, color in enumerate(colors):
with canvas(hist) as draw:
render_box(draw, idx, color)
hist.savepoint()
time.sleep(1)
while len(hist) > 0:
# Drop every other save point
hist.restore(drop=1)
time.sleep(1)
# Phase 2: Notice the difference with the above?
# ... redraw on the *same* canvas
c = canvas(hist)
for idx, color in enumerate(colors):
with c as draw:
render_box(draw, idx, color)
hist.savepoint()
time.sleep(1)
while len(hist) > 0:
hist.restore()
time.sleep(1)
def test_drop_and_restore():
device = dummy()
hist = history(device)
copies = []
for i in range(10):
with canvas(hist) as draw:
draw.text((10, 10), text="Hello {0}".format(i), fill="white")
hist.savepoint()
copies.append(device.image)
hist.restore()
assert device.image == copies[9]
hist.restore(drop=2)
assert device.image == copies[6]
hist.restore(drop=4)
assert device.image == copies[1]
assert len(hist) == 1
def test_save_and_restore_reverts_image():
device = dummy()
hist = history(device)
with canvas(hist) as draw:
baseline_data.primitives(hist, draw)
img1 = device.image
hist.savepoint()
assert len(hist) == 1
with canvas(hist) as draw:
draw.text((10, 10), text="Hello", fill="white")
img2 = device.image
assert img1 != img2
hist.restore()
img3 = device.image
assert img1 == img3
assert len(hist) == 0
def test_restore_throws_error_when_empty():
device = dummy()
hist = history(device)
assert len(hist) == 0
with pytest.raises(IndexError):
hist.restore()
