Sawtooth tkinter主循环帧持续时间？

Question

尝试使用tkinter动画一系列PIL图像。我的帧持续时间（ms）的图形如下所示：

任何人都知道是什么原因导致这种刺尖的锯齿模式？

这是一个重现的脚本：

from PIL import Image, ImageTk
import Tkinter

import time
import sys

def generate_frames(n):
    """
    keep n under 101 * 101
    """
    out = []
    last_pil = None
    for i in range(n):
        if last_pil:
            pil_image = last_pil.copy()
        else:
            pil_image = Image.new('L', (101, 101), 255)   
        x = i / 101
        y = i % 101
        pil_image.load()[x, y] = 0
        out.append(ImageTk.PhotoImage(pil_image))
        last_pil = pil_image

    return out

def draw():
    FRAME_COUNT =5000

    master = Tkinter.Tk()

    w = Tkinter.Canvas(master, width=302, height=302)
    w.create_rectangle(49, 49, 252, 252)
    w.pack()

    frames = generate_frames(FRAME_COUNT)

    def draw_frame(f, canvas_image):
        print repr(time.time())
        frame = frames[f]
        if canvas_image is None:
            canvas_image = w.create_image((151, 151), image=frame, anchor='center')
        else:
            w.itemconfigure(canvas_image, image=frame)

        w.current_frame = frame  # save a reference
        next_frame = f + 1
        if next_frame < FRAME_COUNT:
            master.after(1, draw_frame, next_frame, canvas_image)
        else:
            sys.exit(0)

    master.after(10, draw_frame, 0, None)
    master.mainloop()


draw()

通过

查看图表，管道输出

import sys

last = None
for line in sys.stdin:
    value = float(line.strip()) * 1000
    if last is None:
        pass
    else:
        print (value - last)
    last = value

然后通过

from matplotlib import pyplot
import sys

X = []
Y = []

for index, line in enumerate(sys.stdin):
    line = line.strip()
    X.append(index)
    Y.append(float(line))

pyplot.plot(X, Y, '-')
pyplot.show()

使其成为多线程无济于事：

class AnimationThread(threading.Thread):

    FRAME_COUNT = 5000

    def __init__(self, canvas):
        threading.Thread.__init__(self)
        self.canvas = canvas
        self.frames = generate_frames(self.FRAME_COUNT)

    def run(self):
        w = self.canvas
        frames = self.frames
        canvas_image = None
        for i in range(self.FRAME_COUNT):
            print repr(time.time())
            frame = frames[i]
            if canvas_image is None:
                canvas_image = w.create_image((151, 151), image=frame, anchor='center')
            else:
                w.itemconfigure(canvas_image, image=frame)
            w.current_frame = frame
            time.sleep(1 * .001)

def draw_threaded():
    FRAME_COUNT = 5000
    master = Tkinter.Tk()

    w = Tkinter.Canvas(master, width=302, height=302)
    w.create_rectangle(49, 49, 252, 252)
    w.pack()

    animation_thread = AnimationThread(w)
    animation_thread.start()

    master.mainloop()

    animation_thread.join()

draw_threaded()

Answer 1

当竞争60和50 Hz样本混合时，这种干扰模式非常类似：

(Original Wolfram|Alpha plot)

这可能是由于两个事物处于不同（但接近）的刷新率造成的。当你试图拍摄电视屏幕并且它看起来像黑色条形图一直沿着图像移动时，或者当汽车车轮在汽车广告中围绕它们的车轴向后旋转时，就会发生同样类型的事情。它本质上是Moiré Effect的扩展。

我不知道它是否是由视频驱动程序和/或硬件引起的，但几乎可以肯定是由于干扰周期性模式造成的。看起来很像应该是GC循环干扰你的for循环（因此当内存被释放并且可以分配时，锯齿状波的突然下降）