如何增加turtle.tracer() 的延迟？ [PYTHON]

Question

我正在 Pyzo 中做一个练习项目，但在使用 turtle.tracer() 时遇到了一些问题。

当 n =/= 0 或 1 时，我遇到了屏幕上的对象开始闪烁的问题。

import turtle
sketcher = turtle.Turtle()
canvas = turtle.Screen()

sketcher.speed(0)
sketcher.hideturtle()

def drawPinwheelAnimation(length):
    sketcher.setheading(90)
    backwardLength = length
    lengthChange = 1
    while(True):
        canvas.tracer(36)
        drawPinwheel(0, 0, length, backwardLength)
        drawPinwheel(3*length, 0, length, backwardLength)
        drawPinwheel(0, 3*length, length, backwardLength)
        drawPinwheel(-3*length, 0, length, backwardLength)
        drawPinwheel(0, -3*length, length, backwardLength)
        canvas.update()
        backwardLength += lengthChange
        if(backwardLength == (1.5*length) or backwardLength == (0.5*length)):
            lengthChange *= -1
        sketcher.clear()

def drawSwingingPinwheel(xPos, yPos, initialLength):
    while(True):
        drawPinwheel(xPos, yPos, forwardLength, backwardLength)
        backwardLength += lengthChange
        if(backwardLength == (1.5*initialLength) or backwardLength == (0.5*initialLength)):
            lengthChange *= -1
        sketcher.clear()


def drawPinwheel(xPos, yPos, fdLength, bkLength):
    sketcher.penup()
    sketcher.setpos(xPos, yPos)
    sketcher.pendown()
    for side in range(12):
        sketcher.fd(fdLength)
        sketcher.bk(bkLength)
        sketcher.rt(30)

drawPinwheelAnimation(50)

turtle.mainloop()

n = 1时，没有闪烁，但也意味着动画无论如何都是以基本速度进行的，所以没有效果。当 n = 0 时，没有闪烁。但是，这对我的目的来说太快了。我尝试更改“延迟”值，但无济于事：

        canvas.tracer(0, 1000) #Changing the second value to 1000 has no notable difference.
        drawPinwheel(0, 0, length, backwardLength)
        drawPinwheel(3*length, 0, length, backwardLength)
        drawPinwheel(0, 3*length, length, backwardLength)
        drawPinwheel(-3*length, 0, length, backwardLength)
        drawPinwheel(0, -3*length, length, backwardLength)
        canvas.update()

在这一点上我很困惑。我不确定，我可能缺少一个非常明显的解决方案。

谢谢！

Answer 1

我终于找到了答案！

在 Screen.update() 之后可以使用一个函数，称为 time.sleep()。如果你在 time.sleep() 中输入一个值，它会在再次刷新之前暂停几秒。

例如，我通过这样做修复了自己的代码：

import turtle
import time
sketcher = turtle.Turtle()
canvas = turtle.Screen()

sketcher.speed(0)
sketcher.hideturtle()

def drawPinwheelAnimation(length):
    sketcher.setheading(90)
    backwardLength = length
    lengthChange = 1
    while(True):
        canvas.tracer(0)
        drawPinwheel(0, 0, length, backwardLength)
        drawPinwheel(3*length, 0, length, backwardLength)
        drawPinwheel(0, 3*length, length, backwardLength)
        drawPinwheel(-3*length, 0, length, backwardLength)
        drawPinwheel(0, -3*length, length, backwardLength)
        canvas.update()
        time.sleep(.01) # <-------- Here's the time.sleep() function!
        backwardLength += lengthChange
        if(backwardLength == (1.5*length) or backwardLength == (0.5*length)):
            lengthChange *= -1
        sketcher.clear()

def drawSwingingPinwheel(xPos, yPos, initialLength):
    while(True):
        drawPinwheel(xPos, yPos, forwardLength, backwardLength)
        backwardLength += lengthChange
        if(backwardLength == (1.5*initialLength) or backwardLength == (0.5*initialLength)):
            lengthChange *= -1
        sketcher.clear()


def drawPinwheel(xPos, yPos, fdLength, bkLength):
    sketcher.penup()
    sketcher.setpos(xPos, yPos)
    sketcher.pendown()
    for side in range(12):
        sketcher.fd(fdLength)
        sketcher.bk(bkLength)
        sketcher.rt(30)

drawPinwheelAnimation(50)

turtle.mainloop()

希望这对任何人都有帮助！

Answer 2

你不需要也不想time.sleep()。首先，您需要根据tracer() 和update() 适当地安排您的程序：

from turtle import Screen, Turtle

def drawPinwheelAnimation(length, lengthChange=1, backwardLength=None):
    if backwardLength is None:
        backwardLength = length

    turtle.clear()

    drawPinwheel(0, 0, length, backwardLength)
    drawPinwheel(3*length, 0, length, backwardLength)
    drawPinwheel(0, 3*length, length, backwardLength)
    drawPinwheel(-3*length, 0, length, backwardLength)
    drawPinwheel(0, -3*length, length, backwardLength)

    screen.update()

    backwardLength += lengthChange

    if backwardLength == (1.5*length) or backwardLength == 0.5*length:
        lengthChange *= -1

    screen.ontimer(lambda: drawPinwheelAnimation(length, lengthChange, backwardLength), 100)

def drawPinwheel(xPos, yPos, fdLength, bkLength):
    turtle.penup()
    turtle.setpos(xPos, yPos)
    turtle.pendown()

    for _ in range(12):
        turtle.forward(fdLength)
        turtle.backward(bkLength)
        turtle.right(30)

screen = Screen()
screen.tracer(False)

turtle = Turtle()
turtle.hideturtle()
turtle.setheading(90)

drawPinwheelAnimation(50)

screen.mainloop()

其次，我用计时器事件替换了您的while True:，它在乌龟这样的事件驱动环境中没有位置。注意ontimer() 的第二个参数，它是再次调用此方法之前的时间延迟。