python turtle奇怪的光标跳

Question

我正在尝试使用鼠标绘制龟,我在下面的演示代码工作,但有时鼠标移动时光标跳转:

#!/usr/bin/env python
import turtle
import sys

width = 600
height = 300
def gothere(event):
    turtle.penup()
    x = event.x
    y = event.y
    print "gothere (%d,%d)"%(x,y)
    turtle.goto(x,y)
    turtle.pendown()

def movearound(event):
    x = event.x
    y = event.y
    print "movearound (%d,%d)"%(x,y)
    turtle.goto(x,y)

def release(event):
    print "release"
    turtle.penup()

def circle(x,y,r):
    turtle.pendown() 
    turtle.goto(x,y)
    turtle.circle(r)
    turtle.penup()
    return

def reset(event):
    print "reset"
    turtle.clear()

#------------------------------------------------#
sys.setrecursionlimit(90000)
turtle.screensize(canvwidth=width, canvheight=height, bg=None)
turtle.reset()
turtle.speed(0)
turtle.setup(width, height)

canvas = turtle.getcanvas()

canvas.bind("<Button-1>", gothere)
canvas.bind("<B1-Motion>", movearound)
canvas.bind("<ButtonRelease-1>", release)
canvas.bind("<Escape>",reset)

screen = turtle.Screen()
screen.setworldcoordinates(0,height,width,0)
screen.listen()

turtle.mainloop()
#------------------------------------------------#

看下面的gif实际行为:

不确定是否有任何API调用错误!

Answer 1

我看到你的代码有几个问题:

• 您正在将面向对象的接口与该模块的功能接口混合在一起.我推荐一个或另一个,但不是两个.请参阅我的import更改以强制仅限OOP.

• 你正在使用低级tkinter鼠标和关键事件而不是龟自己的事件.我建议你尝试在乌龟级别工作(虽然这会引入一个与你的实现相比的故障,见下文.)

• 您通过不关闭事件处理程序中的事件来引入意外的递归.禁用那些占用大量时间的处理程序中的事件将清理您的图形.

这是我在上面的代码中对代码的修改.一个小问题是,与原始版本不同,"移动乌龟在这里"和"开始拖动"将需要两次点击,一次单击屏幕将乌龟移动到当前位置,一次单击鼠标开始拖动.这是由于turtle为tkinter事件提供的接口不同.(Python 3在这方面要好一些,但不适用于这种情况.)

为了简化这一点,我使用了一个更大的乌龟光标.我还添加了标题逻辑:

from turtle import Turtle, Screen, mainloop

WIDTH = 600
HEIGHT = 300

def gothere(x, y):
    screen.onscreenclick(gothere)  # disable events inside handler

    turtle.penup()
    print("gothere (%d,%d)" % (x, y))
    turtle.goto(x, y)
    turtle.pendown()

    screen.onscreenclick(gothere)

def movearound(x, y):
    turtle.ondrag(None)  # disable events inside handler

    turtle.setheading(turtle.towards(x, y))
    print("movearound (%d,%d)" % (x, y))
    turtle.goto(x, y)

    turtle.ondrag(movearound)

def release(x, y):
    print("release (%d,%d)" % (x, y))
    turtle.penup()

def reset():
    print("reset")
    turtle.clear()

screen = Screen()
screen.setup(WIDTH, HEIGHT)
# screen.setworldcoordinates(0, HEIGHT, WIDTH, 0)  # should work fine either way

turtle = Turtle('turtle')
turtle.speed('fastest')

turtle.ondrag(movearound)
turtle.onrelease(release)

screen.onscreenclick(gothere)
screen.onkey(reset, "Escape")

screen.listen()

mainloop()  # normally screen.mainloop() but not in Python 2

但是也看到了这个答案,我展示了如何让tkinter的onmove事件可用于龟.

..."移动到这里"然后"开始拖动"限制对用户来说非常不舒服？我们怎样才能改善这一点？

将上面的代码与我链接到的备用答案相结合,我们得到的解决方案类似于您开始的地方,但没有毛刺,而且更像是乌龟风格:

from turtle import Turtle, Screen, mainloop
from functools import partial

WIDTH = 600
HEIGHT = 300

VERBOSE = False

def onscreenmove(self, fun, btn=1, add=None):  # method missing from turtle.py

    if fun is None:
        self.cv.unbind('<Button%s-Motion>' % btn)
    else:
        def eventfun(event):
            fun(self.cv.canvasx(event.x) / self.xscale, -self.cv.canvasy(event.y) / self.yscale)

        self.cv.bind('<Button%s-Motion>' % btn, eventfun, add)

def onscreenrelease(self, fun, btn=1, add=None):  # method missing from turtle.py

    if fun is None:
        self.cv.unbind("<Button%s-ButtonRelease>" % btn)
    else:
        def eventfun(event):
            fun(self.cv.canvasx(event.x) / self.xscale, -self.cv.canvasy(event.y) / self.yscale)

        self.cv.bind("<Button%s-ButtonRelease>" % btn, eventfun, add)

def gothere(x, y):

    if VERBOSE:
        print("gothere (%d,%d)" % (x, y))

    turtle.penup()
    turtle.goto(x, y)
    turtle.pendown()

def movearound(x, y):

    screen.onscreenmove(None)  # disable events inside handler

    if VERBOSE:
        print("movearound (%d,%d)" % (x, y))


    turtle.setheading(turtle.towards(x, y))
    turtle.goto(x, y)

    screen.onscreenmove(movearound)  # reenable events

def release(x, y):

    if VERBOSE:
        print("release (%d,%d)" % (x, y))

    turtle.penup()

def reset():

    if VERBOSE:
        print("reset")

    turtle.clear()

screen = Screen()
screen.setup(WIDTH, HEIGHT)
screen.onscreenrelease = partial(onscreenrelease, screen)  # install missing methods
screen.onscreenmove = partial(onscreenmove, screen)

turtle = Turtle('turtle')
turtle.speed('fastest')

screen.onscreenclick(gothere)
screen.onscreenrelease(release)
screen.onscreenmove(movearound)

screen.onkey(reset, "Escape")
screen.listen()

mainloop()  # normally screen.mainloop() but not in Python 2