使用 Tkinter 逐个字母打印

Question

有没有办法在 Python 3.4.1 中使用 Tkinter 逐字打印（在帧更新之间重绘）？

这在普通的空闲窗口中使用这段代码是可行的：

import time
string = "hello world"
for char in string:
    print(char, end='')
    time.sleep(.25)

但我不能在 GUI Tkinter 窗口中执行此操作。在我看来，我可以在 tkinter 窗口上显示一个标签，从一个字符串中添加一个字母，然后等待一段时间再添加另一个字母（大约 0.25 秒），与上面的代码相同。 有什么解决办法吗？

例如：

要显示的字符串 = 'abc'

第一帧：'a'

第二帧：'ab'

第三帧：'abc'

提前致谢！

Answer 1

你没有具体说明，所以我猜你会喜欢这样的：

import time
import tkinter as tk


def printString(string):
    for char in string:
        Label.configure(text=Label.cget('text') + char)
        Label.update()
        time.sleep(.25)

root = tk.Tk()
text = "Hello world!"
Label = tk.Label(root)
Label.pack()
printString(text)
root.mainloop()

---

更新：

原理相同，但对于 canvas：

import time
import tkinter as tk


def printString(item, string):
    if item:
        for char in string:
            idx = c.index(item, tk.END)
            c.insert(item, idx, char)
            c.update()
            time.sleep(.25)


root = tk.Tk()
text = "Hello world!"
c = tk.Canvas(root)
c_txt = c.create_text(50,50)
c.pack()
c.update()
printString(c_txt, text)

root.mainloop()

Answer 2

您可以使用after 定期调用方法来更新GUI。 time.sleep 不像阻止 GUI 运行的主线程一样容易使用。

---

您可以定期替换label的单个字符文本字符串中的下一个字母：

 try:
    import tkinter as tk
except:
    import Tkinter as tk


def update_label_letter():
    global label
    label['text'] = label.string[label.current_char_index]
    label.current_char_index += 1
    label.current_char_index %= len(label.string)
    label.after(250, update_label_letter)


if __name__ == '__main__':
    root = tk.Tk()
    label = tk.Label(root)
    label.string = "Hello World!"
    label.current_char_index = 0
    root.after(250, update_label_letter)
    label.pack()
    root.mainloop()

---

一种方法是定期追加单个label的字母。

垂直：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def update_label_letters():
    global label
    _no_of_space_replacements = label['text'].count('\n')
    _last_char_index = len(label['text']) - _no_of_space_replacements
    if _last_char_index < len(label.string):
        label['text'] += label.string[_last_char_index].replace(" ", " \n")
    else:
        label['text'] = ""
    label.after(250, update_label_letters)


if __name__ == '__main__':
    root = tk.Tk()
    label = tk.Label(root, wraplength=1)
    label.string = "Hello World!"
    root.after(250, update_label_letters)
    label.pack()
    root.mainloop()

水平：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def update_label_letters():
    global label
    _last_char_index = len(label['text'])
    if _last_char_index < len(label.string):
        label['text'] += label.string[_last_char_index]
    else:
        label['text'] = ""
    label.after(250, update_label_letters)


if __name__ == '__main__':
    root = tk.Tk()
    label = tk.Label(root)
    label.string = "Hello World!"
    root.after(250, update_label_letters)
    label.pack()
    root.mainloop()

---

另一种方法是定期写字母清空但显示letter_labels。

垂直：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def update_label_letters():
    global current_char_index, my_string, letter_labels
    if current_char_index < len(my_string):
        _current_char = my_string[current_char_index]
        letter_labels[current_char_index]['text'] = _current_char
        letter_labels[current_char_index].after(250, update_label_letters)
        current_char_index += 1


if __name__ == '__main__':
    root = tk.Tk()

    my_string = "Hello World!"
    letter_labels = list()
    for index, value in enumerate(my_string):
        letter_labels.append(tk.Label(root))
        letter_labels[index].pack()
    current_char_index = 0
    root.after(250, update_label_letters)
    root.mainloop()

水平：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def update_label_letters():
    global current_char_index, my_string, letter_labels
    if current_char_index < len(my_string):
        _current_char = my_string[current_char_index]
        letter_labels[current_char_index]['text'] = _current_char
        letter_labels[current_char_index].after(250, update_label_letters)
        current_char_index += 1


if __name__ == '__main__':
    root = tk.Tk()

    my_string = "Hello World!"
    letter_labels = list()
    for index, value in enumerate(my_string):
        letter_labels.append(tk.Label(root))
        letter_labels[index].pack(side='left')
    current_char_index = 0
    root.after(250, update_label_letters)
    root.mainloop()

---

另一种方法是定期显示letter_labels。

垂直：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def show_label():
    global current_char_index, my_string, letter_labels
    if current_char_index < len(my_string):
        letter_labels[current_char_index].pack()
        letter_labels[current_char_index].after(250, show_label)
        current_char_index += 1


if __name__ == '__main__':
    root = tk.Tk()

    my_string = "Hello World!"
    letter_labels = list()
    for _char in my_string:
        letter_labels.append(tk.Label(root, text=_char))
    current_char_index = 0
    root.after(250, show_label)
    root.mainloop()

水平：

try:
    import tkinter as tk
except:
    import Tkinter as tk


def show_label():
    global current_char_index, my_string, letter_labels
    if current_char_index < len(my_string):
        letter_labels[current_char_index].pack(side='left')
        letter_labels[current_char_index].after(250, show_label)
        current_char_index += 1


if __name__ == '__main__':
    root = tk.Tk()

    my_string = "Hello World!"
    letter_labels = list()
    for _char in my_string:
        letter_labels.append(tk.Label(root, text=_char))
    current_char_index = 0
    root.after(250, show_label)
    root.mainloop()