python - 如何在 Tkinter Canvas 中为子字符串着色

Question

我正在编写一个程序，涉及在 create_text() 中显示一些文本Tkinter Canvas 上的框，在一个循环中。显示每个单词，然后由下一个替换。有点像闪存卡。

我需要为每个单词的一个字母着色，靠近单词的中间，这样当用户阅读单词时，他们的眼睛会聚焦在单词的中间。所以if len(i)=1, color i[0], if len(i)>= 2 and <= 5, color i[1] ， 等等。它需要使用 Canvas 完成，并使用

canvas.create_text(text = i[focus_index],fill = 'red') 

结果应该这样打印

exaMple

(但显然“m”会变成红色，而不是大写)

Answer 1

我假设你想要类似 this 的东西？

这是我目前能得到的最接近的。它创建了三个文本框并使用 anchor 属性将它们保持在正确的位置。但是，它对于非常宽或窄的字母效果不是很好。它并不完美，但可能是一个开始。

import Tkinter as tk

root = tk.Tk()

c = tk.Canvas(root)
c.pack(expand=1, fill=tk.BOTH)

words = '''I am writing a program that involves displaying some text in a create_text() box on a Tkinter canvas, within a loop. Each word is displayed, then replaced by the next. Sort of like flash cards. I need to color one letter of each word, close to the middle of the word, so that when the user is reading the words their eyes focus on the middle of the word. So if len(i)=1, color i[0], if len(i)>= 2 and <= 5, color i[1], and so on. It needs to be done using the Canvas, and using canvas.create_text(text = i[focus_index],fill = 'red') The result should print like this exaMple (but obviously "m" would be colored red, not be uppercase)'''
words = words.split()

def new_word(i):
    if i == len(words):
        i = 0

    word = words[i]
    middle = (len(word)+1)//2
    c.itemconfigure(t1, text=word[:middle-1]+' ')
    c.itemconfigure(t2, text=word[middle-1:middle])
    c.itemconfigure(t3, text=word[middle:])

    root.after(100, lambda: new_word(i+1))


t1 = c.create_text(200,100,text='', anchor='e', font=("Courier", 25))
t2 = c.create_text(200,100,text='', anchor='e', font=("Courier", 25), fill='red')
t3 = c.create_text(200,100,text='', anchor='w', font=("Courier", 25))
new_word(0)

root.geometry('400x200+200+200')
root.mainloop()

---

好的，使用来自 Bryan Oakley's comment 的链接，我进一步改进了代码，使其适用于任何字体，而不仅仅是等宽字体。该代码将彩色字母的中心保持在同一位置，并将单词的前后放置在其周围的正确距离处。

import Tkinter as tk
import tkFont

root = tk.Tk()
c = tk.Canvas(root)
c.pack(expand=1, fill=tk.BOTH)

fn = "Helvetica"
fs = 24
font = tkFont.Font(family=fn, size=fs)

words = '''I am writing a program that involves displaying some text in a create_text() box on a Tkinter canvas, within a loop. Each word is displayed, then replaced by the next. Sort of like flash cards. I need to color one letter of each word, close to the middle of the word, so that when the user is reading the words their eyes focus on the middle of the word. So if len(i)=1, color i[0], if len(i)>= 2 and <= 5, color i[1], and so on. It needs to be done using the Canvas, and using canvas.create_text(text = i[focus_index],fill = 'red') The result should print like this exaMple (but obviously "m" would be colored red, not be uppercase)'''
words = words.split()

def new_word(i):
    if i == len(words):
        i = 0

    word = words[i]
    middle = (len(word)+1)//2

    front = word[:middle-1]
    letter = word[middle-1:middle]
    back = word[middle:]

    c.itemconfigure(t1, text=front)
    c.itemconfigure(t2, text=letter)
    c.itemconfigure(t3, text=back)
    c.coords(t1, 200-font.measure(letter)/2, 100)
    c.coords(t3, 200+font.measure(letter)/2, 100)

    root.after(100, lambda: new_word(i+1))


t1 = c.create_text(200,100,text='', anchor='e', font=font)
t2 = c.create_text(200,100,text='', anchor='c', font=font, fill='red')
t3 = c.create_text(200,100,text='', anchor='w', font=font)
new_word(0)

root.geometry('400x200+200+200')
root.mainloop()