How to change the color of certain words in the tkinter text widget?

Question

I have a program that I want to be like the Python shell and change color of certain words when they are typed. Any help?

Answer 1

The main idea is to apply tags to the parts of text you want to customise. You can create your tags using the method tag_configure, with a specific style, and then you just need to apply this tag to the part of text you want to change using the method tag_add. You can also remove the tags using the method tag_remove.

The following is an example that uses tag_configure, tag_add and tag_remove methods.

#!/usr/bin/env python3

import tkinter as tk
from tkinter.font import Font

class Pad(tk.Frame):

    def __init__(self, parent, *args, **kwargs):
        tk.Frame.__init__(self, parent, *args, **kwargs)

        self.toolbar = tk.Frame(self, bg="#eee")
        self.toolbar.pack(side="top", fill="x")

        self.bold_btn = tk.Button(self.toolbar, text="Bold", command=self.make_bold)
        self.bold_btn.pack(side="left")

        self.clear_btn = tk.Button(self.toolbar, text="Clear", command=self.clear)
        self.clear_btn.pack(side="left")

        # Creates a bold font
        self.bold_font = Font(family="Helvetica", size=14, weight="bold")

        self.text = tk.Text(self)
        self.text.insert("end", "Select part of text and then click 'Bold'...")
        self.text.focus()
        self.text.pack(fill="both", expand=True)

        # configuring a tag called BOLD
        self.text.tag_configure("BOLD", font=self.bold_font)

    def make_bold(self):
        # tk.TclError exception is raised if not text is selected
        try:
            self.text.tag_add("BOLD", "sel.first", "sel.last")        
        except tk.TclError:
            pass

    def clear(self):
        self.text.tag_remove("BOLD",  "1.0", 'end')


def demo():
    root = tk.Tk()
    Pad(root).pack(expand=1, fill="both")
    root.mainloop()


if __name__ == "__main__":
    demo()

If you don't know what sel.first and sel.last are, check out this post or this reference.

Answer 2

I have made a chat client. I highlighted certain parts of the conversation using a custom quite easy to use Text widget that allows you to apply tags using regular expressions. It was based on the following post: How to highlight text in a tkinter Text widget.

Here you have an example of use:

# "text" is a Tkinter Text

# configuring a tag with a certain style (font color)
text.tag_configure("red", foreground="red")

# apply the tag "red" 
text.highlight_pattern("word", "red")

Answer 3

Have a look at this example:

from tkinter import *

root = Tk()

text = Text(root)
text.insert(INSERT, "Hello, world!\n")
text.insert(END, "This is a phrase.\n")
text.insert(END, "Bye bye...")
text.pack(expand=1, fill=BOTH)

# adding a tag to a part of text specifying the indices
text.tag_add("start", "1.8", "1.13")
text.tag_config("start", background="black", foreground="yellow")

root.mainloop()

Answer 4

I was able to change the color of the text for every match of a regex using the custom tkinter widget Text to get an event similiar to a 'text_changed':

import tkinter as tk

class CustomText(tk.Text):

def __init__(self, *args, **kwargs):
    """A text widget that report on internal widget commands"""
    tk.Text.__init__(self, *args, **kwargs)

    # create a proxy for the underlying widget
    self._orig = self._w + "_orig"
    self.tk.call("rename", self._w, self._orig)
    self.tk.createcommand(self._w, self._proxy)

def _proxy(self, command, *args):
    cmd = (self._orig, command) + args
    result = self.tk.call(cmd)
    if command in ("insert", "delete", "replace"):
        self.event_generate("<<TextModified>>")
    return result

And then, use it like that:

scr = CustomText(w)
scr.tag_configure('red', foreground = 'red')
scr.tag_configure('purple', foreground = '#a820a1')
scr.bind('<<TextModified>>', self.__textchanged__)

def __textchanged__(self, evt):
    for tag in evt.widget.tag_names():
        evt.widget.tag_remove(tag, '1.0', 'end')
    lines = evt.widget.get('1.0', 'end-1c').split('\n')
    for i, line in enumerate(lines):
        self.__applytag__(i, line, 'red', 'while|if', evt,widget) # your tags here
        self.__applytag__(i, line, 'purple', 'True', evt.widget)  # with a regex

@staticmethod
def __applytag__ (line, text, tag, regex, widget):
    indexes = [(m.start(), m.end()) for m in re.finditer(regex, text)]
    for x in indexes:
        widget.tag_add(tag, f'{line+1}.{x[0]}', f'{line+1}.{x[1]}')