I've recently found a code in StackOverflow which inherits the Text class to add -textvariable option to it (as Text widget originally has no -textvariable option) and another code which also inherits the Text class to add a scrollbar to it by default (I found it from source code of Tkinter).
Text with scrollbar:
class ScrolledText(Text):
def __init__(self, master=None, **kwargs):
self.frame = Frame(master)
self.vbar = Scrollbar(self.frame)
self.vbar.pack(side=RIGHT, fill=Y)
kwargs.update({'yscrollcommand': self.vbar.set})
Text.__init__(self, self.frame, **kwargs)
self.pack(side=LEFT, fill=BOTH, expand=True)
self.vbar['command'] = self.yview
text_meths = vars(Text).keys()
methods = vars(Pack).keys() | vars(Grid).keys() | vars(Place).keys()
methods = methods.difference(text_meths)
for m in methods:
if m[0] != '_' and m != 'config' and m != 'configure':
setattr(self, m, getattr(self.frame, m))
def __str__(self):
return str(self.frame)
Text with -textvariable option:
class TextWithVar(Text):
def __init__(self, parent, *args, **kwargs):
try:
self._textvariable = kwargs.pop("textvariable")
except KeyError:
self._textvariable = None
super().__init__(parent, *args, **kwargs)
if self._textvariable is not None:
self.insert("1.0", self._textvariable.get())
self.tk.eval('''
proc widget_proxy {widget widget_command args} {
set result [uplevel [linsert $args 0 $widget_command]]
if {([lindex $args 0] in {insert replace delete})} {
event generate $widget <<Change>> -when tail
}
return $result
}
''')
self.tk.eval('''
rename {widget} _{widget}
interp alias {{}} ::{widget} {{}} widget_proxy {widget} _{widget}
'''.format(widget=str(self)))
self.bind("<<Change>>", self._on_widget_change)
if self._textvariable is not None:
self._textvariable.trace("wu", self._on_var_change)
def _on_var_change(self, *args):
text_current = self.get("1.0", "end-1c")
var_current = self._textvariable.get()
if text_current != var_current:
self.delete("1.0", "end")
self.insert("1.0", var_current)
def _on_widget_change(self, event=None):
if self._textvariable is not None:
self._textvariable.set(self.get("1.0", "end-1c"))
I tried to merge them:
class ScrolledTextWithVar(Text):
def __init__(self, master=None, *args, **kwargs):
try:
self._textvariable = kwargs.pop("textvariable")
except KeyError:
self._textvariable = None
self.frame = Frame(master)
self.vbar = Scrollbar(self.frame)
self.vbar.pack(side=RIGHT, fill=Y)
kwargs.update({'yscrollcommand': self.vbar.set})
super().__init__(self.frame, **kwargs)
self.pack(side=LEFT, fill=BOTH, expand=True)
self.vbar['command'] = self.yview
text_meths = vars(Text).keys()
methods = vars(Pack).keys() | vars(Grid).keys() | vars(Place).keys()
methods = methods.difference(text_meths)
for m in methods:
if m[0] != '_' and m != 'config' and m != 'configure':
setattr(self, m, getattr(self.frame, m))
if self._textvariable is not None:
self.insert("1.0", self._textvariable.get())
self.tk.eval('''
proc widget_proxy {widget widget_command args} {
set result [uplevel [linsert $args 0 $widget_command]]
if {([lindex $args 0] in {insert replace delete})} {
event generate $widget <<Change>> -when tail
}
return $result
}
''')
self.tk.eval('''
rename {widget} _{widget}
interp alias {{}} ::{widget} {{}} widget_proxy {widget} _{widget}
'''.format(widget=str(self)))
self.bind("<<Change>>", self._on_widget_change)
if self._textvariable is not None:
self._textvariable.trace("wu", self._on_var_change)
def _on_var_change(self, *args):
text_current = self.get("1.0", "end-1c")
var_current = self._textvariable.get()
if text_current != var_current:
self.delete("1.0", "end")
self.insert("1.0", var_current)
def _on_widget_change(self, event=None):
if self._textvariable is not None:
self._textvariable.set(self.get("1.0", "end-1c"))
def __str__(self):
return str(self.frame)
Even though the ScrolledTextWithVar class accepts -textvariable as an argument, it does not update the variable value when the text inside the widget changes. Removing the lines which add scrollbar to the widget makes the -textvariable option work again. I have no idea how can scrollbar and textvariable conflict each other. Is adding a scrollbar externally only solution to this?
The problem here is that ScrolledText is overloading the __str__() method and therefore the widget=str(self) in TextWithVar.__init__() does not refer to the right widget, namely the container frame instead of the text widget. You can fix that by using the original text widget method:
widget=str(tk.Text.__str__(self)))
Also, you don't really have to merge the two classes, you can make your class inherit directly from ScrolledText instead of Text:
import tkinter as tk
from tkinter.scrolledtext import ScrolledText
# same code as TextWithVar but inheriting from ScrolledText and with above mentioned fix
class ScrolledTextWithVar(ScrolledText):
def __init__(self, parent, *args, **kwargs):
try:
self._textvariable = kwargs.pop("textvariable")
except KeyError:
self._textvariable = None
super().__init__(parent, *args, **kwargs)
if self._textvariable is not None:
self.insert("1.0", self._textvariable.get())
self.tk.eval('''
proc widget_proxy {widget widget_command args} {
set result [uplevel [linsert $args 0 $widget_command]]
if {([lindex $args 0] in {insert replace delete})} {
event generate $widget <<Change>> -when tail
}
return $result
}
''')
self.tk.eval('''
rename {widget} _{widget}
interp alias {{}} ::{widget} {{}} widget_proxy {widget} _{widget}
'''.format(widget=str(tk.Text.__str__(self)))) # <-- use tk.Text str method
self.bind("<<Change>>", self._on_widget_change)
if self._textvariable is not None:
self._textvariable.trace("wu", self._on_var_change)
def _on_var_change(self, *args):
text_current = self.get("1.0", "end-1c")
var_current = self._textvariable.get()
if text_current != var_current:
self.delete("1.0", "end")
self.insert("1.0", var_current)
def _on_widget_change(self, event=None):
if self._textvariable is not None:
self._textvariable.set(self.get("1.0", "end-1c"))
root = tk.Tk()
var = tk.StringVar(root)
txt = ScrolledTextWithVar(root, textvariable=var)
txt.pack(side="left", fill="both", expand=True)