Question

I’m working on an application to edit DNA sequences and I’d like to have a tkinter text widget in which only letters atgcATGC can be entered.

Is there any easy way to do that?

Thanks,
David

Answer 1

I finally found a way to have the exact behavior I want:

from Tkinter import Text, BOTH
import re

class T(Text):

    def __init__(self, *a, **b):

        # Create self as a Text.
        Text.__init__(self, *a, **b)

        #self.bind("<Button-1>", self.click)
        self.bind("<Key>", self.key)
        self.bind("<Control-v>", self.paste)

    def key(self,k):
        if k.char and k.char not in "atgcATGC":
            return "break"

    def paste(self,event):
        clip=self.selection_get(selection='CLIPBOARD')
        clip=clip.replace("\n","").replace("\r","")
        m=re.match("[atgcATGC]*",clip)
        if m and m.group()==clip:
            self.clipboard_clear()
            self.clipboard_append(clip)
        else:
            self.clipboard_clear()
            return


t = T()
t.pack(expand=1, fill=BOTH)
t.mainloop()