[Tkinter-discuss] Navigation in menu with multiple columns

[Vasilis Vlachoudis]

Great, many thanks Michael!
________________________________
From: Michael Lange <klappnase at web.de>
Sent: Sunday 17 September 2023 02:14
To: Vasilis Vlachoudis <Vasilis.Vlachoudis at cern.ch>
Cc: tkinter-discuss at python.org <tkinter-discuss at python.org>
Subject: Re: [Tkinter-discuss] Navigation in menu with multiple columns

Hi Vasilis,

On Fri, 15 Sep 2023 09:55:49 +0000
Vasilis Vlachoudis <Vasilis.Vlachoudis at cern.ch> wrote:

> Hi Michael,
>
> here is a snipped of a code and what I've managed up to now

thanks, I get your point now :-)

I toyed around with your example a bit and came up with a custom menu
class (see below; for testing I added a few useless separators and another
submenu to the demo code). It's far from being perfect, but at least the
keyboard navigation appears to work (It might require more thorough
testing, though. Separators appear to be especially tricky.). Just for the
fun of it I also added keybindings for the PageUp, PageDown, Home and End
keys, which I thought might come in handy when dealing with huge submenus.

Have a nice day,

Michael

################################################################

import tkinter

class GriddedMenu(tkinter.Menu):
    '''Menu with lots of menu items arranged in a grid.'''
    # TODO: insert(), delete(), add_cascade(), add_checkbutton(),
    # add_radiobutton(), add_separator(), configure()
    def __init__(self, parent, numrows=20, **kw):
        tkinter.Menu.__init__(self, parent, **kw)
        self.numrows = numrows
        self._curindex = -1
        if self.type(0) == 'tearoff':
            self._curindex = 0
        self.bind("<Right>", self._on_key_right)
        self.bind("<Left>", self._on_key_left)
        self.bind("<Prior>", self._on_key_pageup)
        self.bind("<Next>", self._on_key_pagedown)
        self.bind("<Home>", self._on_key_home)
        self.bind("<End>", self._on_key_end)

    def add_cascade(self, **kw):
        # FIXME: handle columnbreaks
        tkinter.Menu.add_cascade(self, **kw)
        self._curindex += 1

    def add_command(self, **kw):
        tkinter.Menu.add_command(self, **kw)
        self._curindex += 1
        if (self._curindex >= self.numrows) and \
                                (self._curindex % self.numrows == 0):
            self.entryconfigure(self._curindex, columnbreak=1)

    def add_separator(self, **kw):
        # FIXME: handle columnbreaks
        tkinter.Menu.add_separator(self, **kw)
        self._curindex += 1

    def _on_key_left(self, event):
        index = self.index('active')
        if index - self.numrows >= 0:
            newindex = index - self.numrows
            while (newindex >= 0) and (self.type(newindex) == 'separator'):
                newindex -= self.numrows
            if newindex >= 0:
                self.activate(newindex)
            return 'break'

    def _on_key_right(self, event):
        index = self.index('active')
        end = self.index('end')
        if index + self.numrows <= end:
            newindex = index + self.numrows
            while (newindex <= end) and (self.type(newindex) == 'separator'):
                newindex += self.numrows
            if newindex <= end:
                self.activate(newindex)
            return 'break'

    def _on_key_pageup(self, event):
        index = self.index('active')
        row = index % self.numrows
        newindex = index - row
        while self.type(newindex) == 'separator':
            newindex += 1
        self.activate(newindex)

    def _on_key_pagedown(self, event):
        index = self.index('active')
        row = index % self.numrows
        newindex = min(self.index('end'), index + (self.numrows - row - 1))
        while self.type(newindex) == 'separator':
            newindex -= 1
        self.activate(newindex)

    def _on_key_home(self, event):
        newindex = 0
        while self.type(newindex) == 'separator':
            newindex += 1
        self.activate(newindex)

    def _on_key_end(self, event):
        newindex = self.index('end')
        while self.type(newindex) == 'separator':
            newindex -= 1
        self.activate(newindex)

#------------------------------------------------------------------------------

if __name__ == "__main__":

    def show_menu(event):
        menu = tkinter.Menu(tearoff=0)
        for label in ["one","two","three","four"]:
            submenu = GriddedMenu(menu)
            menu.add_cascade(label=label, menu=submenu)
            for i in range(8):
                submenu.add_command(label=f"Item #{i}")
            submenu.add_separator()
            for i in range(8, 57):
                submenu.add_command(label=f"Item #{i}")
            submenu.add_separator()
            for i in range(57, 72):
                submenu.add_command(label=f"Item #{i}")
            submenu.add_separator()
            for i in range(72, 101):
                submenu.add_command(label=f"Item #{i}")
            submenu.add_separator()
            subsubmenu = tkinter.Menu(submenu)
            submenu.add_cascade(label='foo', menu=subsubmenu)
            subsubmenu.add_command(label='bar')
            submenu.add_separator()
        menu.tk_popup(event.x_root, event.y_root)

    root = tkinter.Tk()
    tkinter.Label(root, text="<1> Left click to show menu").pack()
    tkinter.Label(root, text="<q> to exit").pack()
    root.bind("<1>", show_menu)
    root.bind("<Key-q>", lambda e: root.destroy())
    root.mainloop()

###############################################################################
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