Tkcalendar：将日历下拉列表与 DateEntry 右对齐

Question

默认情况下，日历下拉菜单和 DateEntry 小部件是左对齐的。在一种情况下，日历会超出屏幕，如图所示。我们能否以某种方式将日历下拉菜单与相应的 DateEntry 小部件右对齐。

Answer 1

可以通过重写 DateEntry 的 drop_down() 方法来 right-align 下拉菜单。下拉菜单是一个 Toplevel，它位于屏幕上

self._top_cal.geometry('+%i+%i' % (x, y))

其中 (x, y) 是下拉菜单的 top-left 角。因此，对于 left-aligned 下拉列表

x = self.winfo_rootx()  # the left side of the entry

现在要获得 right-aligned 下拉列表，我们需要将 x 更改为

x = self.winfo_rootx() + self.winfo_width() - self._top_cal.winfo_reqwidth()

即（条目右侧的位置）-（下拉列表的宽度）。

完整代码：

from tkcalendar import DateEntry
import tkinter as tk

class MyDateEntry(DateEntry):
    def __init__(self, master=None, align='left', **kw):
        DateEntry.__init__(self, master, **kw)
        self.align = align

    def drop_down(self):
        """Display or withdraw the drop-down calendar depending on its current state."""
        if self._calendar.winfo_ismapped():
            self._top_cal.withdraw()
        else:
            self._validate_date()
            date = self.parse_date(self.get())
            if self.align == 'left':  # usual DateEntry
                x = self.winfo_rootx()
            else:  # right aligned drop-down
                x = self.winfo_rootx() + self.winfo_width() - self._top_cal.winfo_reqwidth()
            y = self.winfo_rooty() + self.winfo_height()
            if self.winfo_toplevel().attributes('-topmost'):
                self._top_cal.attributes('-topmost', True)
            else:
                self._top_cal.attributes('-topmost', False)
            self._top_cal.geometry('+%i+%i' % (x, y))
            self._top_cal.deiconify()
            self._calendar.focus_set()
            self._calendar.selection_set(date)


root = tk.Tk()

tk.Label(root, text='left align').grid(row=0, column=0)
tk.Label(root, text='right align').grid(row=0, column=1)
MyDateEntry(root).grid(row=1, column=0)
MyDateEntry(root, align='right').grid(row=1, column=1)

root.mainloop()

编辑：您还可以检测drop-down是否会超出屏幕并自动调整drop-down位置以避免：

def drop_down(self):
    """Display or withdraw the drop-down calendar depending on its current state."""
    if self._calendar.winfo_ismapped():
        self._top_cal.withdraw()
    else:
        self._validate_date()
        date = self.parse_date(self.get())
        h = self._top_cal.winfo_reqheight()
        w = self._top_cal.winfo_reqwidth()
        x_max = self.winfo_screenwidth()
        y_max = self.winfo_screenheight()
        # default: left-aligned drop-down below the entry
        x = self.winfo_rootx()
        y = self.winfo_rooty() + self.winfo_height()
        if x + w > x_max:  # the drop-down goes out of the screen
            # right-align the drop-down
            x += self.winfo_width() - w
        if y + h > y_max:  # the drop-down goes out of the screen
            # bottom-align the drop-down
            y -= self.winfo_height() + h
        if self.winfo_toplevel().attributes('-topmost'):
            self._top_cal.attributes('-topmost', True)
        else:
            self._top_cal.attributes('-topmost', False)
        self._top_cal.geometry('+%i+%i' % (x, y))
        self._top_cal.deiconify()
        self._calendar.focus_set()
        self._calendar.selection_set(date)

请注意，由于 tkinter 仅检测到一个大矩形屏幕，因此在使用多个显示器时此解决方案将无法正常工作。

Tkcalendar：将日历下拉列表与 DateEntry 右对齐

Tkcalendar: Right align calendar dropdown with the DateEntry

python

tkinter

tkinter-layout

tkcalendar