python tkinter画布没有调整大小

Question

我正在尝试对一些 tkinter 控件进行子类化以制作用于我的程序的自动滚动框架，我只希望它垂直滚动，并且当添加需要它水平滚动而不是调整父级大小以适应的小部件时.进入该框架的小部件并非全部在运行时定义并且是动态创建的，因此它必须对事件做出反应。我有一些部分工作的代码，因为我运行它，我可以使用底部的按钮即时添加和删除标签，如果我这样做而不先手动调整窗口大小，那么它会按预期工作。但是，如果我手动调整窗口大小，水平调整大小将停止工作：

from tkinter import *

__all__ = ["VerticalScrolledFrame"]

class VerticalScrolledFrame(Frame):
    def __init__(self, parent, *args, **kw):
        Frame.__init__(self, parent, *args, **kw)            
        self.grid_columnconfigure(1, weight=1)
        self.grid_rowconfigure(1, weight=1)
        # create a canvas object and a vertical scrollbar for scrolling it
        self.vscrollbar = Scrollbar(self, orient=VERTICAL)
        self.vscrollbar.grid(column=2, row=1, sticky="nesw")
        self.canvas = Canvas(self, bd=0, highlightthickness=0, yscrollcommand=self.vscrollbar.set, height=10, width=10)
        self.canvas.grid(column=1, row=1, sticky="nesw")
        self.vscrollbar.config(command=self.canvas.yview)

        # reset the view
        self.canvas.xview_moveto(0)
        self.canvas.yview_moveto(0)

        # create a frame inside the canvas which will be scrolled with it
        self.interior = Frame(self.canvas)
        self.interior_id = self.canvas.create_window(0, 0, window=self.interior, anchor=NW)

        self.interior.bind('<Configure>', self._configure_interior)

        # track changes to the canvas and frame width and sync them,
        # also updating the scrollbar
    def _configure_interior(self, event=None):
        print("config interior")
        # update the scrollbars to match the size of the inner frame
        size = (self.interior.winfo_width(), self.interior.winfo_height())
        self.canvas.config(scrollregion="0 0 %s %s" % size)
        if self.interior.winfo_reqwidth() > self.canvas.winfo_width():
            # update the canvas's width to fit the inner frame
            self.canvas.config(width=self.interior.winfo_reqwidth())

if __name__ == "__main__":
    labels = []
    labels2 = []
    def add1():
        l = Label(f.interior, text=str(len(labels)+1))
        l.grid(column=len(labels)+1, row=1)
        labels.append(l)

    def remove1():
        l = labels.pop()
        l.grid_forget()
        l.destroy()

    def add2():
        l = Label(f.interior, text=str(len(labels2)+1))
        l.grid(column=1, row=len(labels2)+1)
        labels2.append(l)

    def remove2():
        l = labels2.pop()
        l.grid_forget()
        l.destroy()

    app = Tk()
    app.grid_columnconfigure(1, weight=1)
    app.grid_columnconfigure(2, weight=1)
    app.grid_rowconfigure(1, weight=1)
    f = VerticalScrolledFrame(app)
    f.grid(column=1, row=1, columnspan=2, sticky="nesw")
    Button(app, text="Add-H", command=add1).grid(column=1, row=2, sticky="nesw")
    Button(app, text="Remove-H", command=remove1).grid(column=2, row=2, sticky="nesw")
    Button(app, text="Add-V", command=add2).grid(column=1, row=3, sticky="nesw")
    Button(app, text="Remove-V", command=remove2).grid(column=2, row=3, sticky="nesw")
    app.mainloop()

我只在 Windows 上工作并使用 python 3.3，我也尝试了 3.4，但没有任何变化。

为什么调整窗口大小会停止调用：

self.canvas.config(width=self.interior.winfo_reqwidth())

下班了吗？

编辑： Brian Oakley 的回答是有道理的，所以我可以理解这种行为，但是我现在已经更改了我的代码，以便在调整窗口大小时也处理对画布大小的更改：

from tkinter import *

__all__ = ["VerticalScrolledFrame"]

class VerticalScrolledFrame(Frame):
    def __init__(self, parent, *args, **kw):
        Frame.__init__(self, parent, *args, **kw)
        p = parent
        while True:
            if p.winfo_class() in ['Tk', 'Toplevel']:
                break
            else:
                p = self._nametowidget(p.winfo_parent())
        self.root_window = p
        self.grid_columnconfigure(1, weight=1)
        self.grid_rowconfigure(1, weight=1)
        # create a canvas object and a vertical scrollbar for scrolling it
        self.vscrollbar = Scrollbar(self, orient=VERTICAL)
        self.vscrollbar.grid(column=2, row=1, sticky="nesw")
        self.canvas = Canvas(self, bd=0, highlightthickness=0, yscrollcommand=self.vscrollbar.set, height=10, width=10)
        self.canvas.grid(column=1, row=1, sticky="nesw")
        self.vscrollbar.config(command=self.canvas.yview)

        # reset the view
        self.canvas.xview_moveto(0)
        self.canvas.yview_moveto(0)

        # create a frame inside the canvas which will be scrolled with it
        self.interior = Frame(self.canvas)
        self.interior_id = self.canvas.create_window(0, 0, window=self.interior, anchor=NW)

        self.interior.bind('<Configure>', self._configure_interior)

        self.canvas.bind('<Configure>', self._configure_canvas)

        # track changes to the canvas and frame width and sync them,
        # also updating the scrollbar
    def _configure_interior(self, event=None):
        print("config interior")
        # update the scrollbars to match the size of the inner frame
        size = (self.interior.winfo_width(), self.interior.winfo_height())
        self.canvas.config(scrollregion="0 0 %s %s" % size)
        if self.interior.winfo_reqwidth() >= self.canvas.winfo_width():
            # update the canvas's width to fit the inner frame
            # only works before mainloop
            self.canvas.config(width=self.interior.winfo_reqwidth())
        screen_h = self.winfo_screenheight()
        if ((self.root_window.winfo_rooty() + self.root_window.winfo_height() - self.canvas.winfo_height() + self.interior.winfo_reqheight()) < screen_h):
            self.canvas.configure(height=self.interior.winfo_reqheight())

    def _configure_canvas(self, event=None):
        print("config canvas")
        if self.interior.winfo_reqwidth() < self.canvas.winfo_width():
            self.canvas.itemconfigure(self.interior_id, width=self.canvas.winfo_width())
        elif self.interior.winfo_reqwidth() > self.canvas.winfo_width():
            self.canvas.config(width=self.interior.winfo_reqwidth())

        if (self.interior.winfo_reqheight() < self.canvas.winfo_height()) or (self.interior.winfo_height() < self.canvas.winfo_height()):
            self.canvas.itemconfigure(self.interior_id, height=self.canvas.winfo_height())

if __name__ == "__main__":
    labels = []
    labels2 = []
    def add1():
##        app.geometry("")
        l = Label(f.interior, text=str(len(labels)+1))
        l.grid(column=len(labels)+1, row=1)
        f.interior.grid_columnconfigure(len(labels)+1, weight=1, minsize=l.winfo_reqwidth())
        labels.append(l)

    def remove1():
##        app.geometry("")
        l = labels.pop()
        l.grid_forget()
        f.interior.grid_columnconfigure(len(labels)+2, weight=0, minsize=0)
        l.destroy()

    def add2():
        l = Label(f.interior, text=str(len(labels2)+1))
        l.grid(column=1, row=len(labels2)+1)
        f.interior.grid_rowconfigure(len(labels2)+1, weight=1, minsize=l.winfo_reqheight())
        labels2.append(l)

    def remove2():
        l = labels2.pop()
        l.grid_forget()
        f.interior.grid_rowconfigure(len(labels2)+2, weight=0, minsize=0)
        l.destroy()

    app = Tk()
    app.grid_columnconfigure(1, weight=1)
    app.grid_columnconfigure(2, weight=1)
    app.grid_rowconfigure(1, weight=1)
    f = VerticalScrolledFrame(app)
    f.grid(column=1, row=1, columnspan=2, sticky="nesw")
    Button(app, text="Add-H", command=add1).grid(column=1, row=2, sticky="nesw")
    Button(app, text="Remove-H", command=remove1).grid(column=2, row=2, sticky="nesw")
    Button(app, text="Add-V", command=add2).grid(column=1, row=3, sticky="nesw")
    Button(app, text="Remove-V", command=remove2).grid(column=2, row=3, sticky="nesw")
    for i in range(0,10):
        add1()
        add2()
    app.mainloop()

我现在看到的问题是，如果我在调整窗口大小之前垂直添加项目，则会为每个添加的小部件调用 _configure_interior 函数，并且窗口会垂直调整大小以适应（如果在调整窗口大小之前）和如果没有，它应该更新滚动区域（和滚动条），但是在调整窗口大小后，_configure_interior 在添加每个小部件时停止被调用，如果我手动调用它，滚动条仍然没有更新？

Answer 1

为什么调整窗口大小会停止调用：

self.canvas.config(width=self.interior.winfo_reqwidth())

那是因为你的代码绑定到 frame 变化。当用户调整窗口大小时，您调整的是 window，而不是 frame。如果您希望在调整窗口大小时调用该函数，除了自动调整内部框架的大小之外，您还必须将其或类似的函数绑定到窗口或画布的大小调整。

您还需要注意，如果用户调整窗口大小，向画布中的框架添加对象不会使窗口变大。用户选择的窗口大小将覆盖正在调整大小的内部小部件的计算大小。您必须将几何图形重置为空字符串才能使其自动增长。