python tkinter Canvas 不调整大小

Question

我正在尝试对一些 tkinter 控件进行子类化，以制作一个自动滚动框架以在我的程序中使用，我只希望它垂直滚动，并且当添加需要它水平滚动的小部件时，而不是调整父级的大小以适应。此框架中的小部件并非全部在运行时定义，而是动态创建的，因此它必须对事件使用react。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动态添加和删除标签，如果我在不先手动调整窗口大小的情况下执行此操作，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，我也尝试过 3.4，但没有变化。

为什么调整窗口大小会停止调用:

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

上类？

编辑:Brian Oakley 的回应是有道理的，因此我可以理解这种行为，但是我现在更改了代码，以便在调整窗口大小时也处理 Canvas 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，则会为添加的每个小部件调用 _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)，如果没有，则应该更新滚动区域(和滚动条)，但是在调整窗口大小后，添加每个小部件时将停止调用 _configure_interior ，如果我手动调用它，则滚动条还没更新吗？

Answer 1

why does resizing the window stop the call to:

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

那是因为您的代码绑定(bind)到框架更改。当用户调整窗口大小时，您调整的是窗口的大小，而不是框架的大小。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，还必须将其或类似的函数绑定(bind)到窗口或 Canvas 的大小调整。

您还需要注意，如果用户调整窗口大小，向 Canvas 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根据正在调整大小的内部小部件计算的大小。您必须将几何图形重置为空字符串才能使其自动增长。