将滚动条添加到Tkinter中的一组小部件

Question

我使用Python来解析日志文件中的条目,并使用Tkinter显示条目内容,到目前为止它非常好.输出是标签小部件的网格,但有时会有比屏幕上显示的行多的行.我想添加一个滚动条,看起来应该很容易,但我无法弄明白.

该文档暗示只有List,Textbox,Canvas和Entry小部件支持滚动条界面.这些似乎都不适合显示小部件网格.可以在Canvas小部件中放置任意小部件,但您似乎必须使用绝对坐标,因此我无法使用网格布局管理器？

我已经尝试将小部件网格放入框架,但这似乎不支持滚动条界面,所以这不起作用:

mainframe = Frame(root, yscrollcommand=scrollbar.set)

任何人都可以建议绕过这个限制吗？我不想在PyQt中重写并增加我的可执行图像大小,只需要添加一个滚动条!

Answer 1

概观

您只能将滚动条与几个小部件相关联,并且根小部件Frame不属于该组小部件.

最常见的解决方案是创建画布小部件并将滚动条与该小部件相关联.然后,在该画布中嵌入包含标签小部件的框架.确定框架的宽度/高度并将其输入到画布scrollregion选项中,以使滚动区域与框架的大小完全匹配.

直接在画布上绘制文本项目并不是很难,因此如果框架嵌入画布解决方案看起来过于复杂,您可能需要重新考虑该方法.由于您正在创建网格,因此每个文本项的坐标将非常容易计算,尤其是如果每行的高度相同(如果您使用单个字体,则可能是这样).

要直接在画布上绘图,只需计算出您正在使用的字体的行高(并且有相应的命令).然后,每个y坐标是row*(lineheight+spacing).x坐标将是基于每列中最宽项目的固定数字.如果为其所在的列提供标记,则可以使用单个命令调整列中所有项的x坐标和宽度.

面向对象的解决方案

下面是使用面向对象方法的框架嵌入式画布解决方案的示例:

import tkinter as tk

class Example(tk.Frame):
    def __init__(self, root):

        tk.Frame.__init__(self, root)
        self.canvas = tk.Canvas(root, borderwidth=0, background="#ffffff")
        self.frame = tk.Frame(self.canvas, background="#ffffff")
        self.vsb = tk.Scrollbar(root, orient="vertical", command=self.canvas.yview)
        self.canvas.configure(yscrollcommand=self.vsb.set)

        self.vsb.pack(side="right", fill="y")
        self.canvas.pack(side="left", fill="both", expand=True)
        self.canvas.create_window((4,4), window=self.frame, anchor="nw", 
                                  tags="self.frame")

        self.frame.bind("<Configure>", self.onFrameConfigure)

        self.populate()

    def populate(self):
        '''Put in some fake data'''
        for row in range(100):
            tk.Label(self.frame, text="%s" % row, width=3, borderwidth="1", 
                     relief="solid").grid(row=row, column=0)
            t="this is the second column for row %s" %row
            tk.Label(self.frame, text=t).grid(row=row, column=1)

    def onFrameConfigure(self, event):
        '''Reset the scroll region to encompass the inner frame'''
        self.canvas.configure(scrollregion=self.canvas.bbox("all"))

if __name__ == "__main__":
    root=tk.Tk()
    Example(root).pack(side="top", fill="both", expand=True)
    root.mainloop()

程序解决方案

这是一个不使用对象的解决方案:

import tkinter as tk

def populate(frame):
    '''Put in some fake data'''
    for row in range(100):
        tk.Label(frame, text="%s" % row, width=3, borderwidth="1", 
                 relief="solid").grid(row=row, column=0)
        t="this is the second column for row %s" %row
        tk.Label(frame, text=t).grid(row=row, column=1)

def onFrameConfigure(canvas):
    '''Reset the scroll region to encompass the inner frame'''
    canvas.configure(scrollregion=canvas.bbox("all"))

root = tk.Tk()
canvas = tk.Canvas(root, borderwidth=0, background="#ffffff")
frame = tk.Frame(canvas, background="#ffffff")
vsb = tk.Scrollbar(root, orient="vertical", command=canvas.yview)
canvas.configure(yscrollcommand=vsb.set)

vsb.pack(side="right", fill="y")
canvas.pack(side="left", fill="both", expand=True)
canvas.create_window((4,4), window=frame, anchor="nw")

frame.bind("<Configure>", lambda event, canvas=canvas: onFrameConfigure(canvas))

populate(frame)

root.mainloop()

注意:要在python 2.x中使用Tkinter它,请使用而不是tkinter在import语句中

Answer 2

扩展类tk.Frame以支持可滚动的 Frame
该类独立于要滚动的小部件，可用于替换标准tk.Frame.

import tkinter as tk

class ScrollbarFrame(tk.Frame):
    """
    Extends class tk.Frame to support a scrollable Frame 
    This class is independent from the widgets to be scrolled and 
    can be used to replace a standard tk.Frame
    """
    def __init__(self, parent, **kwargs):
        tk.Frame.__init__(self, parent, **kwargs)

        # The Scrollbar, layout to the right
        vsb = tk.Scrollbar(self, orient="vertical")
        vsb.pack(side="right", fill="y")

        # The Canvas which supports the Scrollbar Interface, layout to the left
        self.canvas = tk.Canvas(self, borderwidth=0, background="#ffffff")
        self.canvas.pack(side="left", fill="both", expand=True)

        # Bind the Scrollbar to the self.canvas Scrollbar Interface
        self.canvas.configure(yscrollcommand=vsb.set)
        vsb.configure(command=self.canvas.yview)

        # The Frame to be scrolled, layout into the canvas
        # All widgets to be scrolled have to use this Frame as parent
        self.scrolled_frame = tk.Frame(self.canvas, background=self.canvas.cget('bg'))
        self.canvas.create_window((4, 4), window=self.scrolled_frame, anchor="nw")

        # Configures the scrollregion of the Canvas dynamically
        self.scrolled_frame.bind("<Configure>", self.on_configure)

    def on_configure(self, event):
        """Set the scroll region to encompass the scrolled frame"""
        self.canvas.configure(scrollregion=self.canvas.bbox("all"))

用法：

class App(tk.Tk):
    def __init__(self):
        super().__init__()

        sbf = ScrollbarFrame(self)
        self.grid_rowconfigure(0, weight=1)
        self.grid_columnconfigure(0, weight=1)
        sbf.grid(row=0, column=0, sticky='nsew')
        # sbf.pack(side="top", fill="both", expand=True)

        # Some data, layout into the sbf.scrolled_frame
        frame = sbf.scrolled_frame
        for row in range(50):
            text = "%s" % row
            tk.Label(frame, text=text,
                     width=3, borderwidth="1", relief="solid") \
                .grid(row=row, column=0)

            text = "this is the second column for row %s" % row
            tk.Label(frame, text=text,
                     background=sbf.scrolled_frame.cget('bg')) \
                .grid(row=row, column=1)


if __name__ == "__main__":
    App().mainloop()

Answer 3

使它滚动

使用这个方便的类使包含小部件的框架可滚动。跟着这些步骤：

1. 创建框架
2. 显示它（包装，网格等）
3. 使它滚动
4. 在其中添加小部件
5. 调用update（）方法

import tkinter as tk
from tkinter import ttk

class Scrollable(tk.Frame):
    """
       Make a frame scrollable with scrollbar on the right.
       After adding or removing widgets to the scrollable frame, 
       call the update() method to refresh the scrollable area.
    """

    def __init__(self, frame, width=16):

        scrollbar = tk.Scrollbar(frame, width=width)
        scrollbar.pack(side=tk.RIGHT, fill=tk.Y, expand=False)

        self.canvas = tk.Canvas(frame, yscrollcommand=scrollbar.set)
        self.canvas.pack(side=tk.LEFT, fill=tk.BOTH, expand=True)

        scrollbar.config(command=self.canvas.yview)

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

        # base class initialization
        tk.Frame.__init__(self, frame)         

        # assign this obj (the inner frame) to the windows item of the canvas
        self.windows_item = self.canvas.create_window(0,0, window=self, anchor=tk.NW)


    def __fill_canvas(self, event):
        "Enlarge the windows item to the canvas width"

        canvas_width = event.width
        self.canvas.itemconfig(self.windows_item, width = canvas_width)        

    def update(self):
        "Update the canvas and the scrollregion"

        self.update_idletasks()
        self.canvas.config(scrollregion=self.canvas.bbox(self.windows_item))

使用范例

root = tk.Tk()

header = ttk.Frame(root)
body = ttk.Frame(root)
footer = ttk.Frame(root)
header.pack()
body.pack()
footer.pack()

ttk.Label(header, text="The header").pack()
ttk.Label(footer, text="The Footer").pack()


scrollable_body = Scrollable(body, width=32)

for i in range(30):
    ttk.Button(scrollable_body, text="I'm a button in the scrollable frame").grid()

scrollable_body.update()

root.mainloop()