四、tk布局

GUI编程必须有的布局（Layout）

Java Swing、Qt等都有布局管理，tkinter也不例外，且一共有三种类型：

布局	描述
pack	相对布局
grid	网格布局
place	绝对布局

1. pack布局

   默认将先使用的放在上面，然后依次向下排列，它自动给组件一个自认为合适的位置和大小，这是最简单的模式，可以直接使用pack()函数，不需要添加参数，但是不代表没有参数。下面我们来看一下源码：

   class Pack:
       """Geometry manager Pack.
   
       Base class to use the methods pack_* in every widget."""
   
       def pack_configure(self, cnf={}, **kw):
           """Pack a widget in the parent widget. Use as options:
           after=widget - pack it after you have packed widget
           anchor=NSEW (or subset) - position widget according to
                                     given direction
           before=widget - pack it before you will pack widget
           expand=bool - expand widget if parent size grows
           fill=NONE or X or Y or BOTH - fill widget if widget grows
           in=master - use master to contain this widget
           in_=master - see 'in' option description
           ipadx=amount - add internal padding in x direction
           ipady=amount - add internal padding in y direction内边距垂直方向
           padx=amount - add padding in x direction外边距水平方向
           pady=amount - add padding in y direction外边距垂直方向
           side=TOP or BOTTOM or LEFT or RIGHT -  where to add this widget.
           """
           self.tk.call(
                 ('pack', 'configure', self._w)
                 + self._options(cnf, kw))

   可以看到还是有不少的参数的，通过描述可以看到一些它们的功能。

   参数	功能
   after	在其他组件pack之后再pack，理解为降低优先级，可选值为某个widget
   before	pack后再pack其他组件，理解为提高优先级，可选值为某个widget
   in	用哪个父组件包含，可选值为某个widget
   expand	是否随着父组件的尺寸变化而跟着改变位置，可选值为YES或NO
   fill	在某个方向填充，可选值为X或Y或NONE或BOTH
   ipadx	水平方向内边距，可选值为数值
   ipady	垂直方向内边距，可选值为数值
   padx	水平方向外边距，可选值为数值
   pady	垂直方向外边距，可选值为数值
   side	组件的停靠位置或方向，可选值为TOP或BOTTOM或LEFT或RIGHT

2. grid布局

   class Grid:
       """Geometry manager Grid.
   
       Base class to use the methods grid_* in every widget."""
       # Thanks to Masazumi Yoshikawa (yosikawa@isi.edu)
   
       def grid_configure(self, cnf={}, **kw):
           """Position a widget in the parent widget in a grid. Use as options:
           column=number - use cell identified with given column (starting with 0)
           columnspan=number - this widget will span several columns
           in=master - use master to contain this widget
           in_=master - see 'in' option description
           ipadx=amount - add internal padding in x direction
           ipady=amount - add internal padding in y direction
           padx=amount - add padding in x direction
           pady=amount - add padding in y direction
           row=number - use cell identified with given row (starting with 0)
           rowspan=number - this widget will span several rows
           sticky=NSEW - if cell is larger on which sides will this
                         widget stick to the cell boundary
           """
           self.tk.call(
                 ('grid', 'configure', self._w)
                 + self._options(cnf, kw))

3. place布局

   class Place:
       """Geometry manager Place.
   
       Base class to use the methods place_* in every widget."""
   
       def place_configure(self, cnf={}, **kw):
           """Place a widget in the parent widget. Use as options:
           in=master - master relative to which the widget is placed
           in_=master - see 'in' option description
           x=amount - locate anchor of this widget at position x of master
           y=amount - locate anchor of this widget at position y of master
           relx=amount - locate anchor of this widget between 0.0 and 1.0
                         relative to width of master (1.0 is right edge)
           rely=amount - locate anchor of this widget between 0.0 and 1.0
                         relative to height of master (1.0 is bottom edge)
           anchor=NSEW (or subset) - position anchor according to given direction
           width=amount - width of this widget in pixel
           height=amount - height of this widget in pixel
           relwidth=amount - width of this widget between 0.0 and 1.0
                             relative to width of master (1.0 is the same width
                             as the master)
           relheight=amount - height of this widget between 0.0 and 1.0
                              relative to height of master (1.0 is the same
                              height as the master)
           bordermode="inside" or "outside" - whether to take border width of
                                              master widget into account
           """
           self.tk.call(
                 ('place', 'configure', self._w)
                 + self._options(cnf, kw))