tkinter.Button

SYNOPSIS

instance = tkinter.Button(parent ,**options)

STANDARD OPTIONS

activebackground
activeforeground
anchor
background or bg
bitmap
borderwidth or bd
compound
cursor
disabledforeground
font
foreground or fg
highlightbackground
highlightcolor
highlightthickness
image
justify
padx
pady
relief
repeatdelay
repeatinterval
takefocus
text
textvariable
underline
wraplength

WIDGET-SPECIFIC OPTIONS

command
Specifies a Python callback to associate with the button. This callback is typically invoked when mouse button 1 is released over the button window.

default
Specifies one of three states for the default ring: "normal", "active", or "disabled". In "active" state, the button is drawn with the platform specific appearance for a default button. In "normal" state, the button is drawn with the platform specific appearance for a non-default button, leaving enough space to draw the default button appearance. The "normal" and "active" states will result in buttons of the same size. In "disabled" state, the button is drawn with the non-default button appearance without leaving space for the default appearance. The "disabled" state may result in a smaller button than the active state.

height
Specifies a desired height for the button. If an image or bitmap is being displayed in the button then the value is in screen units (i.e. any of the forms acceptable to Screen Units); for text it is in lines of text. If this option is not specified, the button's desired height is computed from the size of the image or bitmap or text being displayed in it.

overrelief
Specifies an alternative relief for the button, to be used when the mouse cursor is over the widget. This option can be used to make toolbar buttons, by configuring relief="flat" overrelief="raised". If the value of this option is the empty string, then no alternative relief is used when the mouse cursor is over the button. The empty string is the default value.

state
Specifies one of three states for the button: "normal", "active", or "disabled". In normal state the button is displayed using the foreground and background options. The "active" state is typically used when the pointer is over the button. In "active" state the button is displayed using the activeforeground and activebackground options. "disabled" state means that the button should be insensitive: the default bindings will refuse to activate the widget and will ignore mouse button presses. In this state the disabledforeground and background options determine how the button is displayed.

width
Specifies a desired width for the button. If an image or bitmap is being displayed in the button then the value is in screen units (i.e. any of the forms acceptable to Screen Units). For a text button (no image or with compound="none") then the width specifies how much space in characters to allocate for the text label. If the width is negative then this specifies a minimum width. If this option is not specified, the button's desired width is computed from the size of the image or bitmap or text being displayed in it.

A button is a widget that displays a textual string, bitmap or image. If text is displayed, it must all be in a single font, but it can occupy multiple lines on the screen (if it contains newlines or if wrapping occurs because of the wraplength option) and one of the characters may optionally be underlined using the underline option. It can display itself in either of three different ways, according to the state option; it can be made to appear raised, sunken, or flat; and it can be made to flash. When a user invokes the button (by pressing mouse button 1 with the cursor over the button), then the Python callback specified in the command option is invoked.

WIDGET COMMAND

The following commands are possible for button widgets:

instance.cget("option")
Returns the current value of the configuration option given by option. Option may have any of the values accepted by the Button class.

instance.configure()
instance.configure("option")
instance.configure(**options)
Query or modify the configuration options of the widget.
If no option is specified, returns a list describing all of the available options for instance: the elements of the list are the option name, database name, database class, default value, and current value.
If "option" is specified, then the method returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified).
If **options are specified, then the command modifies the given widget option(s) to have the given value(s); in this case the method returns an empty string. Option may have any of the values accepted by the Button class.

instance.invoke()
Invoke the Python callback associated with the button, if there is one. The return value is the return value from the Python callback, or an empty string if there is no callback associated with the button. This method is ignored if the button's state is "disabled".

DEFAULT BINDINGS

Tkinter automatically creates class bindings for buttons that give them default behavior:

1.A button activates whenever the mouse passes over it and deactivates whenever the mouse leaves the button. Under Windows, this binding is only active when mouse button 1 has been pressed over the button.

2.A button's relief is changed to sunken whenever mouse button 1 is pressed over the button, and the relief is restored to its original value when button 1 is later released.

3.If mouse button 1 is pressed over a button and later released over the button, the button is invoked. However, if the mouse is not over the button when button 1 is released, then no invocation occurs.

4.When a button has the input focus, the space key causes the button to be invoked.

If the button's state is "disabled" then none of the above actions occur: the button is completely non-responsive.

The behavior of buttons can be changed by defining new bindings for individual widgets or by redefining the class bindings.