NAME¶
Tk::Button - Create and manipulate Button widgets
SYNOPSIS¶
$button =
$parent->
Button(?
options?);
STANDARD OPTIONS¶
-activebackground -activeforeground -anchor
-background -bitmap -borderwidth -compound
-cursor -disabledforeground -font -foreground
-highlightbackground -highlightcolor -highlightthickness
-image -justify -padx -pady -relief
-repeatdelay -repeatinterval -takefocus -text
-textvariable -underline -wraplength
See Tk::options for details of the standard options.
- Name: command
- Class: Command
- Switch: -command
- Specifies a Perl/Tk callback to associate with the button.
This command is typically invoked when mouse button 1 is released over the
button window.
- Command-Line Name: -compound
- Database Name: compound
- Database Class: Compound
- Specifies whether the button should display both an image
and text, and if so, where the image should be placed relative to the
text. Valid values for this option are bottom, center,
left, none, right and top. The default value
is none, meaning that the button will display either an image or
text, depending on the values of the -image and -bitmap options.
- Name: default
- Class: Default
- Switch: -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. ring.
- Name: height
- Class: Height
- Switch: -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 Tk_GetPixels); for text it is
in lines of text. If this option isn't specified, the button's desired
height is computed from the size of the image or bitmap or text being
displayed in it.
- Command-Line Name: -overrelief
- Database Name: overRelief
- Database Class: 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.
- Name: state
- Class: State
- Switch: -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.
- Name: width
- Class: Width
- Switch: -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 Tk_GetPixels); for text it is
in characters. If this option isn't specified, the button's desired width
is computed from the size of the image or bitmap or text being displayed
in it.
DESCRIPTION¶
The
Button method creates a new window (given by the $widget argument)
and makes it into a button widget. Additional options, described above, may be
specified on the command line or in the option database to configure aspects
of the button such as its colors, font, text, and initial relief. The
button command returns its $widget argument. At the time this command
is invoked, there must not exist a window named $widget, but $widget's parent
must exist.
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 perl/Tk callback specified in the
-command option is
invoked.
The
Button method creates a widget object. This object supports the
configure and
cget methods described in Tk::options which can be
used to enquire and modify the options described above. The widget also
inherits all the methods provided by the generic Tk::Widget class.
The following additional methods are available for button widgets:
- $button->flash
- Flash the button. This is accomplished by redisplaying the
button several times, alternating between active and normal colors. At the
end of the flash the button is left in the same normal/active state as
when the command was invoked. This command is ignored if the button's
state is disabled.
- $button->invoke
- Invoke the callback associated with the buttons
-command option, if there is one. The return value is the return
value from the callback, or the undefined value if there is no callback
associated with the button. This command is ignored if the button's state
is disabled.
DEFAULT BINDINGS¶
Tk 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.
KEYWORDS¶
button, widget