SCALE(9)SCALE(9)NAMEscale - Create and manipulate scale widgets
SYNOPSISscale pathName ?options?
STANDARD OPTIONS-activebackground -font -orient
-background-foreground-relief
-borderwidth-highlightcolor-takefocus
-disabledcolor-highlightthickness
WIDGET-SPECIFIC OPTIONS
-bigincrement dist
Some interactions with the scale cause its value to change by
``large'' increments; this option specifies the size of the
large increments. If specified as 0, the large increments
default to 1/10 the range of the scale.
-command command
Specifies the prefix of a Tk command to invoke whenever the
scale's value is changed via a widget command. The actual com‐
mand consists of this option followed by a space and a real num‐
ber indicating the new value of the scale.
-from frac
A real value corresponding to the left or top end of the scale.
-height dist
Specifies a desired height for the scale. If this option isn't
specified, the scale is given a default height.
-label string
A string to display as a label for the scale. If the option is
specified as an empty string, no label is displayed.
-resolution frac
A real value specifying the resolution for the scale. If this
value is greater than zero then the scale's value will always be
rounded to an even multiple of this value, as will tick marks
and the endpoints of the scale. If the value is less than zero
then no rounding occurs. Defaults to 1 (i.e., the value will be
integral).
-showvalue boolean
Specifies a boolean value indicating whether or not the current
value of the scale is to be displayed.
-sliderlength dist
Specfies the size of the slider along the slider's long dimen‐
sion..
-sliderrelief relief
Specifies the relief to use when drawing the slider.
-state state
Specifies one of three states for the scale: normal, active, or
disabled. If the scale is disabled then the value may not be
changed and the scale won't activate. If the scale is active,
the slider is displayed using the colour specified by the
activebackground option.
-tickinterval frac
Must be a real value. Determines the spacing between numerical
tick marks displayed below or to the left of the slider. If 0,
no tick marks will be displayed.
-to frac
Specifies a real value corresponding to the right or bottom end
of the scale. This value may be either less than or greater
than the from option.
-width dist
Specifies a desired width for the scale. If this option isn't
specified, the scale is given a default width.
DESCRIPTION
The scale command creates a new window (given by the pathName argument)
and makes it into a scale widget. Additional options, described above,
may be specified on the command line to configure aspects of the scale
such as its colours, orientation, and relief. The scale command
returns its pathName argument. At the time this command is invoked,
there must not exist a window named pathName.
A scale is a widget that displays a rectangular trough and a small
slider. The trough corresponds to a range of real values (determined
by the from, to, and resolution options), and the position of the
slider selects a particular real value. The slider's position (and
hence the scale's value) may be adjusted with the mouse or keyboard as
described in the BINDINGS section below. Whenever the scale's value is
changed, a Tk command is invoked (using the command option) to notify
other interested widgets of the change.
Three annotations may be displayed in a scale widget: a label appear‐
ing at the top right of the widget (top left for horizontal scales), a
number displayed just to the left of the slider (just above the slider
for horizontal scales), and a collection of numerical tick marks just
to the right of the trough (just below the trough for horizontal
scales). Each of these three annotations may be enabled or disabled
using the configuration options.
WIDGET COMMAND
The scale command creates a new Tk command whose name is pathName.
This command may be used to invoke various operations on the widget.
It has the following general form:
pathName option ?arg arg ...?
Option and the args determine the exact behaviour of the command. The
following commands are possible for scale widgets:
pathName cget option
Returns the current value of the configuration option given by
option. Option may have any of the values accepted by the scale
command.
pathName configure ?option? ?value option value ...?
Query or modify the configuration options of the widget. If no
option is specified, returns a list of all of the available
options for pathName. If one or more option-value pairs are
specified, then the command modifies the given widget option(s)
to have the given value(s); in this case the command returns an
empty string. Option may have any of the values accepted by the
scale command.
pathName coords ?value?
Returns a list whose elements are the x and y coordinates of the
point along the centreline of the trough that corresponds to
value. If value is omitted then the scale's current value is
used.
pathName get ?x y?
If x and y are omitted, returns the current value of the scale.
If x and y are specified, they give pixel coordinates within the
widget; the command returns the scale value corresponding to
the given pixel. Only one of x or y is used: for horizontal
scales y is ignored, and for vertical scales x is ignored.
pathName identify x y
Returns a string indicating what part of the scale lies under
the coordinates given by x and y. A return value of slider
means that the point is over the slider; trough1 means that the
point is over the portion of the slider above or to the left of
the slider; and trough2 means that the point is over the portion
of the slider below or to the right of the slider. If the point
isn't over one of these elements, an empty string is returned.
pathName set value
This command is invoked to change the current value of the
scale, and hence the position at which the slider is displayed.
Value gives the new value for the scale. The command has no
effect if the scale is disabled.
BINDINGS
Tk automatically creates bindings for scales that give them the follow‐
ing default behaviour. Where the behaviour is different for vertical
and horizontal scales, the horizontal behaviour is described in paren‐
theses.
[1] If button 1 is pressed in the trough, the scale's value will be
incremented or decremented by the value of the bigincrement
option so that the slider moves in the direction of the cursor.
If the button is held down, the action auto-repeats.
[2] If button 1 is pressed over the slider, the slider can be
dragged with the mouse.
[3] If the widget receives Up-arrow or Left-arrow key events, the
scale's value will be incremented or decremented so as to adjust
the value towards the fromvalue.
[4] If the widget receives Down-arrow or Right-arrow key events, the
scale's value will be incremented or decremented so as to adjust
the value towards the tovalue.
If the scale is disabled using the state option then none of the above
bindings have any effect.
The behaviour of scales can be changed by defining new bindings for
individual widgets.
SEE ALSOoptions(9), types(9)SCALE(9)