scale(n) Tk Built-In Commands scale(n)
____________________________________________________________________________________________________________
NAME
scale - Create and manipulate scale widgets
SYNOPSIS
scale pathName ?options?
STANDARD OPTIONS
-activebackground -foreground -relief
-background -highlightbackground -repeatdelay
-borderwidth -highlightcolor -repeatinterval
-cursor -highlightthickness -takefocus
-font -orient -troughcolor
See the options manual entry for details on the standard options.
WIDGET-SPECIFIC OPTIONS
Command-Line Name:-bigincrement
Database Name: bigIncrement
Database Class: BigIncrement
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-Line Name:-command
Database Name: command
Database Class: Command
Specifies the prefix of a Tcl command to invoke whenever the scale's value is changed via a
widget command. The actual command consists of this option followed by a space and a real
number indicating the new value of the scale.
Command-Line Name:-digits
Database Name: digits
Database Class: Digits
An integer specifying how many significant digits should be retained when converting the value
of the scale to a string. If the number is less than or equal to zero, then the scale picks
the smallest value that guarantees that every possible slider position prints as a different
string.
Command-Line Name:-from
Database Name: from
Database Class: From
A real value corresponding to the left or top end of the scale.
Command-Line Name:-label
Database Name: label
Database Class: Label
A string to display as a label for the scale. For vertical scales the label is displayed just
to the right of the top end of the scale. For horizontal scales the label is displayed just
above the left end of the scale. If the option is specified as an empty string, no label is
displayed.
Command-Line Name:-length
Database Name: length
Database Class: Length
Specifies the desired long dimension of the scale in screen units (i.e. any of the forms
acceptable to Tk_GetPixels). For vertical scales this is the scale's height; for horizontal
scales it is the scale's width.
Command-Line Name:-resolution
Database Name: resolution
Database Class: Resolution
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).
Command-Line Name:-showvalue
Database Name: showValue
Database Class: ShowValue
Specifies a boolean value indicating whether or not the current value of the scale is to be
displayed.
Command-Line Name:-sliderlength
Database Name: sliderLength
Database Class: SliderLength
Specfies the size of the slider, measured in screen units along the slider's long dimension.
The value may be specified in any of the forms acceptable to Tk_GetPixels.
Command-Line Name:-sliderrelief
Database Name: sliderRelief
Database Class: SliderRelief
Specifies the relief to use when drawing the slider, such as raised or sunken.
Command-Line Name:-state
Database Name: state
Database Class: 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 color specified by the activeBackground option.
Command-Line Name:-tickinterval
Database Name: tickInterval
Database Class: TickInterval
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.
Command-Line Name:-to
Database Name: to
Database Class: To
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.
Command-Line Name:-variable
Database Name: variable
Database Class: Variable
Specifies the name of a global variable to link to the scale. Whenever the value of the vari-able variable
able changes, the scale will update to reflect this value. Whenever the scale is manipulated
interactively, the variable will be modified to reflect the scale's new value.
Command-Line Name:-width
Database Name: width
Database Class: Width
Specifies the desired narrow dimension of the trough in screen units (i.e. any of the forms
acceptable to Tk_GetPixels). For vertical scales this is the trough's width; for horizontal
scales this is the trough's height.
____________________________________________________________________________________________________________
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 or in the option
database to configure aspects of the scale such as its colors, 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, but pathName's parent must exist.
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 Tcl command is invoked (using the command option) to notify other interested wid-gets widgets
gets of the change. In addition, the value of the scale can be linked to a Tcl variable (using the
variable option), so that changes in either are reflected in the other.
Three annotations may be displayed in a scale widget: a label appearing at the top right of the wid-get widget
get (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 left of the
current value (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 Tcl 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 behavior 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 describing all of the available options for pathName (see Tk_ConfigureInfo for informa-tion information
tion on the format of this list). If option is specified with no value, then the command
returns a list describing the one named option (this list will be identical to the correspond-ing corresponding
ing sublist of the value returned if no option is specified). 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 val-ues values
ues accepted by the scale command.
pathName coords ?value?
Returns a list whose elements are the x and y coordinates of the point along the centerline 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 corre-sponding corresponding
sponding 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 class bindings for scales that give them the following default behavior.
Where the behavior is different for vertical and horizontal scales, the horizontal behavior is
described in parentheses.
[1] If button 1 is pressed in the trough, the scale's value will be incremented or decremented by
the value of the resolution 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 button 1 is pressed in the trough with the Control key down, the slider moves all the way
to the end of its range, in the direction towards the mouse cursor.
[4] If button 2 is pressed, the scale's value is set to the mouse position. If the mouse is
dragged with button 2 down, the scale's value changes with the drag.
[5] The Up and Left keys move the slider up (left) by the value of the resolution option.
[6] The Down and Right keys move the slider down (right) by the value of the resolution option.
[7] Control-Up and Control-Left move the slider up (left) by the value of the bigIncrement option.
[8] Control-Down and Control-Right move the slider down (right) by the value of the bigIncrement
option.
[9] Home moves the slider to the top (left) end of its range.
[10] End moves the slider to the bottom (right) end of its range.
If the scale is disabled using the state option then none of the above bindings have any effect.
The behavior of scales can be changed by defining new bindings for individual widgets or by redefin-ing redefining
ing the class bindings.
KEYWORDS
scale, slider, trough, widget
Tk 4.1 scale(n)
|