scale - Create and manipulate 'scale' value-controlled slider
widgets
-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.
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 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
- Specifies 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 will not 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. The values will all be
displayed with the same number of decimal places, which will be enough to
ensure they are all accurate to within 20% of a tick interval. 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 variable 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 scale in screen units (i.e.
any of the forms acceptable to Tk_GetPixels). For vertical scales
this is the scale's width; for horizontal scales this is the scale's
height.
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 widgets 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 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
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.
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 information
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 corresponding 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 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 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 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 is
not 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.
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 redefining the class bindings.
scale, slider, trough, widget