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.so man.macros

.TH scale n 4.1 Tk "Tk Built-In Commands"

.BS

'\" Note:  do not modify the .SH NAME line immediately below!

.SH NAME

scale \- Create and manipulate scale widgets

.SH SYNOPSIS

\fBscale\fR \fIpathName \fR?\fIoptions\fR?

.SO

\-activebackground      \-font  \-highlightthickness    \-repeatinterval

\-background    \-foreground    \-orient        \-takefocus

\-borderwidth   \-highlightbackground   \-relief        \-troughcolor

\-cursor        \-highlightcolor        \-repeatdelay

.SE

.SH "WIDGET-SPECIFIC OPTIONS"

.OP \-bigincrement bigIncrement 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.

.OP \-command command 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.

.OP \-digits digits 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.

.OP \-from from From

A real value corresponding to the left or top end of the scale.

.OP \-label label 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.

.OP \-length length Length

Specifies the desired long dimension of the scale in screen units

(i.e. any of the forms acceptable to \fBTk_GetPixels\fR).

For vertical scales this is the scale's height;  for horizontal scales

it is the scale's width.

.OP \-resolution resolution 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).

.OP \-showvalue showValue ShowValue

Specifies a boolean value indicating whether or not the current

value of the scale is to be displayed.

.OP \-sliderlength sliderLength 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 \fBTk_GetPixels\fR.

.OP \-sliderrelief sliderRelief SliderRelief

Specifies the relief to use when drawing the slider, such as \fBraised\fR

or \fBsunken\fR.

.OP \-state state State

Specifies one of three states for the scale:  \fBnormal\fR,

\fBactive\fR, or \fBdisabled\fR.

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 \fBactiveBackground\fR option.

.OP \-tickinterval tickInterval 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.

.OP \-to to 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 \fBfrom\fR option.

.OP \-variable variable 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.

.OP \-width width Width

Specifies the desired narrow dimension of the trough in screen units

(i.e. any of the forms acceptable to \fBTk_GetPixels\fR).

For vertical scales this is the trough's width;  for horizontal scales

this is the trough's height.

.BE

.SH DESCRIPTION

.PP

The \fBscale\fR command creates a new window (given by the

\fIpathName\fR 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 \fBscale\fR command returns its

\fIpathName\fR argument.  At the time this command is invoked,

there must not exist a window named \fIpathName\fR, but

\fIpathName\fR's parent must exist.

.PP

A scale is a widget that displays a rectangular \fItrough\fR and a

small \fIslider\fR.  The trough corresponds to a range

of real values (determined by the \fBfrom\fR, \fBto\fR, and

\fBresolution\fR 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 \fBcommand\fR 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 \fBvariable\fR

option), so that changes in either are reflected in the other.

.PP

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.

.SH "WIDGET COMMAND"

.PP

The \fBscale\fR command creates a new Tcl command whose

name is \fIpathName\fR.  This

command may be used to invoke various

operations on the widget.  It has the following general form:

.CS

\fIpathName option \fR?\fIarg arg ...\fR?

.CE

\fIOption\fR and the \fIarg\fRs

determine the exact behavior of the command.  The following

commands are possible for scale widgets:

.TP

\fIpathName \fBcget\fR \fIoption\fR

Returns the current value of the configuration option given

by \fIoption\fR.

\fIOption\fR may have any of the values accepted by the \fBscale\fR

command.

.TP

\fIpathName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR?

Query or modify the configuration options of the widget.

If no \fIoption\fR is specified, returns a list describing all of

the available options for \fIpathName\fR (see \fBTk_ConfigureInfo\fR for

information on the format of this list).  If \fIoption\fR is specified

with no \fIvalue\fR, 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 \fIoption\fR is specified).  If

one or more \fIoption\-value\fR 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.

\fIOption\fR may have any of the values accepted by the \fBscale\fR

command.

.TP

\fIpathName \fBcoords \fR?\fIvalue\fR?

Returns a list whose elements are the x and y coordinates of

the point along the centerline of the trough that corresponds

to \fIvalue\fR.

If \fIvalue\fR is omitted then the scale's current value is used.

.TP

\fIpathName \fBget\fR ?\fIx y\fR?

If \fIx\fR and \fIy\fR are omitted, returns the current value

of the scale.  If \fIx\fR and \fIy\fR are specified, they give

pixel coordinates within the widget;  the command returns

the scale value corresponding to the given pixel.

Only one of \fIx\fR or \fIy\fR is used:  for horizontal scales

\fIy\fR is ignored, and for vertical scales \fIx\fR is ignored.

.TP

\fIpathName \fBidentify\fR \fIx y\fR

Returns a string indicating what part of the scale lies under

the coordinates given by \fIx\fR and \fIy\fR.

A return value of \fBslider\fR means that the point is over

the slider;  \fBtrough1\fR means that the point is over the

portion of the slider above  or to the left of the slider;

and \fBtrough2\fR 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.

.TP

\fIpathName \fBset\fR \fIvalue\fR

This command is invoked to change the current value of the scale,

and hence the position at which the slider is displayed.  \fIValue\fR

gives the new value for the scale.

The command has no effect if the scale is disabled.

.SH BINDINGS

.PP

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.

.IP [1]

If button 1 is pressed in the trough, the scale's value will

be incremented or decremented by the value of the \fBresolution\fR

option so that the slider moves in the direction of the cursor.

If the button is held down, the action auto-repeats.

.IP [2]

If button 1 is pressed over the slider, the slider can be dragged

with the mouse.

.IP [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.

.IP [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.

.IP [5]

The Up and Left keys move the slider up (left) by the value

of the \fBresolution\fR option.

.IP [6]

The Down and Right keys move the slider down (right) by the value

of the \fBresolution\fR option.

.IP [7]

Control-Up and Control-Left move the slider up (left) by the

value of the \fBbigIncrement\fR option.

.IP [8]

Control-Down and Control-Right move the slider down (right) by the

value of the \fBbigIncrement\fR option.

.IP [9]

Home moves the slider to the top (left) end of its range.

.IP [10]

End moves the slider to the bottom (right) end of its range.

.PP

If the scale is disabled using the \fBstate\fR option then

none of the above bindings have any effect.

.PP

The behavior of scales can be changed by defining new bindings for

individual widgets or by redefining the class bindings.

.SH KEYWORDS

scale, slider, trough, widget